bluuebunny/crossref_metadata_2025 huggingface dataset:
Longterm follow‐up of diode laser transscleral cyclophotocoagulation in the treatment of refractory glaucoma
Authors: Frezzotti Paolo , Mittica Vincenzo , Martone Gianluca , Motolese Ilaria , Lomurno Luca , Peruzzi Sabrina , Motolese Edoardo
Published: April 2009

Purpose:  This prospective study was conducted to evaluate the efficacy and safety of transscleral diode laser cyclophotocoagulation (TDLCP) in advanced refractory glaucoma.

Methods:  A total of 124 eyes in 121 patients with advanced glaucoma refractory to medical treatment were treated consecutively with TDLCP. Success was defined as final intraocular pressure (IOP) of 5−21 mmHg in eyes with visual acuity (VA) of more than hand movements (HM) and relief of pain in eyes with VA of HM or less, including blind eyes.

Results:  Mean patient age was 65.6 ± 17.1 years (range 14–91 years). Mean follow‐up was 17 ± 14.6 months (range 3–42 months). Mean pretreatment IOP was 29.9 ± 8.4 mmHg (range 17–58 mmHg) and IOP at last follow‐up was 20.8 ± 8 mmHg (range 6–45 mmHg) (p < 0.001). The number of laser applications (mean 9.2 ± 2.8, range 4–15) and maximal laser power (mean 2.01 ± 0.22 mW, range 1.3–3.0 mW) were not associated with lower postoperative IOP. Intraocular pressure of ≤ 21 mmHg was recorded in 63.0% of eyes at the last follow‐up visit. Overall, 28 (21.7%) eyes required at least one retreatment. No phthisis bulbi or persistent hypotonia developed.

Conclusions:  TDLCP is an effective and safe method for the treatment of advanced refractory glaucoma, although repeated treatments are often necessary.
Organizational Self‐Censorship: Corporate Sponsorship, Nonprofit Funding, and the Educational Experience*
Authors: GRAY GARRY C. , BISHOP KENDZIA VICTORIA
Published: April 2009

La dépendance croissante du secteur privé envers la commandite a eu des conséquences sur la gouvernance des organismes sans but lucratif (OSBL). La recherche traditionnelle sur le financement a pris un angle d'observation essentiellement positif, montrant que les OSBL peuvent trouver des occasions d'influencer les intérêts de leurs bailleurs de fonds de manière à ce qu'ils deviennent plus compatibles avec la mission de l'OSBL. Dans cet article, les auteurs s'inspirent de ce travail en fournissant un examen plus nuancé de l'intermédiaire dans l'OSBL. Plus précisément, les auteurs introduisent une forme négative d'intermédiaire connue sous le nom d'autocensure organisationnelle. En examinant l'autocensure, ils montrent que les OSBL devraient plutôt redéfinir leurs propres buts de manière à attirer les bailleurs de fonds du secteur privé.

Increasing reliance on corporate sponsorship has impacted the governance of nonprofit organizations. Traditional research on funding has taken a predominately positive vantage point, expressing that nonprofit organizations may find opportunities to influence their funder's interests such that they become more compatible with the nonprofit organization's mission. In this article, we build upon this work by providing a more nuanced examination of agency in the nonprofit organization. Specifically, we introduce a negative form of agency known as organizational self‐censorship. By examining self‐censorship, we reveal that nonprofit organizations may instead redefine their own goals in order to appeal to private sector funders.
Rare association of Parvovirus B19 infection in Kikuchi's lymphadenitis in Korea
Authors: Shin Bongkyung , Choi Jung Woo , Kim Insun
Published: April 2009

Background and aims:To determine the role of parvovirus B19 (PVB19) in Kikuchi's lymphadenitis of Korean patients.Methods:We detected PVB19 DNA by polymerase chain reaction, and confirmed by DNA sequencing, and immunohistochemical stain in 67 histologically confirmed cases.Results:Male to female ratio was 1:3 and the mean age was 24.6 years. The cases were classified into proliferative type (60.8%), necrotizing type (33.3%), and xanthomatous type (5.7%) and the duration of the disease was well correlated with progression from proliferative, necrotizing and xanthomatous types. PVB19 was detected in only one patient, who was a 33‐year old woman and did not show any specific clinicopathologic characteristics from other patients.Conclusions:Although parvovirus may not play an important role in Kikuchi's lymphadenitis in Korean patients, PVB19 may be still considered one of the agents, relating with Kikuchi's lymphadenitis in Korea. In contrast to the previous studies, we concluded that the association of PVB19 in Kikuchi's lymphadenitis may be an incidental finding rather than a constant features of this disease.
Peripheral Nucleated Red Blood Cells as a Prognostic Indicator in Heatstroke in Dogs
Authors: Aroch I. , Segev G. , Loeb E. , Bruchim Y.
Published: April 2009

Background: Heatstroke in dogs is often fatal and is associated with a high prevalence of secondary complications. Peripheral nucleated red blood cells (NRBC) occur in dogs with heatstroke, but their association with complications and the outcome is unclear.

Hypothesis: Peripheral NRBC are common in dogs with heatstroke and have prognostic significance.

Animals: Forty client‐owned dogs with naturally occurring heatstroke.

