It has
long been believed that information technology (IT) has the potential to shift
the boundaries surrounding where production takes place. Specifically,
networked IT INVESTMENTS are supposed to reduce costs of monitoring behavior of
internal and external partners, thereby improving incentives and reducing the
risk of opportunistic behavior. Networked IT can also reduce costs of
coordinating economic activity within and between firms.
Tuesday, 9 June 2015
Signaling to Partially Informed Investors in the Newsvendor Model
Companies
face pressure from external investors that leads them to make suboptimal
operations decisions. This pressure arises from three forces: a strong prior
belief that firms are of a "low" type (one with a low quality
INVESTMENT opportunity), an inability for firms to mitigate the information
asymmetry regarding their actual type, and an emphasis on short-term valuation.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
How IT Shapes Top-Down and Bottom-Up Decision Making
Enterprise
Resource Planning software is a decentralizing technology: It provides information
that enables lower-level managers to make more decisions without consulting
their superiors.
By
the same token, Computer-Assisted Design and Computer-Assisted Manufacturing
software creates a situation in which the plant worker needs less access to
superiors in order to make a decision.
The Determinants of Individual Performance and Collective Value in Private-Collective Software Innovation
Knowledge
creation and reuse are important dual goals of social systems organized to
collectively solve technical problems.
Collective
value relies on the ability of others to understand and comprehend the design
structure of knowledge to enable reuse. Thus deviations from commonly
understood rules of practice, while beneficial to the individual innovator,
impede adoption by others.
The Architecture of Complex Systems: Do Core-periphery Structures Dominate
Core-periphery structures dominate the sample, with 75-80 percent of
systems in the sample possessing such a structure.
It
is significant that a substantial number of systems lack such a structure. This
implies that a considerable amount of managerial discretion exists when
choosing the "best" architecture for a system.
Competing Ad Auctions
Participation
costs exist and matter, affecting bidders' decisions about which ad platforms
to use, and changing the welfare consequences of mergers or joins among
platforms.
By
creating a joined ad platform of larger size than Microsoft or Yahoo alone, the
transaction lets advertisers spread participation costs over a larger purchase,
making it worthwhile for small to midsize advertisers to sign up with the
joined Microsoft-Yahoo platform even though they do not use Microsoft or Yahoo
separately.
Gray Markets and Multinational Transfer Pricing
A
shift to arm's-length transfer pricing erodes domestic consumer surplus by
making the gray MARKET less competitive domestically.
In
the presence of a gray market, the transfer price that maximizes a
multinational's profits may also be the same one that maximizes the social
welfare of the domestic economy that houses it.
Optimal Deterrence when Judgment-Proof Agents Are Paid In Arrears—With an Application to Online Advertising Fraud
Online
advertising MARKETS are one of many MARKETS where agents may be effectively
unreachable through the legal system.
Online
advertising contracts presently lack any institution by which the payment
structure can enforce good practices.
Scale without Mass: Business Process Replication and Industry Dynamics
Since
the mid-1990s, IT-intensive industries have seen higher levels of turbulence
and concentration growth than have non-IT-intensive industries.
The
improved ability of firms to replicate business innovations affects not only
productivity, but also the nature of business competition itself.
The Business of Free Software: Enterprise Incentives, Investment, and Motivation in the Open Source Community
Cluster
1, the "money-driven cluster," consisted of projects that have
received almost all of vendor INVESTMENTS. The eighteen projects in this
cluster have received over $2 billion in INVESTMENT.
Cluster
2, the "community-driven cluster," has a large number of projects
that have received almost no vendor INVESTMENT. IT vendors have generally
ignored projects in this cluster and appear to have no coordinated strategy for
dealing with them.
Online Match-Making with Virtual Dates
Technology
influences the tone and trajectory of relationships.
The interface of online dating sites should be improved to help people
filter better.
Virtual Dates is an experimental interface that allows couples to
communicate in real time using colors, words, and images.
The
idea of virtual spaces for natural interactions may have applications for
managers and entrepreneurs.
Monday, 8 June 2015
Treating cutaneous aging with patented technologies
Cutaneous
aging is a multifactorial process affecting different constituents of the skin
(Reddy and Gilchrest 2011). During aging, distribution of subcutaneous fat is
altered. The subcutaneous fat is significantly lost from the dorsum of the
hand, face and shin, but accumulates in the waist or thigh (Kligman et al.1985;
Farage et al.2007). In the epidermis, signs of aging include lowering of the
levels of collagen IV and collagen VII at the basement membrane, flattening of
the rete ridge, thinning of the epidermis, and lowering of the levels of
ceramides, free fatty acids, squalene and epidermal cholesterol (El-Domyati et
al.2002; Hayashi et al.2003; Sandby-Moller et al.2003; Neerken et al.2004; Fore
2006). In the dermis, aging leads to fragmentation of elastin, an increase in
collagen degradation, and a decrease in production of dermal collagen,
proteoglycans and glycosaminoglycans.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Early postnatal exposure to lithium in vitro induces changes in AMPAR mEPSCs and vesicular recycling at hippocampal glutamatergic synapses
Lithium
is an effective mood stabilizer but its use is associated with many side
effects. Electrophysiological recordings of miniature excitatory postsynaptic
currents (mEPSCs) mediated by glutamate receptor AMPA-subtype (AMPARs) in
hippocampal pyramidal neurons revealed that CLi (therapeutic concentration of 1
mM lithium, from days in vitro 4-10) decreased the mean amplitude and mean
rectification index (RI) of AMPAR mEPSCs. Lowered mean RI indicate that
contribution of Ca2+-permeable AMPARs in synaptic events is higher in CLi
neurons (supported by experiments sensitive to Ca2+-permeable AMPAR
modulation). Co-inhibiting PKA, GSK-3β and glutamate reuptake was necessary to
bring about changes in AMPAR mEPSCs similar to that seen in CLi neurons. FM1-43
experiments revealed that recycling pool size was affected in CLi cultures.
