bluuebunny/crossref_metadata_2025 huggingface dataset:
Active RFID for Enhanced Railway Operations
Authors: Amanna Ashwin , Agrawal Ambuj , Manteghi Majid
Published: April 2011

RFID tags have been used by railways for many years, RFID has proven its worth in inventory management, yet this technology is underutilized for enhancing railway operations and health monitoring due to limitations of passive RFID technology. Active RFID provides enhanced capabilities with potential to improve railway operations. Active technology differs from passive RFID by incorporating an onboard power source enabling longer ranges, changeable data fields, and the ability to transmit independently of the reader. This paper compares the advantages and disadvantages of active compared to passive RFID in terms of power requirements, transmission range, and dynamic data. A survey of existing products and vendors is presented. The existing active RFID standards are reviewed and elements of the data tag protocols are detailed as well as protocols for mitigating collisions of data packets. Finally, specific railway applications utilizing active RFID are discussed.
Characteristics of Eddy Current Braking
Authors: Berger Karl W.
Published: April 2011

Eddy current braking has long held the promise of frictionless braking of railroad trains. The advantages of eliminating friction brake equipment are particularly valuable to high speed rail passenger service. Tests over the last decade have identified a number of controllable challenges to implementing eddy current brakes involving the vehicle, track, and wayside equipment. High speed trains equipped with eddy current brakes are in service in Europe and under consideration worldwide. This paper illustrates the fundamental characteristics of eddy current braking, locates the technology with respect to other braking systems technologies, and highlights wayside compatibility issues involved in deploying high speed trains with eddy current braking.
Phoenix Light Rail Vehicle Front End Design Review With Crash Energy Management Bumper
Authors: Donohue Brian P.
Published: April 2011

December 27, 2008 marked the grand opening of METRO Light Rail transit service linking the cities of Phoenix, Tempe and Mesa, Arizona. In Phoenix, this event harkened back to an era with similar streetcar service that ceased operations in 1948. After a 55 year absence, final design of the modern system commenced in 2003, and the acute need to address safety concerns with a new generation of valley residents began. This 20.4 mile (32.6 km) system contains 28 stations, runs on reserved rights of way, >95% in city streets, and contains over 149 street traffic intersections, highway ramps and slip-ramps. In an effort to lessen injuries and damage to the public, train crew and light rail equipment, the Agency’s consultant recommended several key changes to the typical North American light rail system design. Included was an unprecedented change to the front end of the light rail vehicles with an industry first, crash energy management (CEM) bumper. This report discusses the design and functionality of the Phoenix LRV front end and bumper from concept through revenue service.
Mathematical Simulation of Air Suspension Failure and Derailment
Authors: Schreiber Patricia , Wilson Nicholas
Published: April 2011

Air suspensions are a commonly used component of modern transit and passenger vehicle suspensions. New vehicle performance specifications usually require testing and analyses with the air suspension inflated and also deflated. However, the tests and analyses usually do not include the dynamic effects that may occur at the instant of deflation. Transportation Technology Center, Inc. (TTCI) recently investigated a revenue service flange climb derailment for a large North American transit system. The derailment occurred on the diverging route of a No. 10 turnout. Initial investigation by the transit system did not identify any track or equipment that showed significant deviations from their normal practices; no obvious cause for the derailment was identified, although the air suspension had been deflated after the derailment. To assist in determining potential contributing factors for the derailment, TTCI conducted NUCARS® simulations of the car negotiating the turnout, using these parameters: • Vehicle dynamic response to local track geometry conditions, including motions of the air suspension; • Sudden deflation of the air suspension; • Wheel and rail profiles. This paper presents the methods used to represent sudden component failures in the NUCARS simulations, including the air suspension deflation. The simulation results show how the sudden deflation of the air suspension combined with local track geometry and wheel/rail contact conditions could contribute to a flange climb derailment.
Advanced Devices for Safer Freight Train Switching Operations
Authors: Vithani Anand R. , Brabb David C. , Martin Kenneth L. , Kandoth-Kannoth Harish , Stewart Monique F. , Punwani S. K.
Published: April 2011

