bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomechanical Evaluation of an Anatomically Correct All-Ceramic Tooth-Crown System Configuration: Core Layer Multivariate Analysis Incorporating Clinically Relevant Variables
Authors: Rafferty Brian T. , Bonfante Estevam A. , Janal Malvin N. , Silva Nelson R. F. A. , Rekow Elizabeth D. , Thompson Van P. , Coelho Paulo G.
Published: May 2010

In a crown system, core fracture requires replacement of the restoration. Understanding maximum principal stress concentration in the veneered core of a tooth-crown system as a function of variations in clinically relevant parameters is crucial in the rational design of crown systems. This study evaluated the main and interacting effects of a set of clinical variables on the maximum principal stress (MPS) in the core of an anatomically correct veneer-core-cement-tooth model. A 3D CAD model of a mandibular first molar crown was generated; tooth preparation was modeled by reducing the proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. A cemented veneered core crown was modeled on the preparation. This “crown system” permitted finite element model investigation of the main and interacting effects of proximal wall height reduction, core material, core thickness, cement modulus, cement thickness, and load position on the maximum stress distribution in a factorial design. Analysis of variance was used to identify the main and interacting influences on the level of MPS in the crown core. Statistical significance was set at p<0.05. MPS levels varied as a function of two-way interactions between the following: core thickness and load position; cement thickness and load position; cement modulus and load position; cement thickness and core thickness; and cement thickness and cement modulus; and also three-way interactions among the load position, core material, and proximal wall height reduction, and among the core thickness, cement thickness, and cement modulus. MPS in the crown-tooth system is influenced by the design parameters and also by the interaction among them. Hence, while the geometry of molar crowns is complex, these analyses identify the factors that influence MPS and suggest levels that will minimize the core MPS in future studies of crown design.
Flow and Particle Dispersion in a Pulmonary Alveolus—Part I: Velocity Measurements and Convective Particle Transport
Authors: Chhabra Sudhaker , Prasad Ajay K.
Published: May 2010

The alveoli are the smallest units of the lung that participate in gas exchange. Although gas transport is governed primarily by diffusion due to the small length scales associated with the acinar region (∼500 μm), the transport and deposition of inhaled aerosol particles are influenced by convective airflow patterns. Therefore, understanding alveolar fluid flow and mixing is a necessary first step toward predicting aerosol transport and deposition in the human acinar region. In this study, flow patterns and particle transport have been measured using a simplified in-vitro alveolar model consisting of a single alveolus located on a bronchiole. The model comprises a transparent elastic 5/6 spherical cap (representing the alveolus) mounted over a circular hole on the side of a rigid circular tube (representing the bronchiole). The alveolus is capable of expanding and contracting in phase with the oscillatory flow through the tube. Realistic breathing conditions were achieved by exercising the model at physiologically relevant Reynolds and Womersley numbers. Particle image velocimetry was used to measure the resulting flow patterns in the alveolus. Data were acquired for five cases obtained as combinations of the alveolar-wall motion (nondeforming/oscillating) and the bronchiole flow (none/steady/oscillating). Detailed vector maps at discrete points within a given cycle revealed flow patterns, and transport and mixing of bronchiole fluid into the alveolar cavity. The time-dependent velocity vector fields were integrated over multiple cycles to estimate particle transport into the alveolar cavity and deposition on the alveolar wall. The key outcome of the study is that alveolar-wall motion enhances mixing between the bronchiole and the alveolar fluid. Particle transport and deposition into the alveolar cavity are maximized when the alveolar wall oscillates in tandem with the bronchiole fluid, which is the operating case in the human lung.
Advantages and Drawbacks of Proximal Interphalangeal Joint Fusion Versus Flexor Tendon Transfer in the Correction of Hammer and Claw Toe Deformity. A Finite-Element Study
Authors: Bayod Javier , Losa-Iglesias Marta , Becerro de Bengoa-Vallejo Ricardo , Prados-Frutos Juan Carlos , Jules Kevin T. , Doblaré Manuel
Published: May 2010

Correction of claw or hammer toe deformity can be achieved using various techniques, including proximal interphalangeal joint arthrodesis (PIPJA), flexor digitorum longus tendon transfer (FDLT), and flexor digitorum brevis transfer. PIPJA is the oldest technique, but is associated with significant complications (infection, fracture, delayed union, and nonunion). FDLT eliminates the deformity, but leads to loss of stability during gait. Flexor digitorum brevis tendon transfer (FDBT) seems to be the best surgical alternative, but it is a recent technique with still limited results. In this work, these three techniques have been analyzed by means of the finite-element method and a comparative analysis was done with the aim of extracting advantages and drawbacks. The results show that the best technique for reducing dorsal displacement of the proximal phalanx is PIPJA (2.28 mm versus 2.73 mm for FDLT, and 3.31 mm for FDBT). However, the best technique for reducing stresses on phalanges is FDLT or FDBT (a reduction of approximately 35% regarding the pathologic case versus the increase of 7% for the PIPJA in tensile stresses, and a reduction of approximately 40% versus 25% for the PIPJA in compression stresses). Moreover, the distribution of stresses in the entire phalanx is different for the PIPJA case. These facts could cause problems for patients, in particular, those with pain in the surgical toe.
Sensitivity of Digital Thermal Monitoring Parameters to Reactive Hyperemia
Authors: Akhtar Mohammad W. , Kleis Stanley J. , Metcalfe Ralph W. , Naghavi Morteza
Published: May 2010