Social and cultural issues in genetic counseling
Medical
genetics has rapidly emerged as a definitive branch of modern medicine with an
increasing number of illnesses described as having an aetiological basis in
alterations in one or more genes. Communication of the nature and implications
of these disorders to the ‘at risk’ family is the basis of genetic counselling.
The complexity of information to be given to a family necessitates a trained
genetic counsellor. This article is based on the author’s experience in
counselling families with genetic disorders, public perceptions and
misconceptions, and the influence of local customs and traditions on attitudes
towards such disorders .
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Effects of nitric oxide modulating activities on development of enteric nervous system mediated gut motility in chick embryo model
The
enteric nervous system (ENS) arises from the enteric neural crest-derived cells
(ENCCs), and many molecules and biochemical processes may be involved in its
development. This study examined the effects of modulating embryonic nitric
oxide (NO) activity on the intestinal motility induced by ENS.
One-hundred-and-twenty fertilized chicken eggs were assigned to three main
groups and incubated at 37 degrees Centigrade and 60 percent humidity.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Prooxidative effects of aspartame on antioxidant defense status in erythrocytes of rats
When
compared with the control group, the group administrated with ASP indicated
higher values of serum glucose, cholesterol and triglycerides. Significantly
increased concentrations of superoxide anion (O2 .-), hydrogen peroxide (H2O2),
peroxynitrite (ONOO-) and lipid peroxides (LPO) were recorded in the erythrocytes
of ASP treated group in comparison to the control group. In the course of
chronic ASP administration, the following was observed: the concentration of
reduced glutathione (GSH) and the activity of catalase (CAT) increased. Thus,
these findings suggest that long-term consumption of ASP leads to hyperglycemia
and hyperlipidemia, as well as to oxidative stress in erythrocytes.
Variation in ion leakage parameters of two wheat genotypes with different Rht-B1 alleles in response to drought
The
reaction to soil drying was evaluated in two Triticum aestivum near-isogenic
lines carrying different alleles of the height-reducing gene Rht-B1 based on an
improved method for assessment of electrolyte leakage. The two lines were
previously shown to differ in their physiological responses to induced water
deficit stress. Drought was imposed for 6 days on 10-day-old seedlings. Ion
efflux from leaves was measured conductometrically in multiple time points
during the 24 h incubation period, and the obtained biphasic kinetics was
interpreted according to a previously developed theoretical model proposing
different leakage rates through the apoplast and the symplast. Most of the
model parameters were able to properly differentiate the two closely related
genotypes.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Identification and in silico analysis of helical lipid binding regions in proteins belonging to the amphitropic protein family
The
role of protein-lipid interactions is increasingly recognized to be of
importance in numerous biological processes. Bioinformatics is being
increasingly used as a helpful tool in studying protein-lipid interactions.
Especially recently developed approaches recognizing lipid binding regions in
proteins can be implemented. In this study one of those bioinformatics
approaches specialized in identifying lipid binding helical regions in proteins
is expanded. The approach is explored further by features which can be easily
obtained manually.
Websites: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Websites: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Functional genomics of tomato: Opportunities and challenges in post-genome NGS era
The
Tomato Genome Sequencing Project represented a landmark venture in the history
of sequencing projects where both Sanger's and next-generation sequencing (NGS)
technologies were employed, and a highly accurate and one of the best assembled
plant genomes along with a draft of the wild relative, Solanum
pimpinellifolium, were released in 2012. However, the functional potential of
the major portion of this newly generated resource is still undefined. The very
first challenge before scientists working on tomato functional biology is to
exploit this high-quality reference sequence for tapping of the wealth of
genetic variants for improving agronomic traits in cultivated tomatoes. The
sequence data generated recently by 150 Tomato Genome Consortium would further
uncover the natural alleles present in different tomato genotypes.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Insights into brain development and disease from neurogenetic analyses in Drosophila melanogaster
Groundbreaking
work by Obaid Siddiqi has contributed to the powerful genetic toolkit that is
now available for studying the nervous system of Drosophila. Studies carried
out in this powerful neurogenetic model system during the last decade now
provide insight into the molecular mechanisms that operate in neural stem cells
during normal brain development and during abnormal brain tumorigenesis. These
studies also provide strong support for the notion that conserved molecular
genetic programs act in brain development and disease in insects and mammals
including humans.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Molecular determinants of odorant receptor function in insects
The
olfactory system of Drosophila melanogaster provides a powerful model to study
molecular and cellular mechanisms underlying function of a sensory system. In
the 1970s Siddiqi and colleagues pioneered the application of genetics to
olfactory research and isolated several mutant Drosophila with odorant-specific
defects in olfactory behaviour, suggesting that odorants are detected
differentially by the olfactory system. Since then basic principles of
olfactory system function and development have emerged using Drosophila as a
model. Nearly four decades later we can add computational methods to further
our understanding of how specific odorants are detected by receptors.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Wednesday, 3 June 2015
Analysis of humpback whale sounds in shallow waters of the Southeastern Arabian Sea: An indication of breeding habitat
The primary objective of this work was to
present the acoustical identification of humpback whales, detected by using an
autonomous ambient noise measurement system, deployed in the shallow waters of
the Southeastern Arabian Sea (SEAS) during the period January to May 2011.