Freight train switching operations involve significant manual operations creating a safety hazard for the train crew and resulting in numerous injuries and fatalities every year. There is a need to develop, test, and deploy advanced devices that enable automation and improve the safety and efficiency of freight train switching operations. With that goal in mind, the Federal Railroad Administration has funded multiple projects aimed at developing these advanced devices. This paper presents three advanced devices — Remote Controlled Cut Lever, Remote Controlled Angle Cock, and Hand Brake Release Sensor — that will bring the industry one step closer to safer, more efficient and automated freight train switching operations. These devices were tested extensively in a laboratory and in a rail-yard environment and work is under way for testing these devices in a mainline operation.
CD44-SLC1A2
Gene Fusions in Gastric Cancer
Authors: Tao Jiong , Deng Nian Tao , Ramnarayanan Kalpana , Huang Baohua , Oh Hue Kian , Leong Siew Hong , Lim Seong Soo , Tan Iain Beehuat , Ooi Chia Huey , Wu Jeanie , Lee Minghui , Zhang Shenli , Rha Sun Young , Chung Hyun Cheol , Smoot Duane T. , Ashktorab Hassan , Kon Oi Lian , Cacheux Valere , Yap Celestial , Palanisamy Nallasivam , Tan Patrick
Published: April 2011

One partner of a fusion gene found in gastric cancer,
CD44-SLC1A2
, may contribute to the tumor’s abnormal metabolism.
Genital HIV-1 RNA Predicts Risk of Heterosexual HIV-1 Transmission
Authors: Baeten Jared M. , Kahle Erin , Lingappa Jairam R. , Coombs Robert W. , Delany-Moretlwe Sinead , Nakku-Joloba Edith , Mugo Nelly R. , Wald Anna , Corey Lawrence , Donnell Deborah , Campbell Mary S. , Mullins James I. , Celum Connie
Published: April 2011

Genital HIV-1 RNA quantity predicts risk of heterosexual HIV-1 transmission independently of plasma HIV-1 concentration.
Enemies Among Us
Authors: Nyendak Melissa
Published: April 2011

Invasive streptococcal strains are genetically similar to pharyngitis strains, yet polymorphisms lead to changes in invasive potential.
trans-Sialidase Neutralizing Antibody Detection in Trypanosoma cruzi-Infected Domestic Reservoirs
Authors: Sartor Paula A. , Cardinal Martha V. , Orozco Marcela M. , Gürtler Ricardo E. , Leguizamón M. Susana
Published: April 2011

The detection ofTrypanosoma cruziinfection in domestic dogs and cats is relevant to evaluating human transmission risks and the effectiveness of insecticide spraying campaigns. However, the serological assays routinely used are associated with cross-reactivity in sera from mammals infected withLeishmaniaspp. We used atrans-sialidase inhibition assay (TIA) forT. cruzidiagnosis in serum samples from 199 dogs and 57 cats from areas where these types of infections are endemic. TIA is based on the antibody neutralization of recombinanttrans-sialidase, an enzyme that is not detected in the coendemicLeishmaniaspecies orTrypanosoma rangeliparasites.T. cruziinfection was also evaluated by conventional serology (CS) (indirect immunofluorescence, indirect hemagglutination, enzyme-linked immunosorbent assay, and immunochromatographic dipstick test) and xenodiagnosis. Sera from 30 dogs and 15 cats from areas where these organisms are not endemic and 5 dogs with visceral leishmaniasis were found to be nonreactive by TIA and CS. Samples from dogs and cats demonstrated 91 and 95% copositivities between TIA and CS, whereas the conegativities were 98 and 97%, respectively. Sera from xenodiagnosis-positive dogs and cats also reacted by TIA (copositivities of 97 and 83%, respectively). TIA was reactive in three CS-negative samples and was able to resolve results in two cat serum samples that were CS inconclusive. Our study is the first to describe the development oftrans-sialidase neutralizing antibodies in naturally infected dogs and cats. High CS conegativity and the absence oftrans-sialidase neutralization in dog sera from areas where leishmaniasis is not endemic and from dogs with visceral leishmaniasis support TIA specificity. The TIA may be a useful tool forT. cruzidetection in the main domestic reservoirs.
Novel Electrical Method for Early Detection of Viable Bacteria in Blood Cultures
Authors: Puttaswamy Sachidevi , Lee Byung Doo , Sengupta Shramik
Published: April 2011