Both structural and functional evaluations of the endothelium exist in order to diagnose cardiovascular disease (CVD) in its asymptomatic stages. Vascular reactivity, a functional evaluation of the endothelium in response to factors such as occlusion, cold, and stress, in addition to plasma markers, is the most widely accepted test and has been found to be a better predictor of the health of the endothelium than structural assessment tools such as coronary calcium scores or carotid intima-media thickness. Among the vascular reactivity assessment techniques available, digital thermal monitoring (DTM) is a noninvasive technique that measures the recovery of fingertip temperature after 2–5 min of brachial occlusion. On release of occlusion, the finger temperature responds to the amount of blood flow rate overshoot referred to as reactive hyperemia (RH), which has been shown to correlate with vascular health. Recent clinical trials have confirmed the potential importance of DTM as an early stage predictor of CVD. Numerical simulations of a finger were carried out to establish the relationship between DTM and RH. The model finger consisted of essential components including bone, tissue, major blood vessels (macrovasculature), skin, and microvasculature. The macrovasculature was represented by a pair of arteries and veins, while the microvasculature was represented by a porous medium. The time-dependent Navier–Stokes and energy equations were numerically solved to describe the temperature distribution in and around the finger. The blood flow waveform postocclusion, an input to the numerical model, was modeled as an instantaneous overshoot in flow rate (RH) followed by an exponential decay back to baseline flow rate. Simulation results were similar to clinically measured fingertip temperature profiles in terms of basic shape, temperature variations, and time delays at time scales associated with both heat conduction and blood perfusion. The DTM parameters currently in clinical use were evaluated and their sensitivity to RH was established. Among the parameters presented, temperature rebound (TR) was shown to have the best correlation with the level of RH with good sensitivity for the range of flow rates studied. It was shown that both TR and the equilibrium start temperature (representing the baseline flow rate) are necessary to identify the amount of RH and, thus, to establish criteria for predicting the state of specific patient’s cardiovascular health.
A Method of Generating a Pitch-Up Trajectory Based on a Virtual Target Guidance Law
Authors: Fu Yu , Cui Naigang
Published: May 2010

The pitch-up trajectory is a high parabolic trajectory. Long range interceptor missiles will be important for future air defense. Research indicates that a high parabolic trajectory can enhance the missile range. A method of generating high parabolic trajectories based on a virtual target guidance law is proposed in this paper. The proposed method is formulated and its effectiveness is demonstrated by two test simulations. The simulation results show that a missile can fly in a high parabolic trajectory with good characteristics using the virtual target guidance law. The proposed method fulfills the current needs and is suited for engineering applications.
Explosive Sensitivity Influence on One- and Two-Layered Reactive Armors’ Behavior
Authors: Wiśniewski Adam
Published: May 2010

The use of different explosive reactive armor reactive cassettes is shown. Functioning rules of one- and two-layered reactive cassettes are presented. The paper demonstrates different kinds of tests with explosive reactive armour Wisniewski Adam (ERAWA) cassettes. There are some examples of the simulation of impact of different types armour piercing (AP) and high explosive anti-tank (HEAT) ammunition on these cassettes. Simulation was based on “free points” computer codes. The propagation of the detonative wave in the explosive (PBX 9404 and RDX) has been described with the use of the approximation of the so-called “detonative optics,” in which the front of the detonative wave is a surface of the strong discontinuity of the well-known shape (for the punctual initiation—the front is spherical) of the propagation speed, and the parameters of the medium on this surface are defined by the Chapman–Jouguet’s point. Scattering of products of detonation and their influence on the liner of the RPG-7M projectile are described with the use of equations of the hydrodynamics for the cylindrical symmetry. The results of the simulation process of the impact of AP ammunition of 7.62 mm, 12.7 mm, 14.5 mm, and 125 mm caliber, the type of armour piercing fin stabilized discarting sabot (APFSDS), are illustrated in figures. The changing of the following parameters on the axis, i.e., density, thickness, collapsing velocity, and pressure while penetrating of cassettes in time function, is presented. The next step to test the sensitivity of different types of explosive reactive cassettes containing different explosive layers placed on target, is the observation of their reaction to the impact of kinetic energy ammunition. Explosives contain different percentages of wax. The examples of reaction of the two-layered explosive of different thickness with different contents of wax after projectile impact are illustrated. Computer analysis of the parameters’ changes on the axis of the projectile’s penetration into explosive reactive cassettes, i.e., of density, thickness, pressure, impact velocity for different thicknesses of layers of these cassettes, and the projectile type and velocity 800 m/s and 1800 m/s, enables to know the initiation conditions of these cassettes’ explosive. The use of computer simulation makes possible to know the influence of the quantity of wax on the sensitivity of different thicknesses of explosives of one- and two-layered reactive cassettes.
Vulnerability of Mortar Projectiles by Intercepting Fragmentation Warheads
Authors: Graswald Markus , Brown Ronald E. , Sinibaldi Jose O. , Nolte Timo , Rothe Hendrik
Published: May 2010