Seven types of sounds were detected. These were characteristically upsweeps and
downsweeps along with harmonics. Sounds produced repeatedly in a specific
pattern were referred to as phrases (PQRS and ABC). Repeated phrases in a
particular pattern were referred to as themes, and from the spectrographic
analysis, two themes (I and II) were identified. The variation in the acoustic
characteristics such as fundamental frequency, range, duration of the sound
unit, and the structure of the phrases and themes are discussed. Sound units
were recorded from mid-January to mid-March, with a peak in February, when the
mean SST is ~28°C, and no presence was recorded after mid-March. The temporal
and thematic structures strongly determine the functions of the humpback whale
song form. Given the use of song in the SEAS, this area is possibly used as an
active breeding habitat by humpback whales during the winter season.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Evolutionary change and phylogenetic relationships in light of horizontal gene transfer
Horizontal gene transfer has, over the past 25
years, become a part of evolutionary thinking. In the present paper I discuss
horizontal gene transfer (HGT) in relation to contingency, natural selection,
evolutionary change speed and the Tree-of-Life endeavour, with the aim of
contributing to the understanding of the role of HGT in evolutionary processes.
In addition, the challenges that HGT imposes on the current view of evolution
are emphasized.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Frost hardiness of tree species is independent of phenology and macroclimatic niche
The differences in timing in bud burst between
species have been interpreted as an adaptation to late frost events in spring.
Thus, it has been suggested that the degree of frost susceptibility of leaves
is species-specific and depends on the species' phenology and geographic
distribution range. To test for relationships between frost tolerance and
phenology as well as between frost tolerance and distribution range across
Central European tree species, we studied the frost hardiness of closed buds
before bud burst and of freshly opened buds at the time of bud burst. We
hypothesized that species with early bud burst and species distributed in
eastern and northern areas were more frost tolerant than species with late bud
burst and species distributed in western and southern areas. Frost hardiness
was estimated by exposing twigs to 11 frost temperatures between -4 degrees
Centigrade and -80 degrees Centigrade and by assessing tissue damage by the
electrolyte leakage method. In contrast to our hypotheses, neither frost
hardiness of closed buds nor frost hardiness of freshly opened buds were
related to any variable describing species' macroclimatic niche. Furthermore,
frost hardiness of freshly opened buds did not differ among species. Thus, the
investigated species with early bud burst take higher risks of frost damage
than the species with late bud bursts. These findings indicate that frost
hardiness might not play the key role in limiting the geographic distribution
ranges previously anticipated.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Collagen I-induced dendritic cells activation is regulated by TNF-α production through down-regulation of IRF4
Previously we have shown that collagen I
enhances the maturation and function of dendritic cells (DCs). Inflammatory
mediators such as tumour necrosis factor (TNF)- alpha, interleukin (IL)-1 beta
and lipopolysaccharide (LPS) are also known to activate DCs. Here we
investigated the involvement of TNF-alpha on the collagen I-induced DCs
activation. TNF-a neutralization inhibited collagen I-induced IL-12 secretions
by DCs. Additionally, we observed suppression of collagen I-induced
costimulatory molecules expression along with down-regulation of genes involved
in DCs activation pathway. Furthermore, TNF- alpha inhibition upon collagen
Istimulation up-regulated the expression of interferon regulatory transcription
factor IRF4, when COMPARED to collagen I only treated cells. Collectively, our
data demonstrate that collagen I induce TNF- alpha production, which is crucial
for the activation and function of DCs, through down-regulation of IRF4, and
implicates the importance in development of anti- TNF-alpha therapeutics for
several inflammatory diseases.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Stochastic developmental variation, an epigenetic source of phenotypic diversity with far-reaching biological consequences
This article reviews the production of different
phenotypes from the same genotype in the same environment by stochastic
cellular events, nonlinear mechanisms during patterning and morphogenesis, and
probabilistic self-reinforcing circuitries in the adult life. These aspects of
phenotypic variation are summarized under the term 'stochastic developmental
variation' (SDV) in the following. In the past, SDV has been viewed primarily
as a nuisance, impairing laboratory experiments, pharmaceutical testing, and
true-to-type breeding.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
BARF1 gene silencing triggers caspase-dependent mitochondrial apoptosis in Epstein-Barr virus-positive malignant cells
Epstein-Barr virus (EBV)-encoded BARF1 (BamH1-A
Rightward Frame-1) is expressed in EBV-positive malignancies such as
nasopharyngeal carcinoma, EBV-associated gastric cancer, B-cell lymphoma and
nasal NK/T-cell lymphoma, and has been shown to have an important role in