Methods: Prospective, observational study. Dogs were followed from presentation to discharge or death. Serum biochemistry and coagulation tests were performed at presentation. CBC and evaluation of peripheral blood smears were performed at presentation and every 12 hours. The relative and the absolute NRBC numbers were calculated.

Results: Presence of NRBC was observed in 36/40 (90%) of the dogs at presentation. Median relative and absolute NRBC were 24 cells/100 leukocytes (range 0–124) and 1.48 × 103/μL (range 0.0–19.6 × 103/μL), respectively. Both were significantly higher in nonsurvivors (22) versus survivors (18) and in dogs with secondary renal failure and DIC versus those without these complications. Receiver operator curve analysis of relative NRBC at presentation as a predictor of death had an area under curve of 0.92. A cut‐off point of 18 NRBC/100 leukocytes corresponded to a sensitivity and specificity of 91 and 88% for death.

Conclusions and Clinical Importance: Relative and absolute numbers of peripheral NRBC are clinically useful, correlate with the secondary complications, and are sensitive and specific markers of death in dogs with heatstroke, although they should never be used as a sole prognostic indicator nor should they replace clinical assessment.
Cerebrospinal Fluid PCR and Antibody Concentrations against Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in Dogs with Neurological Signs
Authors: Jäderlund K.H. , Bergström K. , Egenvall A. , Hedhammar Å.
Published: April 2009

Background: The tick‐borne bacteria Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum have been suspected to cause neurological signs in dogs. Diagnosis often has been made based on positive antibody titers in serum of dogs with neurological signs, but a high seroprevalence in dogs in at‐risk populations makes diagnosis difficult.

Objective: To determine if the neurological signs in dogs examined were caused by any of these bacteria.

Animals: Fifty‐four dogs presented to a board‐certified neurologist.

Methods: Prospective study. We divided dogs into 2 groups: those with inflammatory diseases of the central nervous system (CNS) and those with neurological signs from other diseases. Blood and cerebrospinal fluid (CSF) from all dogs were analyzed.

Results: Dogs with inflammatory CNS diseases showed no serum antibodies against any of the agents. Among dogs with neurological signs from other diseases, 10.3% had serum antibodies for B. burgdorferi sl and 20.5% for A. phagocytophilum. All blood samples analyzed for bacterial deoxyribonucleic acid (DNA) and all CSF analyzed for antibodies and bacterial DNA for the 2 agents were negative.

Conclusions and Clinical Importance: Based on this study, these bacteria are unlikely causes of neurologic disease in dogs and the presence of serum antibodies alone does not document or establish a definitive diagnosis of CNS disease caused by these organisms. Dogs that have neurologic disease and corresponding serum antibodies against these agents should have additional tests performed to assess for other potential etiologies of the signs.
Exact Solutions for the Generalized Euler’s Problem
Authors: Li Q. S.
Published: April 2009

This paper is concerned with buckling analysis of a nonuniform column with classical∕nonclassical boundary conditions and subjected to a concentrated axial force and distributed variable axial loading, namely, the generalized Euler’s problem. Exact solutions are derived for the buckling problem of nonuniform columns with variable flexural stiffness and under distributed variable axial loading expressed in terms of polynomial functions. Then, more complicated buckling problems are considered such as that the distribution of flexural stiffness of a nonuniform column is an arbitrary function, and the distribution of axial loading acting on the column is expressed as a functional relation with the distribution of flexural stiffness and vice versa. The governing equation for such problems is reduced to Bessel equations and other solvable equations for seven cases by means of functional transformations. A class of exact solutions for the generalized Euler’s problem involved a nonuniform column subjected to an axial concentrated force and axially distributed variable loading is obtained herein for the first time in literature.
Parametric Resonance of a Two Degrees-of-Freedom System Induced by Bounded Noise
Authors: Zhu Jinyu , Xie W.-C. , So Ronald M. C. , Wang X. Q.
Published: April 2009

The dynamic stability of a two degrees-of-freedom system under bounded noise excitation with a narrowband characteristic is studied through the determination of moment Lyapunov exponents. The partial differential eigenvalue problem governing the moment Lyapunov exponent is established. For weak noise excitations, a singular perturbation method is employed to obtain second-order expansions of the moment Lyapunov exponents and Lyapunov exponents, which are shown to be in good agreement with those obtained using Monte Carlo simulation. The different cases when the system is in subharmonic resonance, combination additive resonance, and combined resonance in the absence of noise, respectively, are considered. The effects of noise and frequency detuning on the parametric resonance are investigated.
Acoustic Radiation From a Laminated Composite Plate Excited by Longitudinal and Transverse Mechanical Drives
Authors: Yin X. W. , Cui H. F.
Published: April 2009

Analytical expressions are derived for the vibration and far-field acoustic radiation from a fluid-loaded laminated composite plate, which is excited by three types of mechanical drives: point, line, and uniformly distributed forces in longitudinal and transverse directions. Through numerical results, it is shown that the lamination schemes of the laminated composite plate play an important role in its far-field acoustic radiation, especially when the plies of the plate are asymmetric with its middle plane. This paper would help better understand the main mechanism of acoustic radiation from laminated composite plates, which has not been adequately addressed in its companion paper (Yin, et al., 2007, “Acoustic Radiation From a Laminated Composite Plate Reinforced by Doubly Periodic Parallel Stiffeners,” J. Sound Vibrat., 306, pp. 877–889).
An Experimental Study on the Influence of Vortex Generators on the Shock-Induced Boundary Layer Separation at M=1.4
Authors: Zare Shahneh A. , Motallebi F.
Published: April 2009