A general methodology for estimating the requirements for defeating an explosive-containing mortar threat by an intercepting array of explosively generated natural and controlled fragments is discussed along with the experimental data supporting quantitative interpretation. The target response of covered TNT impacted by single fragments is predicted through numerically determined shock-to-detonation thresholds as well as empirical penetration equations. Included in the methodology is a comprehensive, deterministic endgame model that consists of an intercept model, a static and dynamic fragment model, and a hit model generating the number of effective hits for arbitrary intercept situations. Experimental data supporting the assumptions of the models are reported. The model is also useful in establishing interceptor requirements.
Tolerating Tumors
Authors: Mueller Kristen L.
Published: May 2010

An immunotolerant microenvironment driven by chemokine expression contributes to tumor growth and spread.
Exclusive States
Authors: Foley John F.
Published: May 2010

Time-lapse microscopy reveals how Notch integrates signals from Delta molecules on the same cell with those from a neighboring cell.
A Trick of the Tail
Authors: Hurtley Stella M.
Published: May 2010

A synaptic vesicle protein must be membrane-anchored to stimulate fusion in vitro at physiological Ca
2+
concentrations.
Science Signaling
Podcast: 11 May 2010
Authors: Matus David Q. , Sherwood David R. , VanHook Annalisa M.
Published: May 2010

Genes that affect development of the nematode gonad are implicated in cell invasion and metastasis.
Inhibition of Dengue Virus RNA Synthesis by an Adenosine Nucleoside
Authors: Chen Yen-Liang , Yin Zheng , Duraiswamy Jeyaraj , Schul Wouter , Lim Chin Chin , Liu Boping , Xu Hao Ying , Qing Min , Yip Andy , Wang Gang , Chan Wai Ling , Tan Hui Pen , Lo Melissa , Liung Sarah , Kondreddi Ravinder Reddy , Rao Ranga , Gu Helen , He Handan , Keller Thomas H. , Shi Pei-Yong
Published: May 2010

We recently reported that (2
R
,3
R
,4
R
,5
R
)-2-(4-amino-pyrrolo[2,3-
d
]pyrimidin-7-yl)-3-ethynyl-5-hydroxy-methyl-tetrahydro-furan-3,4-diol is a potent inhibitor of dengue virus (DENV), with 50% effective concentration (EC
50
) and cytotoxic concentration (CC
50
) values of 0.7 μM and >100 μM, respectively. Here we describe the synthesis, structure-activity relationship, and antiviral characterization of the inhibitor. In an AG129 mouse model, a single-dose treatment of DENV-infected mice with the compound suppressed peak viremia and completely prevented death. Mode-of-action analysis using a DENV replicon indicated that the compound blocks viral RNA synthesis. Recombinant adenosine kinase could convert the compound to a monophosphate form. Suppression of host adenosine kinase, using a specific inhibitor (iodotubercidin) or small interfering RNA (siRNA), abolished or reduced the compound's antiviral activity in cell culture. Studies of rats showed that
14
C-labeled compound was converted to mono-, di-, and triphosphate metabolites
in vivo
. Collectively, the results suggest that this adenosine inhibitor is phosphorylated to an active (triphosphate) form which functions as a chain terminator for viral RNA synthesis.
Arylimidamide DB766, a Potential Chemotherapeutic Candidate for Chagas' Disease Treatment
Authors: Batista Denise da Gama Jaén , Batista Marcos Meuser , Oliveira Gabriel Melo de , Amaral Patrícia Borges do , Lannes-Vieira Joseli , Britto Constança Carvalho , Junqueira Angela , Lima Marli Maria , Romanha Alvaro José , Sales Junior Policarpo Ademar , Stephens Chad E. , Boykin David W. , Soeiro Maria de Nazaré Correia
Published: May 2010

Chagas' disease, a neglected tropical illness for which current therapy is unsatisfactory, is caused by the intracellular parasite
Trypanosoma cruzi
. The goal of this work is to investigate the
in vitro
and
in vivo
effects of the arylimidamide (AIA) DB766 against
T. cruzi
. This arylimidamide exhibits strong trypanocidal activity and excellent selectivity for bloodstream trypomastigotes and intracellular amastigotes (Y strain), giving IC
50
s (drug concentrations that reduce 50% of the number of the treated parasites) of 60 and 25 nM, respectively. DB766 also exerts striking effects upon different parasite stocks, including those naturally resistant to benznidazole, and displays higher activity
in vitro
than the reference drugs. By fluorescent and transmission electron microscopy analyses, we found that this AIA localizes in DNA-enriched compartments and induces considerable damage to the mitochondria. DB766 effectively reduces the parasite load in the blood and cardiac tissue and presents efficacy similar to that of benznidazole in mouse models of
T. cruzi
infection employing the Y and Colombian strains, using oral and intraperitoneal doses of up to 100 mg/kg/day that were given after the establishment of parasite infection. This AIA ameliorates electrocardiographic alterations, reduces hepatic and heart lesions induced by the infection, and provides 90 to 100% protection against mortality, which is similar to that provided by benznidazole. Our data clearly show the trypanocidal efficacy of DB766, suggesting that this AIA may represent a new lead compound candidate to Chagas' disease treatment.
Spatial and Temporal Patterns of Biocide Action against
Staphylococcus epidermidis
Biofilms
Authors: Davison William M. , Pitts Betsey , Stewart Philip S.
Published: May 2010