oncogenesis. However, the mechanism by which BARF1 elicits its biological
effects is unclear. We investigated the effects of BARF1 silencing on cell
proliferation and apoptosis in EBV-positive malignant cells. We observed that
BARF1 silencing significantly inhibits cell proliferation and induces
apoptosis-mediated cell death by collapsing the mitochondrial membrane
potential in AG876 and Hone-Akata cells. BARF1 knockdown up-regulates the
expression of pro-apoptotic proteins and downregulates the expression of
anti-apoptotic proteins.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Biochemical characterization of blood plasma of coronary artery disease patients by in vitro high-resolution proton NMR spectroscopy
This study aimed to investigate the biochemical
profile of blood plasma of patients with coronary artery disease (CAD) and
angiographically normal subjects (controls) to determine biomarkers for their
differentiation. In this double blind study, 5 mL venous blood was drawn before
angiography from CAD patients (n=60) and controls (n=13) comprising angiography
normal individuals. In vitro high-resolution NMR spectroscopy of these blood plasma
samples was carried out at 400 MHz, and intensity data were analysed with
partial least square discriminant analysis. Categorization of subjects as
controls or CAD patients and the patients further as single vessel disease
(SVD), double vessel disease (DVD) and triple vessel disease (TVD) was done at
the end of the study based on their angiography reports. Raised levels of
lipids, alanine (Ala) and isoleucine/leucine/valine (Ile/Leu/Val) were observed
in CAD patients COMPARED with controls. Partial least square discriminant
analysis showed separation between controls vs CAD patients. TVD patients
showed increased levels of Ile/Leu/Val and Ala compared with controls and SVD.
Alanine, Ile/Leu/Val, and LDL/VLDL appear as possible biomarkers for distinguishing
between controls and patients with SVD and TVD. A metabolic adaptation of
myocardium may play a role in raising the Ala level.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Lack of IL-6 increases blood–brain barrier permeability in fungal meningitis
The pathogenesis of increased blood-brain
barrier permeability during Cryptococcus meningitis is still largely unknown.
Interleukin (IL-6) is a multifunctional cytokine, and numerous studies have
shown that IL-6 influences the integrity of the blood-brain barrier. In this
study we investigated the role of IL-6 in Cryptococcus meningitis. First,
wild-type or IL-6-/- mice were injected with Cryptococcus neoformans (C.
neoformans) and the survival time in both groups was recorded. Second, the
number of fungi was measured in the brains of IL-6-/- wild-type mice. Finally,
the blood-brain barrier permeability index was detected in infected IL-6-/-
mice treated with recombinant human IL-6. The blood-brain barrier permeability
index was measured in infected wild-type mice treated with anti-IL-6 antibodies
as well. The survival of IL-6-/- mice injected with C. neoformans was
significantly lower than that of identically challenged wild-type mice. The
infected IL-6-/- mice had significantly larger brain fungal burdens than
wild-type mice. Furthermore, increased blood-brain barrier index was found in
infected IL-6-/- mice when COMPARED with that in infected control mice. Similar
results were obtained when mice challenged with C. neoformans were treated
systemically with neutralizing anti-IL-6 antibodies, resulting in an elevation
of vascular permeability. Our data revealed that IL-6 reduced the blood-brain
barrier permeability during Cryptococcus meningitis, and it might provide an
explanation for the significantly lower survival of infected IL-6-/- mice.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Anti-tumour immune effect of oral administration of Lactobacillus plantarum to CT26 tumour-bearing mice
Colorectal cancer
(CRC) is one of the most prevalent forms of cancer that shows a high mortality
and increasing incidence. There are numerous successful treatment options for
CRC, including surgery, chemotherapy, radiotherapy and immunotherapy; however,
their side effects and limitations are considerable. Probiotics may be an
effective strategy for preventing and inhibiting tumour growth through
stimulation of host innate and adaptive immunity. We investigated and COMPARED
potential anti-tumour immune responses induced by two isolated Lactobacillus
strains, Lactobacillus plantarum A and Lactobacillus rhamnosus b, by
pre-inoculating mice with lactobacilli for 14 days. Subsequently, subcutaneous
and orthotopic intestinal tumours were generated in the pre-inoculated mice
using CT26 murine adenocarcinoma cells and were assessed for response against
the tumour. Our results indicated that oral administration with L. plantarum inhibited
CT26 cell growth in BALB/c mice and prolonged the survival time of
tumour-bearing mice compared with mice administered L. rhamnosus. L. plantarum
produced protective immunity against the challenge with CT26 cells by
increasing the effector functions of CD8+ and natural killer (NK) cell
infiltration into tumour tissue, up-regulation of IFN-γ (but not IL-4 or IL-17)
production, and promotion of Th1-type CD4+ T differentiation. Consequently, our
results suggest that L. plantarum can enhance the anti-tumour immune response
and delay tumour formation
Anti-tumour immune
effect of oral administration of Lactobacillus plantarum to CT26 tumour-bearing
mice.