The results of an investigation into the effects that sub-boundary layer vortex generators (SBVGs) have on reducing normal shock-induced turbulent boundary layer separation are presented. The freestream Mach number and Reynolds number were M=1.45 and R=15.9×106/m, respectively. Total pressure profiles, static pressure distributions, surface total pressure (Preston pressure) distributions, oil flow visualization, and Schlieren photographs were used in the result analysis. The effects of SBVG height and the location upstream of the shock were investigated. A novel tetrahedron shape SBVG with different lengths (30 mm and 60 mm) was used for these experiments. The effect of streamwise location of the longer SBVG on the interaction was also investigated. The location of the shock wave was controlled by an adjustable choke mechanism located downstream of the working section. The results show that an increase in the distance for the longer SBVG from 17.4δR to 25.5δR did not remove the separation entirely, but the shorter SBVG provided higher total pressure distribution within the boundary layer in the recovery region. This also provided a healthier boundary layer profile downstream of the interaction region with lower displacement thickness and shape factor.
Thermal Optimization of a Microchannel Heat Sink With Trapezoidal Cross Section
Authors: Husain Afzal , Kim Kwang-Yong
Published: April 2009

A microchannel heat sink shape optimization has been performed using response surface approximation. Three design variables related to microchannel width, depth, and fin width are selected for optimization, and thermal resistance has been taken as objective function. Design points are chosen through a three-level fractional factorial design of sampling methods. Navier–Stokes and energy equations for steady, incompressible, and laminar flow and conjugate heat transfer are solved at these design points using a finite volume solver. Solutions are carefully validated with the analytical and experimental results and the values of objective function are calculated at the specified design points. Using the numerically evaluated objective-function values, a polynomial response surface model is constructed and the optimum point is searched by sequential quadratic programming. The process of shape optimization greatly improves the thermal performance of the microchannel heat sink by decreasing thermal resistance of about 12% of the reference shape. Sensitivity of objective function to design variables has been studied to utilize the substrate material efficiently.
Laser Soldering of Fine Pitch QFP Devices Using Lead-Free Solders
Authors: Han Zongjie , Xue Songbai , Wang Jianxin , Zhang Xin , Yu Shenglin , Zhang Liang
Published: April 2009

In this paper, soldering experiments of fine pitch quad flat package (QFP) devices were carried out when soldered with Sn–Ag–Cu and Sn–Cu–Ni lead-free solders by means of diode laser soldering system, and compared with the experimental results soldered with Sn–Pb solders and with infrared (IR) reflow soldering method. The results indicate that under the conditions of laser continuous scanning mode and the fixed laser soldering time, an optimal power is obtained when the optimal mechanical properties of QFP microjoints are achieved. Mechanical properties of QFP microjoints soldered with laser soldering system are better than that of QFP microjoints soldered with IR soldering method. Results also indicate that adding rare earth element Ce to Sn–Ag–Cu and Sn–Cu–Ni lead-free solders improves mechanical properties of QFP microjoints, and the optimal amount of Ce is about 0.03%.
Effect of Variable Heating Load on the Refrigerant Distribution of a Dual Cold-Plate System
Authors: Tien Cheng-Wei , Yu Kun-Huang , Sheu Wen-Junn , Wang Chi-Chuan
Published: April 2009

This study examines the refrigerant distribution of a dual cold-plate system subject to the influence of heating load, using a R-134a based vapor compression system with a nominal capacity ranging from 50 W to 250 W. The cold plate is of identical configuration. Initially, test is performed under an equal heating load for each cold plate (70 W), which then gives rise to a uniform distribution and equal outlet superheat condition. For an unequal heating load, it is found that the distribution of mass flowrate subject to the influence of heating load is strongly related to the outlet states of the two cold plates. For the condition where one of the cold plates is in superheated state while the other is in saturated state, the mass flowrate for the fixed heating load is lower than that of smaller heating load, and the difference increases when the heating load gets smaller due to the influence of accelerational pressure drop. A maximum of 17% difference is seen at a loading ratio of 0.571 (40 W/70 W). For the condition where both outlet states of the cold plate are at superheated states, the mass flowrate for the fixed heating load is marginally higher than that of the smaller heating load, and the difference is insensitive to the increase in heating load. For this situation, the effect of accelerational pressure is negligible, and it is mainly attributed to two-phase/single-phase distribution pertaining to the effect of heating load.
Electromigration Reliability of 96.5Sn–3Ag–0.5Cu Flip-Chip Solder Joints With Au/Ni/Cu or Cu Substrate Pad Metallization
Authors: Lai Yi-Shao , Chiu Ying-Ta , Lee Chiu-Wen
Published: April 2009