The dynamic antimicrobial action of chlorine, a quaternary ammonium compound, glutaraldehyde, and nisin within biofilm cell clusters of
Staphylococcus epidermidis
was investigated using time-lapse confocal scanning laser microscopy. The technique allowed for the simultaneous imaging of changes in biofilm structure and disruption of cellular membrane integrity through the loss of an unbound fluorophore loaded into bacterial cells prior to antimicrobial challenge. Each of the four antimicrobial agents produced distinct spatial and temporal patterns of fluorescence loss. The antimicrobial action of chlorine was localized around the periphery of biofilm cell clusters. Chlorine was the only antimicrobial agent that caused any biofilm removal. Treatment with the quaternary ammonium compound caused membrane permeabilization that started at the periphery of cell clusters, then migrated steadily inward. A secondary pattern superimposed on the penetration dynamic suggested a subpopulation of less-susceptible cells. These bacteria lost fluorescence much more slowly than the majority of the population. Nisin caused a rapid and uniform loss of green fluorescence from all parts of the biofilm without any removal of biofilm. Glutaraldehyde caused no biofilm removal and also no loss of membrane integrity. Measurements of biocide penetration and action time at the center of cell clusters yielded 46 min for 10 mg liter
−1
chlorine, 21 min for 50 mg liter
−1
chlorine, 25 min for the quaternary ammonium compound, and 4 min for nisin. These results underscore the distinction between biofilm removal and killing and reinforce the critical role of biocide reactivity in determining the rate of biofilm penetration.
Susceptibility of Gram-Negative Pathogens Isolated from Patients with Complicated Intra-Abdominal Infections in the United States, 2007-2008: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART)
Authors: Hoban Daryl J. , Bouchillon Samuel K. , Hawser Stephen P. , Badal Robert E. , LaBombardi Vincent J. , DiPersio Joseph
Published: May 2010

During 2007-2008, 1,036 Gram-negative bacilli were isolated from patients with complicated intra-abdominal infections in the United States. Against members of the family
Enterobacteriaceae
, the most active agents
in vitro
were ertapenem, imipenem, and amikacin, while the least active agent was ampicillin-sulbactam. Ertapenem and imipenem were active against all extended-spectrum-beta-lactamase (ESBL)-positive
Escherichia coli
. Antimicrobial resistance in Gram-negative bacilli isolated from patients with complicated intra-abdominal infections in the United States continues to increase.
Enterotoxigenic
Escherichia coli
Elicits Immune Responses to Multiple Surface Proteins
Authors: Roy Koushik , Bartels Scott , Qadri Firdausi , Fleckenstein James M.
Published: May 2010

Enterotoxigenic
Escherichia
coli
(ETEC) causes considerable morbidity and mortality due to diarrheal illness in developing countries, particularly in young children. Despite the global importance of these heterogeneous pathogens, a broadly protective vaccine is not yet available. While much is known regarding the immunology of well-characterized virulence proteins, in particular the heat-labile toxin (LT) and colonization factors (CFs), to date, evaluation of the immune response to other antigens has been limited. However, the availability of genomic DNA sequences for ETEC strains coupled with proteomics technology affords opportunities to examine novel uncharacterized antigens that might also serve as targets for vaccine development. Analysis of whole or fractionated bacterial proteomes with convalescent-phase sera can potentially accelerate identification of secreted or surface-expressed targets that are recognized during the course of infection. Here we report results of an immunoproteomics approach to antigen discovery with ETEC strain H10407. Immunoblotting of proteins separated by two-dimensional electrophoresis (2DE) with sera from mice infected with strain H10407 or with convalescent human sera obtained following natural ETEC infections demonstrated multiple immunoreactive molecules in culture supernatant, outer membrane, and outer membrane vesicle preparations, suggesting that many antigens are recognized during the course of infection. Proteins identified by this approach included established virulence determinants, more recently identified putative virulence factors, as well as novel secreted and outer membrane proteins. Together, these studies suggest that existing and emerging proteomics technologies can provide a useful complement to ongoing approaches to ETEC vaccine development.
Overexpression of therecAGene Decreases Oral but Not Intraperitoneal Fitness ofSalmonella enterica
Authors: Medina-Ruiz Laura , Campoy Susana , Latasa Cristina , Cardenas Paula , Alonso Juan Carlos , Barbé Jordi
Published: May 2010