Effects of nitric oxide modulating activities on development of enteric nervous system mediated gut motility in chick embryo model
The enteric nervous system (ENS) arises from the
enteric neural crest-derived cells (ENCCs), and many molecules and biochemical
processes may be involved in its development. This study examined the effects
of modulating embryonic nitric oxide (NO) activity on the intestinal motility
induced by ENS. One-hundred-and-twenty fertilized chicken eggs were assigned to
three main groups and incubated at 37 degrees Centigrade and 60 percent
humidity. The eggs were treated with NG-nitro-Larginine methyl ester (L-NAME),
sodium nitroprusside (SNP), L-arginine (L-Arg) or vehicle from days 3 (1st
group), 7 (2nd group) and 10 (3rd group) of incubation and continued up to day
18. On day 19, the embryos were sacrificed, the jejunal and colorectal segments
were taken and the intestinal motility was assessed using isolated organ
system.
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Website: http://www.arjonline.org/biosciences/american-research-journal-of-biosciences/
Sunday, 31 May 2015
Quantum cryptography: Public key distribution and coin tossing
When elementary quantum systems, such as polarized photons,
are used to transmit digital information, the uncertainty principle gives rise
to novel cryptographic phenomena unachievable with traditional transmission
media, e.g. a communications channel on which it is impossible in principle to
eavesdrop without a high probability of disturbing the transmission in such a
way as to be detected. Such a quantum channel can be used in conjunction with ordinary
insecure classical channels to distribute random key information between two
users with the assurance that it remains unknown to anyone else, even when the
users share no secret information initially. We also present a protocol for
coin-tossing by exchange of quantum messages, which is secure against
traditional kinds of cheating, even by an opponent with unlimited computing
power, but ironically can be subverted by use of a still subtler quantum
phenomenon, the Einstein–Podolsky–Rosen paradox.
Ant colony optimization theory: A survey
Research on a new metaheuristic for optimization is often
initially focused on proof-of-concept applications. It is only after
experimental work has shown the practical interest of the method that
researchers try to deepen their understanding of the method's functioning not
only through more and more sophisticated experiments but also by means of an
effort to build a theory. Tackling questions such as “how and why the method
works’’ is important, because finding an answer may help in improving its
applicability. Ant colony optimization, which was introduced in the early 1990s
as a novel technique for solving hard combinatorial optimization problems,
finds itself currently at this point of its life cycle. With this article we
provide a survey on theoretical results on ant colony optimization. First, we
review some convergence results. Then we discuss relations between ant colony
optimization algorithms and other approximate methods for optimization.
Finally, we focus on some research efforts directed at gaining a deeper
understanding of the behavior of ant colony optimization algorithms. Throughout
the paper we identify some open questions with a certain interest of being
solved in the near future.
Some simplified NP-complete graph problems
It is widely believed that showing a problem to be
NP-complete is tantamount to proving its computational intractability. In this
paper we show that a number of NP-complete problems remain NP-complete even
when their domains are substantially restricted. First we show the completeness
of Simple Max Cut (Max Cut with edge weights restricted to value 1), and, as a
corollary, the completeness of the Optimal Linear Arrangement problem. We then
show that even if the domains of the Node Cover and Directed Hamiltonian Path
problems are restricted to planar graphs, the two problems remain NP-complete,
and that these and other graph problems remain NP-complete even when their
domains are restricted to graphs with low node degrees. For Graph 3-Colorability,
Node Cover, and Undirected Hamiltonian Circuit, we determine essentially the
lowest possible upper bounds on node degree for which the problems remain
NP-complete.
Bigraphs with sharing
Bigraphical
Reactive Systems (BRS) were designed by Milner as a universal formalism for
modelling systems that evolve in time, locality, co-locality and connectivity.
But the underlying model of location (the place graph) is a forest, which means
there is no straightforward representation of locations that can overlap or intersect.
This occurs in many domains, for example in wireless signalling, social
interactions and audio communications. Here, we define bigraphs with sharing,
which solves this problem by an extension of the basic formalism: we define the
place graph as a directed acyclic graph, thus allowing a natural representation
of overlapping or intersecting locations.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Design and analysis of different alternating variable searches for search-based software testing
Manual
software testing is a notoriously expensive part of the software development
process, and its automation is of high concern. One aspect of the testing
process is the automatic generation of test inputs. This paper studies the
Alternating Variable Method (AVM) approach to search-based test input generation.
The AVM has been shown to be an effective and efficient means of generating
branch-covering inputs for procedural programs. However, there has been little
work that has sought to analyse the technique and further improve its
performance. This paper proposes two different local searches that may be used
in conjunction with the AVM, Geometric and Lattice Search. A theoretical
runtime analysis proves that under certain conditions, the use of these
searches results in better performance compared to the original AVM. These
theoretical results are confirmed by an empirical study with five programs,
which shows that increases of speed of over 50% are possible in practice.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
A framework for co-optimization algorithm performance and its application to worst-case optimization
Traditional
black-box optimization searches a set of potential solutions for those
optimizing the value of a function whose analytical or algebraic form is
unknown or inexistent, but whose value can be queried for any input.