Designed experiments were conducted in this paper to study the effect of Au/Ni/Cu or Cu substrate pad metallization on the electromigration reliability of 96.5Sn–3Ag–0.5Cu flip-chip solder joints with Ti/Ni(V)/Cu under bump metallurgy (UBM) under a current stressing condition with an average current density of around 5 kA/cm2 at an ambient temperature of 150°C. Cross-sectional observations on current-stressed solder joints indicate that although Cu metallization results in severe voiding compared with Au/Ni/Cu metallization on the substrate side of the solder joint, the dominant failure has been identified as UBM consumption, and test vehicles with Cu metallization exhibit better electromigration reliability than those with Au/Ni/Cu metallization. The stronger durability against current stressing for test vehicles with Cu metallization may attribute to the lower UBM consumption rate due to the continuous Cu diffusion toward UBM as a result of the concentration gradient. The consumption of UBM is faster for test vehicles with Au/Ni/Cu metallization because Cu diffusion from the substrate pad is retarded by the Ni barrier.
Evaluation of Time-Independent and Time-Dependent Strains of Lead-Free Solder by Stepped Ramp Loading Test
Authors: Ohguchi Ken-ichi , Sasaki Katsuhiko , Aso Setsuo
Published: April 2009

This paper proposes a method to estimate basic material constants in an elasto-plastic-creep constitutive model for lead-free solders by conducting only a tensile test. The test employs a stepped ramp wave loading, which repeats instantaneous strain and strain maintenance. Time-independent strains are obtained from the stress-strain relations at the instantaneously strained parts, while the time-dependent strains are obtained from the stress-time relations during the strain maintaining periods. Based on the obtained time-independent and time-dependent strains, the values of the material constants in the elasto-plastic-creep model proposed by the authors are determined. Simulations of the viscoplastic deformations of a Sn–3.0Ag–0.5Cu solder alloy are also conducted to verify the validity of the proposed method.
Passive Cooling of Protruding Electronic Components by Latent Heat of Fusion Storage
Authors: Faraji Mustapha , El Qarnia Hamid
Published: April 2009

The aim of the present work is to study the thermal performance of a hybrid heat sink used for cooling management of protruding substrate-mounted electronic chips. The power generated in electronic chips is dissipated in phase change material (PCM) (n-eicosane with melting temperature Tm=36°C) that filled a rectangular enclosure. The advantage of using this cooling strategy is that the PCMs are able to absorb a high amount of heat generated by electronic component (EC) without acting the fan, during the charging process (melting of the PCM). A two-dimensional mathematical model was developed in order to analyze and optimize a heat sink. The governing equations for masse, momentum, and energy transport were developed and discretized by using the volume control approach. The resulting algebraic equations were next solved iteratively by using tri diagonal matrix algorithm. A series of numerical investigations were conducted in order to examine the effects of the heat generation based Rayleigh number, Ra, and the position of the bottom electronic component, Lh, on the thermal behavior of the proposed cooling system. Results are obtained for velocity and temperature distributions, maximum temperature heat sources, percentage contribution of plate (substrate) heat conduction on the heat removal from electronic components, temperature profile within finite conductive plate and local heat flux density at the plate—modules/PCM interface. The effect of these two key parameters on the electronic component working time (time required by electronic components to reach a critical temperature, Tcr) was analyzed.
Heat Transfer Limitation of a Micro Heat Pipe
Authors: Shukla K. N.
Published: April 2009

An analytical expression for the heat transport capability of micro heat pipe is derived. The vapor continuum limitation has been considered in deriving the heat transport capability of a micro heat pipe. As the micro heat pipe uses sharp-cornered square, triangular, or other polygonal channels that can serve as capillary arteries, its transport capability depends on the capillary limit. It has been shown that the operating limit of the micro heat pipe depends on the vapor continuum limitation, capillary limit, and the gravity.
Fluid-to-Fluid Spot-to-Spreader (F2/S2) Hybrid Heat Sink for Integrated Chip-Level and Hot Spot-Level Thermal Management
Authors: Green Craig , Fedorov Andrei G. , Joshi Yogendra K.
Published: April 2009

An innovative heat sink design aimed at meeting both the hot spot and large background heat flux requirements of next generation integrated circuits is presented. The heat sink design utilizes two separate unmixed fluids to meet the cooling requirements of the chip with one fluid acting as a fluidic spreader dedicated to cooling the hot spots only, while the second fluid serves as both a coolant for the background heat fluxes and an on-chip regenerator for the hot spot fluid. In this paper the conceptual heat sink design is presented and its theoretical capabilities are explored through optimization calculations and computational fluid dynamics simulations. It has been shown that through close coupling of the two thermal fluids the proposed hybrid heat sink can theoretically remove hot spot heat fluxes on the order of 1 kW/cm2 and background heat fluxes up to 100 W/cm2 in one compact and efficient package. Additionally, it has been shown that the F2/S2 design can handle these thermal loads with a relatively small pressure drop penalty, within the realm of existing micropump technologies. Finally, the feasibility of the F2/S2 design was demonstrated experimentally by modifying a commercially available, air-cooled aluminum heat sink to accommodate an integrated hot spot cooling system and fluidic spreader. The results of these experiments, where the prototype heat sink was able to remove hot spot heat fluxes of up to 365 W/cm2 and background heat fluxes of up to 20 W/cm2, are reported.
The Energy Absorption Characteristics of Square Mild Steel Tubes With Multiple Induced Circular Hole Discontinuities—Part II: Numerical Simulations
Authors: Bodlani S. B. , Chung Kim Yuen S. , Nurick G. N.
Published: April 2009