Transcription of theSalmonella enterica recAgene is negatively controlled by the LexA protein, the repressor of the SOS response. The introduction of a mutation (recAo6869) in the LexA binding site, in the promoter region of theS. entericaATCC 14028recAgene, allowed the analysis of the effect that RecA protein overproduction has on the fitness of this virulent strain. The fitness of orally but not intraperitoneally inoculatedrecAo6869cells decreased dramatically. However, the SOS response of this mutant was induced normally, and there was no increase in the sensitivity of the strain toward DNA-damaging agents, bile salts, or alterations in pH. Nevertheless,S. enterica recAo6869cells were unable to swarm and their capacity to cross the intestinal epithelium was significantly reduced. The swarming deficiency inrecAo6869cells is independent of the flagellar phase. Moreover, swimming activity of therecAo6869strain was not diminished with respect to the wild type, indicating that the flagellar synthesis is not affected by RecA protein overproduction. In contrast, swarming was recovered in arecAo6869derivative that overproduced CheW, a protein known to be essential for this function. These data demonstrate that an equilibrium between the intracellular concentrations of RecA and CheW is necessary for swarming inS. enterica. Our results are the first to point out that the SOS response plays a critical role in the prevention of DNA damage by abolishing bacterial swarming in the presence of a genotoxic compound.
PERIODICALLY FORCED CHAOTIC SYSTEM WITH SIGNUM NONLINEARITY
Authors: SUN KEHUI , SPROTT J. C.
Published: May 2010

A sinusoidally-driven system with a simple signum nonlinearity term is investigated through an analytical analysis as well as dynamic simulation. To obtain the correct Lyapunov exponents, the signum function is replaced by a sharply varying continuous hyperbolic tangent function. By phase portraits, Poincaré sections and bifurcation diagrams, the rich dynamic behaviors of this system are demonstrated, such as an onion-like strange attractor, pitchfork and attractor merging bifurcations, period-doubling routes to chaos, and chaotic transients in the case of small damping. Moreover, the chaos persists as the damping is reduced to zero.
EXPONENTIAL STABILITY ANALYSIS OF NEURAL NETWORKS WITH VARIABLE DELAYS
Authors: TAN MAN-CHUN , ZHANG YAN , SU WEN-LI , ZHANG YU-NONG
Published: May 2010

Some sufficient conditions to ensure the existence, uniqueness and global exponential stability of the equilibrium point of cellular neural networks with variable delays are derived. These results extend and improve the existing ones in the literature. Two illustrative examples are given to demonstrate the effectiveness of our results.
EXPORT INITIATION IN SMALL LOCALLY-OWNED FIRMS FROM EMERGING ECONOMIES: THE ROLE OF PERSONAL FACTORS
Authors: WILLIAMS DENSIL A.
Published: May 2010

This paper examines the impact of personal factors in the decision of small, locally-owned firms from an emerging economy to enter into exporting. It drew on the logistic regression model to analyze the probability of a firm entering into exporting given its founder/owner possesses certain personal attributes. The results reveal personal attributes such as international job experience and foreign travel experience are the most critical in determining whether or not the firm exports. These results demonstrate demographic factors such as age and education level of the owner are less important and behavioral factors are more significant. Public policymakers interested in getting more firms to export can use these results as a guide to develop training centers that will encourage specific entrepreneurial behaviors germane to export initiation in small firms.
ENTREPRENEURSHIP IN TRANSITIONAL ECONOMIES: REVIEW AND INTEGRATION OF TWO DECADES OF RESEARCH
Authors: MANEV IVAN M. , MANOLOVA TATIANA S.
Published: May 2010

This review maps research on entrepreneurship in transitional economies since the start of institutional reforms. Data came from 129 academic journal articles published between 1990 and 2009. 62 articles reported research on macro (country) level, discussing the nature and speed of reform, credit constraints, assistance programs and the role of small business for economic development. 67 articles studied micro (firm) level factors, but only 14 of them employed data analytical methods to study what explains entrepreneurial success, suggesting a role for networking, industry experience and entrepreneurial orientation. We suggest more research on understanding the context of entrepreneurship, with a special focus on the informal institutional environment and industry structure. Also, future research can explore topics such as strategic agendas, opportunity identification and entrepreneurial cognition, which have been rare to date. We particularly emphasize the need for rigorous and replicable large-scale empirical studies.
DIFFERENCES BETWEEN FEMALE AND MALE ENTREPRENEURS' USE OF BOOTSTRAP FINANCING
Authors: NEELEY LYNN , VAN AUKEN HOWARD
Published: May 2010

Women-owned businesses are increasingly important to the U.S. economy in terms of numbers of firms owned, revenues and employment. Despite the growing role of female-owned business, the ownership, growth and size of female-owned firms is lower than that of male-owned firms. Differences in access to capital have been one reason attributed as an obstacle to women launching and growing small firms. This paper presents the results of an empirical study that examines differences of the use of bootstrap financing between female- and male-owned small firms. Research on the use of bootstrap financing among small firms is limited. The findings show that bootstrap finance methods were similar among female- and male-owned small firms; however, differences were found relative to age, education, sales and overdraft privileges. The results have implications for female entrepreneurs, support persons or agencies and government agencies providing assistance. Female owners should become more informed about financing options available beyond the traditional sources of capital. During periods of declining sales, especially during recessionary periods, female owners may rely on bootstrap sources to supplement capital needs, as well as proactively developing contingency plans for accessing bootstrap capital. These policies could be incorporated into training programs for female business owners. Educators and consultants could help female owners better understand financing alternatives and the importance if developing contingency plans. Government policy may be able to alleviate capital shortages through programs that better inform female entrepreneurs about the capital acquisition process.
MICROFINANCE IN CULTURES OF NON-REPAYMENT
Authors: EPSTEIN MARC J. , YUTHAS KRISTI
Published: May 2010