Co-optimization is a generalization of this setting, in which fully evaluating
a potential solution may require querying some function more than once,
typically a very large number of times. When that's the case, co-optimization
poses unique difficulties to designing and assessing algorithms. A
generally-applicable approach is to judge co-optimization algorithm performance
via an aggregate over all possible functions in the problem domain.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Unveiling metamorphism by abstract interpretation of code properties
Metamorphic
code includes self-modifying semantics-preserving transformations to exploit
code diversification. The impact of metamorphism is growing in security and
code protection technologies, both for preventing malicious host attacks, e.g.,
in software diversification for IP and integrity protection, and in malicious
software attacks, e.g., in metamorphic malware self-modifying their own code in
order to foil detection systems based on signature matching. In this paper we
consider the problem of automatically extracting metamorphic signatures from
metamorphic code. We introduce a semantics for self-modifying code, later
called phase semantics, and prove its correctness by showing that it is an
abstract interpretation of the standard trace semantics. Phase semantics
precisely models the metamorphic code behavior by providing a set of traces of
programs which correspond to the possible evolutions of the metamorphic code
during execution. We show that metamorphic signatures can be automatically
extracted by abstract interpretation of the phase semantics. In particular, we
introduce the notion of regular metamorphism, where the invariants of the phase
semantics can be modeled as finite state automata representing the code
structure of all possible metamorphic change of a metamorphic code, and we
provide a static signature extraction algorithm for metamorphic code where
metamorphic signatures are approximated in regular metamorphism.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Fast distributed PageRank computation
Over the last decade, PageRank has gained importance in a
wide range of applications and domains, ever since it first proved to be
effective in determining node importance in large graphs (and was a pioneering
idea behind Google's search engine). In distributed computing alone, PageRank
vector, or more generally random walk based quantities have been used for
several different applications ranging from determining important nodes, load
balancing, search, and identifying connectivity structures. Surprisingly,
however, there has been little work towards designing provably efficient
fully-distributed algorithms for computing PageRank. The difficulty is that
traditional matrix–vector multiplication style iterative methods may not always
adapt well to the distributed setting owing to communication bandwidth
restrictions and convergence rates.
On the variable common due date, minimal tardy jobs bicriteria two-machine flow shop problem with ordered machines
We
consider a special case of the ordinary NP-hard two-machine flow shop problem
with the objective of determining simultaneously a minimal common due date and
the minimal number of tardy jobs. In Panwalkar and Koulamas (2012) [5], the
authors presented quadratic algorithm for the problem when each job has its
smaller processing time on the first machine. In this note, we improve the
running time of the algorithm to O(nlogn)
by efficient implementation using recently introduced modified binary tree data
structure.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
A fixed point theorem for non-monotonic functions
We present a fixed point theorem for a class of
(potentially) non-monotonic functions over specially structured complete
lattices. The theorem has as a special case the Knaster–Tarski fixed point
theorem when restricted to the case of monotonic functions and Kleene's theorem
when the functions are additionally continuous. From the practical side, the
theorem has direct applications in the semantics of negation in logic
programming. In particular, it leads to a more direct and elegant proof of the
least fixed point result of. Moreover, the theorem appears to have potential
for possible applications outside the logic programming domain.
website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Integrated production and delivery scheduling on a serial batch machine to minimize the makespan
In this paper, we study the integrated
production and delivery scheduling on a serial batch machine. The objective is
to minimize the makespan, i.e., the maximum delivery completion time of the
jobs. We consider four distinct problems which depend on whether split is
allowed in the production or delivery of the jobs. We present a polynomial-time
algorithm for the first problem and show that other three problems are strongly
NP-hard. Furthermore, we provide effective approximation algorithms for the three
NP-hard problems.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
The black paper of quantum cryptography: Real implementation problems
The laws of physics play a crucial role in the
security of quantum key distribution (QKD). This fact has often been
misunderstood as if the security of QKD would be based only on the laws of
physics. As the experts know well, things are more subtle. We review the
progresses in practical QKD focusing on (I) the elements of trust that are
common to classical and quantum implementations of key distribution; and (II)
some threats to security that have been highlighted recently, none of which is
unredeemable (i.e., in principle QKD can be made secure). This leads us to
guess that the field, similar to non-quantum modern cryptography, is going to
split in two directions: those who pursue practical devices may have to
moderate their security claims; those who pursue ultimate security may have to
suspend their claims of usefulness.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Global and local sequence alignment with a bounded number of gaps
Pairwise sequence alignment techniques
have gained renewed interest in recent years, primarily due to their
applications in re-sequencing—the assembly of a genome directed by a reference
sequence.
In this article, we show that adding the
flexibility of bounding the number of gaps inserted in an alignment strengthens
the classical sequence alignment scheme of scoring matrices and affine gap
penalty scores. We present GapsMis, an algorithm for pairwise global sequence
alignment with a variable, but bounded, number of gaps. It is based on
computing a variant of the traditional dynamic programming matrix for global
sequence alignment. We also present GapsMis-L, the analogous algorithm for
pairwise local sequence alignment with a variable, but bounded, number of gaps.