This paper is Part II of a two-part article and presents the results of numerical simulations conducted to investigate the energy absorption characteristics of square tubes subjected to dynamic axial loading. Part I reports the experimental results of both quasistatic and dynamic tests. The validated model is used to study the crushing characteristics of tubes with multiple induced circular hole discontinuities using the finite element package ABAQUS/EXPLICIT version 6.4-6. Holes of diameter 17 mm are used as crush initiators, which are laterally drilled into the tube wall to form opposing hole pairs. Holes of diameters 12.5 mm and 25 mm are also used to assess the effects of hole diameter on energy absorption. Two hole spacing configurations are investigated, one in which the hole pairs are placed at regular intervals of 50 mm along the tube wall and another in which the hole pairs are spaced symmetrically along the tube length. Holes are also drilled on either two or all four opposing tube walls. The number of holes is varied from 2 to 10. The results indicate that the introduction of the holes decreases the initial peak force. However, an increase in the number of holes, beyond two holes, does not further significantly decrease the initial peak force. A study of the crushing history of the tubes reveals that crushing is initiated at the location of the holes. The results also indicate that the type of hole spacing determines how crushing is initiated at the hole locations. The model satisfactorily predicts the resultant collapse shapes but overpredicts the crushed distance.
Complementation of the
fadA
Mutation in
Fusobacterium nucleatum
Demonstrates that the Surface-Exposed Adhesin Promotes Cellular Invasion and Placental Colonization
Authors: Ikegami Akihiko , Chung Peter , Han Yiping W.
Published: April 2009

Fusobacterium nucleatum
is a gram-negative oral anaerobe implicated in periodontal disease and adverse pregnancy outcome. The organism colonizes the mouse placenta, causing localized infection and inflammation. The mechanism of placental colonization has not been elucidated. Previous studies identified a novel adhesin from
F. nucleatum
, FadA, as being involved in the attachment and invasion of host cells. The
fadA
deletion mutant
F. nucleatum
12230 US1 was defective in host cell attachment and invasion in vitro, but it also exhibited pleiotropic effects with altered cell morphology and growth rate. In this study, a
fadA
-complementing clone,
F. nucleatum
12230 USF81, was constructed. The expression of FadA on USF81 was confirmed by Western blotting and immunofluorescent labeling. USF81 restored host cell attachment and invasion activities. The ability of
F. nucleatum
12230, US1, and USF81 to colonize the mouse placenta was examined. US1 was severely defective in placental colonization compared to the wild type and USF81. Thus, FadA plays an important role in
F. nucleatum
colonization in vivo. These results also represent the first complementation studies for
F. nucleatum
. FadA may be a therapeutic target for preventing
F. nucleatum
colonization of the host.
Distinct Roles of CD28- and CD40 Ligand-Mediated Costimulation in the Development of Protective Immunity and Pathology duringChlamydia muridarumUrogenital Infection in Mice
Authors: Chen Lili , Cheng Wen , Shivshankar Pooja , Lei Lei , Zhang Xiaoyun , Wu Yimou , Yeh I-Tien , Zhong Guangming
Published: April 2009

Infection withChlamydia muridarumin the mouse urogenital tract can induce both protective immunity and inflammatory pathologies, which has been used as a model for understanding the immune and pathogenic mechanisms ofC. trachomatisinfection. We compared the roles of CD28- and CD40 ligand (CD40L)-mediated costimulation inC. muridaruminfection. Mice with CD28 or CD80/CD86 gene knockout (KO) displayed an infection course similar to that of wild-type mice during both primary and secondary infection, suggesting that CD28-mediated costimulation is not required for protection againstC. muridaruminfection. However, mice deficient in CD40L or CD40 displayed a prolonged infection course after primary or secondary infection, suggesting that CD40-CD40L costimulation plays an essential role in the development of anti-C. muridarumimmunity. Interestingly, the CD28- or CD80/CD86-deficient mice displayed significantly lower levels of inflammatory pathologies in the upper genital tracts after primary infection, although the attenuation in inflammation was no longer significant during secondary infection. However, the CD40L or CD40 KO mice developed inflammatory pathologies as severe as those in wild-type mice following either primary or secondary infection despite the obvious deficits in adaptive immunity in these KO mice. The resistance of CD28 or CD80/CD86 KO mice to chlamydial infection correlated with production of gamma interferon, while the development of inflammatory pathologies in CD40L or CD40 KO mice correlated with the production of other proinflammatory cytokines in mouse urogenital tracts during the early stages of the infection. These observations together suggest thatC. muridarum-induced protective immunity and inflammatory pathologies can be mediated by distinct costimulatory signals.
The Metal Homeostasis Protein, Lsp, of
Streptococcus pyogenes
Is Necessary for Acquisition of Zinc and Virulence
Authors: Weston Benjamin F. , Brenot Audrey , Caparon Michael G.
Published: April 2009