The microfinance industry seeks to alleviate poverty by providing business loans and related financial services to clients who are too small to be served profitably through the formal financial sector. Microbusiness lending is considered to be among the most powerful tools available for promoting entrepreneurial activity and economic development. However, a significant number of current and potential entrepreneurs remain untouched by microfinance. They live in regions considered to have cultures of non-repayment, which render them "unbankable." By better understanding non-repayment cultures and developing management strategies attuned to the unique attributes of these regions, the microfinance industry can effectively and profitably support these underserved entrepreneurs.
A COUNTY-LEVEL ASSESSMENT OF ENTREPRENEURSHIP AND ECONOMIC DEVELOPMENT IN APPALACHIA USING SIMULTANEOUS EQUATIONS
Authors: MOJICA MARIBEL N. , GEBREMEDHIN TESFA G. , SCHAEFFER PETER V.
Published: May 2010

Entrepreneurship is now recognized as a strategy to achieve economic growth in many regions. The goal of this paper is to increase the understanding of entrepreneurship's contributions to economic growth and its potential as a development strategy for a region, such as Appalachia, characterized by poverty and underdevelopment. Using data on Appalachian counties, a system of simultaneous equations is empirically estimated to measure the effects of entrepreneurship on economic growth and development. An expanded Carlino-Mills growth model is used where changes in population, employment and per capita income represent measures of growth. Proprietorship and firm formation rate data are used to measure entrepreneurial activity. The results show start-up businesses contribute significantly to determining population growth. Employment growth is positively affected by self-employment rates as well as by firm formation rates. In terms of policy implications, the paper recommends the creation of an environment to encourage entrepreneurial activity as a strategy to battle unemployment. It concludes that regional policy makers need to renew their efforts to support the growth of self-employment and sustain the existing firms.
Securing Elasticity in the Cloud
Authors: Owens Dustin
Published: May 2010

As somewhat of a technology-hype curmudgeon, I was until very recently in the camp that believed cloud computing was not much more than the latest marketing-driven hysteria for an idea that has been around for years. Outsourced IT infrastructure services, aka IaaS (Infrastructure as a Service), has been around since at least the 1980s, delivered by the telecommunication companies and major IT outsourcers. Hosted applications, aka PaaS (Platform as a Service) and SaaS (Software as a Service), were in vogue in the 1990s in the form of ASPs (application service providers).
An Old Luddite Discovers Twitter
Authors: Schank Roger
Published: May 2010

A business associate of mine told me I must sign up for Facebook. I figured he probably had an investment in it and if I wanted his business, I'd better do it. So we became "friends." But I didn't see any value in Facebook whatsoever. Then I discovered Twitter, where everything is different.
What Do Training Awards Tell Us?
Authors: Ellet William
Published: May 2010

People around the globe love ratings, from "Car of the Year -- Slovakia" and "Los Grandes De Nuevo Mexico Music Awards" to Cook's Illustrated's ratings of catsup. Corporate trainers are no exception. We pay attention to awards contests for training products and often make choices based on them. The contests can serve a valuable function. They help make sense of the sprawling training industry, which is awash in products but has few well-established authorities to guide buyers' choices. Contests are also popular with companies that run them. The reason is simple: they make money.
Understanding the values of mobile technology in education
Authors: Sheng Hong , Siau Keng , Nah Fiona Fui-Hoon
Published: May 2010

Mobile technology has mobilized the human interaction in all dimensions by supporting mobile collaboration. As collaboration is key to learning in today's educational environment, mobile technology has tremendous potential in supporting and improving education and its delivery. Given that mobile technology for education is a new phenomenon that is gaining popularity, the values of using mobile technology to support education need to be further researched and better understood. In this research, we used the Value-Focused Thinking approach to interview students and instructors to identify the values of education that are enabled by mobile technology. These values are represented in the form of a means-ends objective network that not only captures the values of education facilitated by mobile technology but also depicts the relationships between these values. The means-ends objective network derived from this research can serve as a conceptual foundation for future studies and provide useful guidelines to practitioners for implementation of mobile technology in education.
The intangibility of e-services
Authors: Featherman Mauricio S. , Wells John D.
Published: May 2010

This study examines the construct of intangibility within the e-services context and clarifies why business-to-consumer services are made more intangible when they are virtualized and offered as Internet e-services. Clarifying the intangibility of e-services and examining its consequents is important as service providers seek to encourage consumers to use lower-cost e-services. This research specifically develops theory to explain how and why an e-service's intangibility can increase consumer beliefs that it is risky to use, and furthermore removes the risk-reducing effect of the e-service's perceived ease of use. These consequents of an e-service's intangibility are important to clarify because e-service's usage is based in part on beliefs that they are safe and easy to use. Results from a structural equation model-based analysis of consumer survey data supported these two hypothesized effects. More specifically, the performance, financial, and privacy risk dimensions were most affected by consumers' experience of mental intangibility regarding the e-service. In addition, a qualification of a previously reported risk-reducing strategy for e-service providers was identified. Only when consumers' mental intangibility was low (i.e., they had a clear mental picture of the e-service) did the e-service's perceived ease of use function as a risk-reducing factor. An e-service's intangibility may indirectly impede consumer usage of a range of e-services. Theoretical and practical implications are offered.
Limitations of conventional approaches to identify myocyte nuclei in histologic sections of the heart
Authors: Ang Keng-Leong , Shenje Lincoln T. , Reuter Sean , Soonpaa Mark H. , Rubart Michael , Field Loren J. , Galiñanes Manuel
Published: May 2010