A derivative for complex Lipschitz maps with generalized Cauchy–Riemann equations
We introduce the Lipschitz derivative or the
L-derivative of a locally Lipschitz complex map: it is a Scott continuous,
compact and convex set-valued map that extends the classical derivative to the
bigger class of locally Lipschitz maps and allows an extension of the
fundamental theorem of calculus and a new generalisation of Cauchy–Riemann
equations to these maps, which form a continuous Scott domain. We show that a
complex Lipschitz map is analytic in an open set if and only if its
L-derivative is a singleton at all points in the open set. The calculus of the
L-derivative for sum, product and composition of maps is derived. The notion of
contour integration is extended to Scott continuous, non-empty compact, convex
valued functions on the complex plane, and by using the L-derivative, the
fundamental theorem of contour integration is extended to these functions.
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Website: http://www.arjonline.org/engineering/american-research-journal-of-computer-science-and-information-technology/
Friday, 29 May 2015
Effects of Building Configuration on Seismic Performance of RC Buildings by Pushover Analysis
In the recent earthquakes,
concrete structures have been severely damaged or collapsed, which has raised
questions against the seismic adequacy of existing buildings. These existing
reinforced concrete buildings need to be evaluated to determine the capacity to
resist seismic loads. The behavior of a building during earthquakes depends
critically on its overall shape, size and geometry. Conventional approach to
earthquake resistant design of buildings depends upon providing the building
with strength, stiffness and inelastic deformation capacity which are great
enough to withstand a given level of earthquake-generated force. This is
generally accomplished through the selection of an appropriate building
configuration and the careful detailing of structural members. In this
research, nonlinear pushover analysis has been used to evaluate the seismic
performance of three buildings with three different plans having same area and
height. This method determines the base shear capacity of the building and
performance level of each part of building under varying intensity of seismic
force. The results of effects of different plan on seismic response of
buildings have been presented in terms of displacement, base shear and plastic
hinge pattern.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Evaluation of Water Distribution Jointed Pipe Networks under Transient Ground Motions
In this study, a new method
is proposed to evaluate the seismic behavior of buried jointed water pipeline
networks subjected to wave propagation. First, using finite element method and
solid elements, different kinds of currently used connections in the network
are modeled, and their nonlinear behavior in all directions is obtained.
Second, a 950-meter long network consisting of ductile iron pipes segments of
6-meter length and springs characterizing the connections, are modeled using
beam elements. Three-component displacement record of the Tabas earthquake is
applied to the network considering the time lag between support inputs, and the
nonlinear soil-pipe interaction. The record is applied once in North-South
direction and once in East-West direction with different wave propagation
velocities. Results of interest such as stress values and rotations at various
points of the network are then obtained, and critical points are introduced in
each direction. Results show that the points other than the critical ones at
the network intersections remain elastic.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Applications and Prospects of Fiber Reinforced Concrete in Industrial Floors
Upon the view of this work,
industrial floor is a vital structure due to its relation to quality of
production, labor comfort, and human health. Flooring costs may reach 20% of
single-story building construction expenditure, and the consumption of concrete
for floors may come to 40% - 50% of the total size of concrete. Thereby, the
efficient design of floor will reduce materials consumption and labor, and will
increase the endurance of the floor. Fiber reinforcement reduces the thickness
of the subfloor about 20% - 30%, hence enabling to reduce the consumption of
cement and fillers. The use of fiber meshes will enable to save 30% - 40% of
steel. Despite the flexible use of fiber in concrete reinforcement saves effort
and money, still fiber reinforced concrete is lacking additional regulations in
Jordan.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Studies on Strength and Related Properties of Concrete Incorporating Aggregates from Demolished Wastes: Part 2—Compressive and Flexural Strength
In an earlier study, a
comprehensive and critical review of previous investigations into the
assessment of the strength of concrete incorporating aggregates from demolished
wastes was conducted and it was concluded that there was a stark absence of
results from the South African sub-continent including Botswana. In the present
study, recycled coarse aggregates (RCA) sourced from demolished wastes
collected from a landfill site in Gaborone, Botswana was used in lieu of
natural coarse aggregates for the manufacture of concrete. With reference to
the natural coarse aggregate, RCA replacement levels of 0%, 20%, 40%, 60%, 80%
and 100% were utilized and the results of hardened concrete tests for
compressive and flexural strengths were obtained. It was found that in general
the compressive and flexural strengths of the recycled aggregate concrete (RAC)
decreased with increasing replacement levels of natural coarse aggregates using
RCA. It was concluded that RCA could be employed as a substitute for natural
aggregate in concrete only up to a certain limit or partial replacement. In
this respect, it was also noted that the undesirable properties of RCA were
primarily due to the quantity and quality of the adhering mortar.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Seismic Capacity Assessment of Existing RC Buildings in The Sudan by Using Pushover Analysis
Recently, the evaluation of
seismic performance of existing buildings has received a great attention.