We present a novel electrical method for detecting viable bacteria in blood cultures that is 4 to 10 times faster than continuous monitoring blood culture systems (CMBCS) like the Bactec system. Proliferating bacteria are detected via an increase in the bulk capacitance of suspensions, and the threshold concentration for detection is ∼10
4
CFU/ml (compared to ∼10
8
CFU/ml for the Bactec system).
Phenotypic, Genotypic, and Antibiotic Sensitivity Patterns of Strains Isolated from the Cholera Epidemic in Zimbabwe
Authors: Islam Mohammad S. , Mahmud Zahid H. , Ansaruzzaman Mohammad , Faruque Shah M. , Talukder Kaisar A. , Qadri Firdausi , Alam Munirul , Islam Shafiqul , Bardhan Pradip K. , Mazumder Ramendra N. , Khan Azharul I. , Ahmed Sirajuddin , Iqbal Anwarul , Chitsatso Owen , Mudzori James , Patel Sheetal , Midzi Stanley M. , Charimari Lincoln , Endtz Hubert P. , Cravioto Alejandro
Published: April 2011

This paper details the phenotypic, genotypic, and antibiotic sensitivity patterns of 88
Vibrio cholerae
strains from Zimbabwe. Of the 88 strains, 83 were classified as “altered El Tor” and 5 as “hybrid El Tor” strains. All of the strains were susceptible to tetracycline, doxycycline, ciprofloxacin, and azithromycin by disc diffusion, but susceptibility to tetracycline and azithromycin diminished when observed using the MIC method.
Point-Counterpoint: Should Interferon Gamma Release Assays Become the Standard Method for Screening Patients for Mycobacterium tuberculosis Infections in the United States?
Authors: Alexander Thomas S. , Miller Melissa B. , Gilligan Peter
Published: April 2011

The Centers for Disease Control and Prevention recently published updated guidelines for the use of interferon gamma release assays (IGRAs) to detect
Mycobacterium tuberculosis
. This document gives a balanced analysis of the strengths and weaknesses of IGRAs. To date, these assays have not been widely adopted in the United States by clinical laboratories. We have asked two experts, Thomas Alexander of Summa Health Care, who has adopted an IGRA for
M. tuberculosis
detection in his laboratory, and Melissa Miller of UNC Hospitals, who has evaluated one but has not chosen to adopt it, to explain how each reached this decision based on their experience with the test and the data that have been published concerning IGRA.
Characterization of Cases of Clostridium difficile Infection (CDI) Presenting at an Emergency Room: Molecular and Clinical Features Differentiate Community-Onset Hospital-Associated and Community-Associated CDI in a Tertiary Care Hospital
Authors: Shin Bo-Moon , Moon Se Jin , Kim You Sun , Shin Won Chang , Yoo Hyeon Mi
Published: April 2011

Definition of community-onset, hospital-acquired
Clostridium difficile
infection (CO-HA-CDI) is difficult in patients presenting with diarrhea at hospitals or outpatient clinics, especially 4 to 12 weeks after the last discharge. We performed
C. difficile
stool culture for 272 diarrheic patients visiting the emergency room (ER) between January 2006 and June 2010.
C. difficile
was isolated from 36 cases (13.2%), and isolation rates increased year by year, from 10.1% in 2008 to 12.4% in 2009 and 16.7% in 2010. Among 32 toxin-positive isolates, 13 (40.6%) and 19 (59.4%) were associated with CO-HA-CDI and community-acquired CDI (CA-CDI), respectively, if cases with CDI diagnosed within 12 weeks after discharge were considered hospital associated. The majority (70%) of CO-HA-CDI cases occurred within 2 weeks after hospital discharge, although the interval from discharge to onset of symptoms was as long as 10 weeks. We found via
tcdA
and
tcdB
and repetitive sequence PCR analysis, that toxin A-positive/toxin B-positive isolates were the most prevalent in both CO-HA-CDI (53.8%) and CA-CDI (94.7%) cases. Toxin A-negative/toxin B-positive isolates were also still highly associated with HA-CDI cases but were also observed in CA-CDI cases. Younger age, fewer underlying diseases, lack of prior antibiotic use, and genetic diversity of isolates in repetitive sequence PCR were the main characteristics in CA-CDI cases visiting the ER.
Comparison of Real-Time PCR Assays for Detection of Pathogenic Leptospira spp. in Blood and Identification of Variations in Target Sequences
Authors: Bourhy Pascale , Bremont Sylvie , Zinini Farida , Giry Claude , Picardeau Mathieu
Published: April 2011