Accurate nuclear identification is crucial for distinguishing the role of cardiac myocytes in intrinsic and experimentally induced regenerative growth of the myocardium. Conventional histologic analysis of myocyte nuclei relies on the optical sectioning capabilities of confocal microscopy in conjunction with immunofluorescent labeling of cytoplasmic proteins such as troponin T, and dyes that bind to double-strand DNA to identify nuclei. Using heart sections from transgenic mice in which the cardiomyocyte-restricted α-cardiac myosin heavy chain promoter targeted the expression of nuclear localized β-galactosidase reporter in >99% of myocytes, we systematically compared the fidelity of conventional myocyte nuclear identification using confocal microscopy, with and without the aid of a membrane marker. The values obtained with these assays were then compared with those obtained with anti-β-galactosidase immune reactivity in the same samples. In addition, we also studied the accuracy of anti-GATA4 immunoreactivity for myocyte nuclear identification. Our results demonstrate that, although these strategies are capable of identifying myocyte nuclei, the level of interobserver agreement and margin of error can compromise accurate identification of rare events, such as cardiomyocyte apoptosis and proliferation. Thus these data indicate that morphometric approaches based on segmentation are justified only if the margin of error for measuring the event in question has been predetermined and deemed to be small and uniform. We also illustrate the value of a transgene-based approach to overcome these intrinsic limitations of identifying myocyte nuclei. This latter approach should prove quite useful when measuring rare events.
Activation of BKCa channel is associated with increased apoptosis of cerebrovascular smooth muscle cells in simulated microgravity rats
Authors: Xie Man-Jiang , Ma Yu-Guang , Gao Fang , Bai Yun-Gang , Cheng Jiu-Hua , Chang Yao-Ming , Yu Zhi-Bin , Ma Jin
Published: May 2010

Cerebral arterial remodeling is one of the critical factors in the occurrence of postspaceflight orthostatic intolerance. We hypothesize that large-conductance calcium-activated K+ (BKCa) channels in vascular smooth muscle cells (VSMCs) may play an important role in regulating cerebrovascular adaptation during microgravity exposure. The aim of this work was to investigate whether activation of BKCa channels is involved in regulation of apoptotic remodeling of cerebral arteries in simulated microgravity rats. In animal studies, Sprague-Dawley rats were subjected to 1-wk hindlimb unweighting to simulate microgravity. Alterations of BKCa channels in cerebral VSMCs were investigated by patch clamp and Western blotting; apoptosis was assessed by electron microscopy and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling (TUNEL). To evaluate the correlation of BKCa channel and apoptosis, channel protein and cell nucleus were double-stained. In cell studies, hSloα+β1 channel was coexpressed into human embryonic kidney 293 (HEK293) cells to observe the effects of BKCa channels on apoptosis. In rats, enhanced activities and expression of BKCa channels were found to be correlated with increased apoptosis in cerebral VSMCs after simulated microgravity. In transfected HEK293 cells, activation of cloned BKCa channel induced apoptosis, whereas inhibition of cloned BKCa channel decreased apoptosis. In conclusion, activation of BKCa channels is associated with increased apoptosis in cerebral VSMCs of simulated microgravity rats.
Advance Planning in Sequential Pick–and–Place Tasks
Authors: Hesse Constanze , Deubel Heiner
Published: May 2010

It has been suggested that the kinematics of a reach–to–grasp movement, performed within an action sequence, vary depending on the action goal and the properties of subsequent movement segments (action context effect). The aim of this study was to investigate whether the action context also affects action sequences that consist of several grasping movements directed toward different target objects. Twenty participants were asked to perform a sequence in which they grasped a cylinder, placed it into a target area, and subsequently grasped and displaced a target bar of a certain orientation. We specifically tested whether the orientation of the target bar being grasped in the last movement segment influenced the grip orientation adapted to grasp and place the cylinder in the preceding segments. When all movement segments within the sequence were easy to perform, results indeed showed that grip orientation chosen in the early movement segments depended on the forthcoming motor demands, suggesting a holistic planning process. In contrast, high accuracy demands in specifying a movement segment reduced the ability of the motor system to plan and organize the movement sequence into larger chunks, thus causing a shift toward sequential performance. Additionally, making the placing task more difficult resulted in prolonged reaction times and increased the movement times of all other movement segments.
The Role of V1 Surround Suppression in MT Motion Integration
Authors: Tsui James M. G. , Hunter J. Nicholas , Born Richard T. , Pack Christopher C.
Published: May 2010