Current research works and observations indicate that The Sudan have
low-to-moderate seismic regions. Most of existing buildings are designed only
for gravity load. The objective of this paper is to assess the seismic
performance of existing RC buildings in The Sudan. Four typical buildings were
investigated using pushover analysis according to ATC-40. They were designed
according to the Regulations for earthquake-resistant design of buildings in
Egypt (ESEE) and International Building Code (IBC2012). Results showed that the
buildings designed considering by ESEE and IBC2012 loads were found adequate
and satisfied the Immediate Occupancy (IO) acceptance criteria according to
ATC-40. The comparison of the pushover curve shows that the stiffness of frames
is larger when using ESEE Regulations compared to the IBC2012 design. This
means that ESEE design procedure provides a greater capability to resist
seismic load than the IBC2012 design.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Analysis of Control Measures for Settlement of Differences on the Problems of Highway Subgrade Widening
The study mainly discusses
the issues of the settlement of differences that occurs in the process of
highway subgrade widening. Firstly, it briefly introduces the settlement of
difference and its harms; then it analyzes the mechanism of settlement of
differences in the process of difference widening, including four aspects: the
new and old roadbeds themselves, design, construction and other links; finally,
based on the above analysis of the mechanism, it discusses the corresponding
control measures, mainly proposing these suggestions as followings: the use of
lightweight materials, the foundation treatment, the cut slope excavation
steps, and the strict control of the degree of compaction, etc. The paper is
expected to provide some theoretical basis for the control measures of highway
subgrade widening settlement of difference.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
A Study on Water Repellent Effectiveness of Natural Oil-Applied Soil as a Building Material
This study was performed to
investigate the water repellent effectiveness of natural oil-applied soil when
it is used as a building material. Natural oil types such as olive oil, bean
oil, perilla oil and linseed oil, which are being used for producing water
repellent timber, are selected for the experiments. It is expected that perilla
oil and in seed oil, which are drying oil types will have better water
repellent effectiveness than the other types. For the evaluation of water
repellence of natural oil-applied soil, a contact angle test was performed. A
contact angle of water drop on various surface conditions were tested, and
large differences were seen between the natural oil-applied soil and untreated
soil. As a result, it is showed that all natural oil types have water repellent
effectiveness. However, linseed oil, which is a drying oil type, shows an
outstanding water repellent effectiveness value, while perila oil, which is
also a drying oil type, shows the lowest value. Additionally, results show that
there is no link between water repellent effectiveness and the number of
applications of natural oil. Nevertheless, existing commercial water repellents
show better performance than natural oil, and it is anticipated that the
results of this study will provide essential information for further research
to enhance the water repellent effectiveness of soil as a building material.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
The Effect of Incorporation of Ferrite Nano-particles on Compressive Strength and Re-sistivity of Self-Compacting Concrete
Mn-Ferrite nanoparticles
were prepared using citrate auto combustion method. The prepared sample was
characterized by X-ray diffraction (XRD), HRTEM and BET to measure the particle
diameter and the surface area of the prepared sample. The data of XRD clarified
that the sample was formed in single phase spinel structure without any extra
peaks indicating non-existence of any secondary phase. The HRTEM micrograph
indicated that the particles were in an agglomerated state due to the absence
of surfactant and high magnetic properties of Mn-Ferrite nanoparticles. The
mechanical properties were measured at different ratios of nano-Ferrite to
concrete. The obtained values of mercury intrusion porosimetry (MIP) indicated
that the addition of Mn-Ferrite nanoparticles increased the compressive
strength and decreased the total intrusion volume. This was due to the rapid
consuming of Ca(OH)2 which was formed during hydration of Portland cement
especially at early ages due to the high reactivity of MnFe2O4 nanoparticles.
Moreover, MnFe2O4 nanoparticles recovered the particle packing density of the
blended cement, leading to a reduced volume of pores in the cement paste.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Parametric Study for Replacement of Sand by Fly Ash for Better Packing and Internal Curing
The use of fly ash as
replacement of sand is an economical solution for making green and denser
concrete. The paper presents a concrete mix design procedure for partial
replacement of sand with fly ash. Present method could produce additional
compressive and flexural strength for concrete with partial replacement of sand
with fly ash over control concrete, with higher slump. Addition of 0.5% super
plasticizer could further improve compressive and flexural strength with higher
slump over control concrete. Concrete with sand replaced by fly ash was also
found to be economical without and with super plasticizer, when cost per N/mm2
was compared. The beneficial effect may be attributed to better packing,
pozzolanic activity of fly ash and internal curing by fly ash as partial
replacement of sand. Based on experimental results, correlations are developed
to predict compressive strength, flexural strength and cost per N/mm2 for
percentage sand replacement with fly ash.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Influence Analysis of a New Building to the Bridge Pile Foundation Construction
This paper is based on the
analysis of an industrial factory building to the bridge pile foundation
construction stability, and it researches the influence of a new building to
the bridge pile foundation internal force by the finite element analysis
software ANSYS. By calculating the changes of displacement and internal force
of the bridge pile foundation, the deformation can be better controlled.
Furthermore, comparing the data of numerical analysis with one of monitor
measurements, we conclude that a new building has a small influence on the
deformation under load action and the stress variation of a bridge pile
foundation. That is to say, the bridge pile foundation is safe and stable under
load action.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Subscribe to:
Comments (Atom)