Leptospirosis is considered an underdiagnosed disease. Although several PCR-based methods are currently in use, there is little information on their comparability. In this study, four quantitative real-time PCR (qPCR) assays (SYBR green and TaqMan chemistries) targeting the
secY
,
lfb1
, and
lipL32
genes were evaluated as diagnostic assays. In our hands, these assays can detect between 10
2
and 10
3
bacteria/ml of pure culture, whole-blood, plasma, and serum samples. In three independent experiments, we found a slightly higher sensitivity of the PCR assays in plasma than in whole blood and serum. We also evaluated the specificity of the PCR assays on reference
Leptospira
strains, including newly described
Leptospira
species, and clinical isolates. No amplification was detected for DNA obtained from saprophytic or intermediate
Leptospira
species. However, among the pathogens, we identified sequence polymorphisms in target genes that result in primer and probe mismatches and affect qPCR assay performance. In conclusion, most of these assays are sensitive and specific tools for routine diagnosis of leptospirosis. However, it is important to continually evaluate and, if necessary, modify the primers and/or probes used to ensure effective detection of the circulating
Leptospira
isolates.
Electron Tomography Reveals Polyhedrin Binding and Existence of both Empty and Full Cytoplasmic Polyhedrosis Virus Particles inside Infectious Polyhedra
Authors: Chen Justin , Sun Jingchen , Atanasov Ivo , Ryazantsev Sergey , Zhou Z. Hong
Published: April 2011

Previous studies have described the structure of purified cytoplasmic polyhedrosis virus (CPV) and that of polyhedrin protein. However, how polyhedrin molecules embed CPV particles inside infectious polyhedra is not known. By using electron tomography, we show that CPV particles are occluded within the polyhedrin crystalline lattice with a random spatial distribution and interact with the polyhedrin protein through the A-spike rather than as previously thought through the B-spike. Furthermore, both full (with RNA) and empty (no RNA) capsids were found inside polyhedra, suggesting a spontaneous RNA encapsidating process for CPV assembly
in vivo
.
Oncolytic Specificity of Newcastle Disease Virus Is Mediated by Selectivity for Apoptosis-Resistant Cells
Authors: Mansour Mena , Palese Peter , Zamarin Dmitriy
Published: April 2011

Newcastle disease virus (NDV) is a negative-sense RNA virus that has been shown to possess oncolytic activity. NDV's selective replication in tumor cells has been previously suggested to be due to the lack of a proper antiviral response in these cells. Here we demonstrate that NDV possesses oncolytic activity in tumor cells capable of a robust type I interferon (IFN) response, suggesting that another mechanism underlies NDV's tumor specificity. We show that the oncolytic selectivity of NDV for tumor cells is dependent upon tumor cell resistance to apoptosis. Utilizing the human non-small-cell lung cancer cell line A549 overexpressing the antiapoptotic protein Bcl-xL, we show significant enhancement of oncolytic activity and NDV replication. Interestingly, while the Bcl-xL-overexpressing cells were resistant to apoptotic stimuli induced by chemotherapeutic agents and early viral replication, during the subsequent viral cycles, we observed a paradoxical increase in apoptosis in response to NDV. The increased oncolytic activity seen was secondary to enhanced viral replication and syncytium formation. The induction of a type I IFN response was enhanced in Bcl-xL cells. Overall, these findings propose a new mechanism for cancer cell specificity for NDV, making it an attractive anticancer agent for chemoresistant tumors with enhanced antiapoptotic activity.
Coxsackievirus Preferentially Replicates and Induces Cytopathic Effects in Undifferentiated Neural Progenitor Cells
Authors: Tsueng Ginger , Tabor-Godwin Jenna M. , Gopal Aparajita , Ruller Chelsea M. , Deline Steven , An Naili , Frausto Ricardo F. , Milner Richard , Crocker Stephen J. , Whitton J. Lindsay , Feuer Ralph
Published: April 2011