“Cluster 9” family lipoproteins function as ligand-binding subunits of ABC-type transporters in maintaining transition metal homeostasis and have been implicated in the virulence of several bacteria. While these proteins share high similarity, the specific metal that they recognize and whether their role in virulence directly involves metal homeostasis cannot be reliably predicted. We examined the cluster 9 protein Lsp of
Streptococcus pyogenes
and found that specific deletion of
lsp
produced mutants highly attenuated in a murine model of soft tissue infection. Under standard in vitro conditions, growth of the Lsp
−
mutant was indistinguishable from that of the wild type, but growth was defective under zinc-limited conditions. The growth defect could be complemented by plasmids expressing wild-type Lsp but not Lsp engineered to lack its putative lipidation residue. Furthermore, Zn
2+
but not Mn
2+
rescued Lsp
−
growth, implicating Zn
2+
as the physiological ligand for Lsp. Mutation of residues in the putative Zn
2+
-binding pocket generated variants both hypo- and hyperresistant to zinc starvation, and both mutant classes displayed attenuated virulence. Together, these data suggest that Lsp is a ligand-binding component of an ABC-type zinc permease and that perturbation of zinc homeostasis inhibits the ability of
S. pyogenes
to cause disease in a zinc-limited host milieu.
Listeria monocytogenes
6-Phosphogluconolactonase Mutants Induce Increased Activation of a Host Cytosolic Surveillance Pathway
Authors: Crimmins Gregory T. , Schelle Michael W. , Herskovits Anat A. , Ni Peggy P. , Kline Benjamin C. , Meyer-Morse Nicole , Iavarone Anthony T. , Portnoy Daniel A.
Published: April 2009

Infection with wild-type
Listeria monocytogenes
activates a host cytosolic surveillance response characterized by the expression of beta interferon (IFN-β). We performed a genetic screen to identify
L. monocytogenes
transposon insertion mutants that induced altered levels of host IFN-β expression. One mutant from this screen induced elevated levels of IFN-β and harbored a Tn
917
insertion upstream of lmo0558. This study identified lmo0558 as the 6-phosphogluconolactonase gene (
pgl
), which encodes the second enzyme in the pentose phosphate pathway.
pgl
mutant
L. monocytogenes
accumulated and secreted large amounts of gluconate, likely derived from labile 6-phosphogluconolactone, the substrate of Pgl. The
pgl
deletion mutant had decreased growth in glucose-limiting minimal medium but grew normally when excess glucose was added. Microarray analysis revealed that the
pgl
deletion mutant had increased expression of several β-glucosidases, consistent with known inhibition of β-glucosidases by 6-phosphogluconolactone. While growth in macrophages was indistinguishable from that of wild-type bacteria,
pgl
mutant
L. monocytogenes
exhibited a 15- to 30-fold defect in growth in vivo. In addition,
L. monocytogenes
harboring an in-frame deletion of
pgl
was more sensitive to oxidative stress. This study identified
L. monocytogenes pgl
and provided the first link between the bacterial pentose phosphate pathway and activation of host IFN-β expression.
Predicting site-specific overwintering of juvenile brown trout (Salmo trutta) using a habitat suitability index
Authors: Palm Daniel , Brännäs Eva , Nilsson Kjell
Published: April 2009

Brown trout ( Salmo trutta ) site-specific overwintering was studied in an ice-covered stream in northern Sweden. We monitored 238 individually tagged juvenile trout (body length 120–204 mm) from late summer until late winter using portable passive integrated transponder tag equipment and related it to a habitat suitability index. Minimum habitat suitability index explained a large portion (66.8%) of the variation in the proportion of individuals that remained and overwintered at specific sites from late summer until late winter. Our study design detected three scales of overwinter movements: (i) individuals that remained within their tagging site (site-scale movements); (ii) individuals that moved to other reaches (reach-scale movements), which were probably the most common; and (iii) individuals that left the study stream (stream-scale movements). There were no differences in size at tagging among individuals that adopted different scales of movements. We suggest that habitat suitability index can be used as a tool to predict site specific residency and, thus, habitat conditions in stream reaches during winter.
High niche overlap between two successfully coexisting pairs of Lake Malawi cichlid fishes
Authors: Martin Christopher H. , Genner Martin J.
Published: April 2009

Many species in high-diversity assemblages appear to coexist in similar ecological niches. It has been proposed that interspecific resource partitioning in these assemblages may only occur during periods of resource scarcity. We tested this hypothesis by measuring resource abundance, dietary overlap, foraging rate, and territoriality in a Lake Malawi rock cichlid assemblage over a period of 1 year. Our study examined two pairs of morphologically similar species, with each pair comprising one native species and one invader species that has successfully established after being translocated from another region of the lake. All four species changed their diet and foraging rate in response to seasonal variation in resource abundance. However, dietary overlap within both species pairs remained high in all seasons and was not influenced by resource availability. Similarly, territoriality did not decline during periods of low resource availability, suggesting no decrease in the strength of interspecific competition. These data suggest that these species pairs are successfully coexisting despite substantial niche overlap during resource scarcity. Thus, the coexistence of species within this radiation may not depend on the evolution of divergent resource use patterns.
Natural variation of profundal macroinvertebrate communities in boreal lakes is related to lake morphometry: implications for bioassessment
Authors: Jyväsjärvi Jussi , Tolonen Kimmo T. , Hämäläinen Heikki
Published: April 2009