Neurons in the primate extrastriate cortex are highly selective for complex stimulus features such as faces, objects, and motion patterns. One explanation for this selectivity is that neurons in these areas carry out sophisticated computations on the outputs of lower-level areas such as primary visual cortex (V1), where neuronal selectivity is often modeled in terms of linear spatiotemporal filters. However, it has long been known that such simple V1 models are incomplete because they fail to capture important nonlinearities that can substantially alter neuronal selectivity for specific stimulus features. Thus a key step in understanding the function of higher cortical areas is the development of realistic models of their V1 inputs. We have addressed this issue by constructing a computational model of the V1 neurons that provide the strongest input to extrastriate cortical middle temporal (MT) area. We find that a modest elaboration to the standard model of V1 direction selectivity generates model neurons with strong end-stopping, a property that is also found in the V1 layers that provide input to MT. With this computational feature in place, the seemingly complex properties of MT neurons can be simulated by assuming that they perform a simple nonlinear summation of their inputs. The resulting model, which has a very small number of free parameters, can simulate many of the diverse properties of MT neurons. In particular, we simulate the invariance of MT tuning curves to the orientation and length of tilted bar stimuli, as well as the accompanying temporal dynamics. We also show how this property relates to the continuum from component to pattern selectivity observed when MT neurons are tested with plaids. Finally, we confirm several key predictions of the model by recording from MT neurons in the alert macaque monkey. Overall our results demonstrate that many of the seemingly complex computations carried out by high-level cortical neurons can in principle be understood by examining the properties of their inputs.
Computational Analysis of the Impact of Chronic Stress on Intrinsic and Synaptic Excitability in the Hippocampus
Authors: Narayanan Rishikesh , Chattarji Sumantra
Published: May 2010

Dendritic atrophy and impaired long-term synaptic potentiation (LTP) are hallmarks of chronic stress-induced plasticity in the hippocampus. It has been hypothesized that these disparate structural and physiological correlates of stress lead to hippocampal dysfunction by reducing postsynaptic dendritic surface, thereby adversely affecting the availability of synaptic inputs and suppressing LTP. Here we examine the validity of this framework using biophysical models of hippocampal CA3 pyramidal neurons. To statistically match with the experimentally observed region specificity of stress-induced atrophy, we use an algorithm to systematically prune three-dimensional reconstructions of CA3 pyramidal neurons. Using this algorithm, we build a biophysically realistic computational model to analyze the effects of stress on intrinsic and synaptic excitability. We find that stress-induced atrophy of CA3 dendrites leads to an increase in input resistance, which depends exponentially on the percentage of neuronal atrophy. This increase translates directly into higher spiking frequencies in response to both somatic current injections and synaptic inputs at various locations along the dendritic arbor. Remarkably, we also find that the dendritic regions that manifest atrophy-induced synaptic hyperexcitability are governed by the region specificity of the underlying dendritic atrophy. Coupled with experimentally observed modulation of N-methyl-d-aspartate receptor currents, such hyperexcitability could tilt the balance of plasticity mechanisms in favor of synaptic potentiation over depression. Thus paradoxically, our results suggest that stress may impair hippocampal learning and memory, not by directly inhibiting LTP, but because of stress-induced facilitation of intrinsic and synaptic excitability and the consequent imbalance in bidirectional synaptic plasticity.
Presynaptic Interneuron Subtype- and Age-Dependent Modulation of GABAergic Synaptic Transmission by β-Adrenoceptors in Rat Insular Cortex
Authors: Koyanagi Yuko , Yamamoto Kiyofumi , Oi Yoshiyuki , Koshikawa Noriaki , Kobayashi Masayuki
Published: May 2010

β-Adrenoceptors play a crucial role in the regulation of taste aversion learning in the insular cortex (IC). However, β-adrenergic effects on inhibitory synaptic transmission mediated by γ-aminobutyric acid (GABA) remain unknown. To elucidate the mechanisms of β-adrenergic modulation of inhibitory synaptic transmission, we performed paired whole cell patch-clamp recordings from layer V GABAergic interneurons and pyramidal cells of rat IC aged from postnatal day 17 (PD17) to PD46 and examined the effects of isoproterenol, a β-adrenoceptor agonist, on unitary inhibitory postsynaptic currents (uIPSCs). Isoproterenol (100 μM) induced facilitating effects on uIPSCs in 33.3% of cell pairs accompanied by decreases in coefficient of variation (CV) of the first uIPSC amplitude and paired-pulse ratio (PPR) of the second to first uIPSC amplitude, whereas 35.9% of pairs showed suppressive effects of isoproterenol on uIPSC amplitude obtained from fast spiking (FS) to pyramidal cell pairs. Facilitatory effects of isoproterenol were frequently observed in FS–pyramidal cell pairs at ≥PD24. On the other hand, isoproterenol suppressed uIPSC amplitude by 52.3 and 39.8% in low-threshold spike (LTS)–pyramidal and late spiking (LS)–pyramidal cell pairs, respectively, with increases in CV and PPR. The isoproterenol-induced suppressive effects were blocked by preapplication of 100 μM propranolol, a β-adrenoceptor antagonist. There was no significant correlation between age and changes of uIPSCs in LTS–/LS–pyramidal cell pairs. These results suggest the presence of differential mechanisms in presynaptic GABA release and/or postsynaptic GABAA receptor-related assemblies among interneuron subtypes. Age- and interneuron subtype-specific β-adrenergic modulation of IPSCs may contribute to experience-dependent plasticity in the IC.