Modern biological assessment of aquatic systems is often based on the reference condition approach, which requires characterization of biota in undisturbed conditions. For this approach, it is essential to recognize the origins and degree of natural variation in communities. We used data from 55 minimally disturbed Finnish lake basins to investigate the natural variation of profundal macroinvertebrate community composition in relation to environmental factors. Partial canonical correspondence analysis showed that most (68% combined, 39% uniquely) of the total explained compositional variation (29%) was correlated with environmental variables insensitive to human activities, especially lake morphometry. In contrast, the unique contributions of geographical location and variables influenced by human activities (dissolved oxygen and total phosphorus) were substantially smaller (5.5% and 22%, respectively). All of the explained variation (38%–64%) of three widely used community metrics was also correlated with human-insensitive environmental factors. The results suggest that variation in undisturbed profundal invertebrate communities of reference sites is strongly dependent on variables insensitive to human activities and especially on those related to lake morphometry, suggesting that reference communities for bioassessment of impacted lakes should be rather predictable from these variables.
A generic model to estimate food consumption: linking von Bertalanffy’s growth model with Beverton and Holt’s and Ivlev’s concepts of net conversion efficiency
Authors: Temming Axel , Herrmann Jens P.
Published: April 2009

In this paper, a mathematical derivation is presented that links von Bertalanffy’s growth model with the concept of net conversion efficiency of Beverton and Holt, aiming at the development of an equation that can calculate food consumption rates of wild populations from parameters of the von Bertalanffy growth equation and an estimate of the net food conversion efficiency of Beverton and Holt. The derivation is based on Pauly’s version of the generalized von Bertalanffy equation, which allows the allometric exponent of the anabolism term to differ from 2/3, as in the standard von Bertalanffy equation. As a side product, a general model is formulated that describes the gross growth conversion efficiency (K1 of Ivlev) as a function of weight of the organism. The new equations for the estimation of food consumption are applied in two case studies, North Sea cod ( Gadus morhua ) and whiting ( Merlangius merlangus ), for which a variety of consumption estimates is available from conventional gastric evacuation-based methods. The new method produces results that show a similar degree of variability as was observed in various applications of the gastric evacuation method.
The effect of on-ramp and off-ramp on the one dimensional road with open boundaries
Authors: Mhirech Abdelaziz , Ismaili Assia Alaoui , Ez-Zahraouy Hamid
Published: April 2009

The effect of one on-ramp (entry) and one off-ramp (exit) is investigated numerically in a one dimensional cellular automaton traffic flow model, with open boundary conditions, using parallel dynamics. Our aim in this paper is to study how the injection rates α and α0 and the extraction rates β and β0 act on the density and flux of cars in a one dimensional road. The priority of occupation at entry site i1 (removing at exit site i2) is attributed to the particle that entered (was absorbed) the chain. Phase diagrams in (β0, α0) and (β, α0) plans are established. For α = 0.1, they show three different topologies in the flow behaviour. The first one corresponds to the presence of four regions, by varying α0, namely low-density phase (LDP), intermediate-density phase (IDP), plateau current phase (PCP), and high-density phase (HDP). In the second topology, the intermediate-density phase disappears. The third topology presents only two regions, i.e., low- and high-density phases. For small values of α, the (IDP) and (PCP) disappear, respectively, by increasing β. When increasing α, the fourth topology, corresponding to one phase (HDP), appears for low values of β and β0.
Deformation due to various sources in a fibre-reinforced anisotropic generalized thermoelastic medium
Authors: Kumar Rajneesh , Gupta Raj Rani
Published: April 2009

The present investigation is concerned with the deformation of a fibre-reinforced, anisotropic, generalized thermoelastic medium subjected to mechanical and thermal sources acting on the plane surface. Close-form solutions for stresses and temperature distribution are derived using Laplace transforms for time and Fourier transforms for space. As an application of the approach concentrated, uniformly distributed, and linearly distributed sources are taken. A numerical inversion technique is applied to obtain the solution in the physical domain. Effects of anisotropy and thermal relaxation are shown graphically on the resulting quantities.
Repeated compressive loading of Leda clay
Authors: Raymond G. P. , Gaskin P. N. , Addo-Abedi F. Y.
Published: April 2009

Repeated load drained tests on Leda clay, as related to subgrade performance, are reported. A threshold stress divided the performance into failing and stable specimens. For the stable specimens the resilient modulus attained equilibrium at about 105 cycles but varied with stress level. Permanent strains continued even at low stresses.
Triaxial-vane tests on a soft marine clay
Authors: Law K. Tim
Published: April 2009

This paper describes a triaxial-vane apparatus constructed at the Division of Building Research, National Research Council of Canada, Ottawa. A series of tests was conducted on a soft marine clay from South Gloucester, Ontario. Various consolidation pressures were used to study the effect of pressure on vane strength. The test results show that the vane strength is relatively insensitive to a change in vertical consolidation pressure only, but increases steadily with increase in the all-around or horizontal consolidation pressure. This phenomenon is explained using an analysis that incorporates strength anisotropy. The practical implications resulting from this study are also discussed.
The loading behaviour of initially bent large scale laboratory piles in sand
Authors: Chan S. F. , Hanna T. H.
Published: April 2009

Field measurements indicate that piles are sometimes bent during driving. This paper reports on the results of an experimental study, at laboratory scale, of the behaviour of bent single piles when subjected to vertical loads. Varying degrees of bend were adopted for both friction and end bearing piles. The test piles, which were embedded in a cohesionless soil, were instrumented to measure the distributions of axial load, bending moment, and transverse shear along the pile shaft.The behaviour of bent piles was found to be far more complex than that of straight piles. For both the friction and end bearing piles, the response of the piles was governed by the degree of bend and the magnitudes of the moments and shears were significant at all levels of the applied load. An important feature in the pile response was the large residual moments and shears locked in the pile on unloading. The implications of the observed pile behaviour in relation to practice are discussed. A review of the reported cases of pile bending is also presented.
Creep of model piles in frozen soil
Authors: Parameswaran V. R.
Published: April 2009

Preliminary results of laboratory studies on the behaviour of model piles of wood, concrete, and steel, having different surface finishes, embedded in artificially frozen sand and subject to constant loads, are reported in this paper. The displacement rate [Formula: see text], was found to vary with the applied stress [Formula: see text]f, according to a steady state creep equation of the type [Formula: see text], as found for other viscoelastic materials such as metals at high temperature. The value of the exponent n varied between 6.7 and 9.1 for various types of piles.The results agreed favourably with field data obtained from pile pull-out tests carried out at Gillam and Thompson, Manitoba. The value of n from Gillam and Thompson tests, 8.05 and 7.5, respectively, were within the range of the present experimental values. Comparison with pile pull-out tests carried out in ice, and theoretical predictions for ice showed that the value of the exponent n was much larger for frozen soil than for ice. The bearing capacity at a particular displacement rate was also found to be almost an order of magnitude larger in frozen soil than in ice.
Second Canadian Geotechnical Colloquium: Appropriate concepts and technology for unsaturated soils
Authors: Fredlund D. G.
Published: April 2009

A practical science has not been fully developed for unsaturated soils for two main reasons. First, there has been the lack of an appropriate science with a theoretical base. Second, there has been the lack of an appropriate technology to render engineering practice financially viable.This paper presents concepts that can be used to develop an appropriate engineering practice for unsaturated soils. The nature of an unsaturated soil is first described along with the accompanying stress conditions. The basic equations related to mechanical properties are then proposed. These are applied to practical problems such as earth pressure, limiting equilibrium, and volume change.An attempt is made to demonstrate the manner in which saturated soil mechanics must be extended when a soil is unsaturated. Two variables are required to describe the stress state of an unsaturated soil (e.g., (σ – ua) and (ua – uW). There is a smooth transition from the unsaturated case to the saturated case since the pore-air pressure becomes equal to the pore-water pressure as the degree of saturation approaches 100%. Therefore, the matrix suction (i.e., (ua – uW) goes to 0 and the pore-water pressure can be substituted for the pore-air pressure (i.e., (σ – uW)).The complete volumetric deformation of an unsaturated soil requires two three-dimensional constitutive surfaces. These converge to one two-dimensional relationship for a saturated soil. The shear strength for an unsaturated soil is a three-dimensional surface that reduces to the conventional Mohr–Coulomb envelope for a saturated soil.The manner of applying the volumetric deformation equations and the shear strength equation to practical problems is demonstrated. For earth pressure and limiting equilibrium problems, the unsaturated soil can be viewed as a saturated soil with an increased cohesion. The increase in cohesion is proportional to the matrix suction of the soil. For volume change problems it is necessary to have an indication of the relationship between the various soil moduli.There is a need for further experimental studies and case histories to substantiate the proposed concepts and theories.
Stability of swelling clay embankments
Authors: Widger R. A. , Fredlund D. G.
Published: April 2009

A common occurrence in cuts or fills of swelling soils is their reduction in strength with time. At the time of compaction, the clay generally has a high matrix suction. Correspondingly, it has a high strength and will stand at relatively steep side slopes. With time, the soil generally tends towards saturation and the matrix suction reduces towards zero. There is a reduction in total strength and if the gravitational forces are too large, the slope fails.During the past several years, numerous cut and fill slopes have been observed in the Regina area of Saskatchewan. Many of these slopes have remained stable for 4–6 years and then failed. There has been a 20 year history of observations on the Belle Plaine overpass west of Regina. Field and laboratory investigations have been conducted.With a knowledge of the geometry of the slope and failure plane, the simplified Bishop method of stability analysis was used to perform a 'back-analysis' to assess the shear strength parameters. The shear strength parameters from the laboratory program are compared with those calculated from the stability analyses. The analyses indicate that the peak shear strength parameters from triaxial tests on the softened Regina clay (i.e., c' = 5 kPa and [Formula: see text]), with the appropriate pore water pressures, give a factor of safety of 1 for the failed surface. The effect of spring thawing appears to be to produce the condition of most serious pore water pressures.