Enteroviruses, including coxsackieviruses, exhibit significant tropism for the central nervous system, and these viruses are commonly associated with viral meningitis and encephalitis. Previously, we described the ability of coxsackievirus B3 (CVB3) to infect proliferating neuronal progenitor cells located in the neonatal subventricular zone and persist in the adult murine central nervous system (CNS). Here, we demonstrate that cultured murine neurospheres, which comprise neural stem cells and their progeny at different stages of development, were highly susceptible to CVB3 infection. Neurospheres, or neural progenitor and stem cells (NPSCs), isolated from neonatal C57BL/6 mice, supported high levels of infectious virus production and high viral protein expression levels following infection with a recombinant CVB3 expressing enhanced green fluorescent protein (eGFP) protein. Similarly, NPSCs isolated from neonatal actin-promoter-GFP transgenic mice (actin-GFP NPSCs) were highly susceptible to infection with a recombinant CVB3 expressing DsRed (Discosomasp. red fluorescent protein). Both nestin-positive and NG2+progenitor cells within neurospheres were shown to preferentially express high levels of viral protein as soon as 24 h postinfection (p.i.). By day 3 p.i., viral protein expression and viral titers increased dramatically in NPSCs with resultant cytopathic effects (CPE) and eventual cell death. In contrast, reduced viral replication, lower levels of CPE, and diminished viral protein expression levels were observed in NPSCs differentiated for 5 or 16 days in the presence of fetal bovine serum (FBS). Despite the presence of CPE and high levels of cell death following early CVB3 infection, surviving neurospheres were readily observed and continued to express detectable levels of viral protein as long as 37 days after initial infection. Also, CVB3 infection of actin-GFP NPSCs increased the percentage of cells expressing neuronal class III β-tubulin following their differentiation in the presence of FBS. These results suggest that neural stem cells may be preferentially targeted by CVB3 and that neurogenic regions of the CNS may support persistent viral replication in the surviving host. In addition, normal progenitor cell differentiation may be altered in the host following infection.
Virus-Induced Transient Immune Suppression and the Inhibition of T Cell Proliferation by Type I Interferon
Authors: Marshall Heather D. , Urban Stina L. , Welsh Raymond M.
Published: April 2011

Vaccine-induced memory is necessary for protective immunity to pathogens, but many viruses induce a state of transient immune suppression that might contribute to the inability of a vaccine to elicit immunity. We evaluated here the fate of bystander T cells activated by third party cognate antigens during acute viral infectionsin vivo, using distinct models to track and specifically activate HY and P14 transgenic bystander CD8 T cellsin vivoduring acute arenavirus infections of mice. Viral infections acted as stimulatory adjuvants when bystander T cells were exposed to an inflammatory milieu and cognate antigens at the beginning of infections, but bystander CD8 T cell proliferation in response to cognate antigen was inhibited 3 to 9 days after virus infection. Reduced proliferation was not dependent on Fas-FasL- or tumor necrosis factor (TNF)-induced activation-induced cell death or on deficiencies of antigen presentation. Instead, reduced proliferation was associated with a delayed onset of division that was an intrinsic defect of T cells. Inhibition of proliferation could be simulated by exposure of T cells to the Toll-like receptor agonist and type I interferon (IFN) inducer poly(I · C). T cells lacking IFN-α/β receptors resisted both the suppressive effects of preexposure to poly(I · C) and the stimulatory effects of type I IFN, indicating that the timing of exposure to IFN can have negative or positive effects on T cell proliferation. Inhibition of T cell receptor-stimulated bystander CD8 T cell proliferation during acute viral infections may reflect the reduced ability of vaccines to elicit protective immunity when administered during an acute illness.
Receptor-Ligand Requirements for Increased NK Cell Polyfunctional Potential in Slow Progressors Infected with HIV-1 Coexpressing KIR3DL1*h/*y and HLA-B*57
Authors: Kamya Philomena , Boulet Salix , Tsoukas Christos M. , Routy Jean-Pierre , Thomas Réjean , Côté Pierre , Boulassel Mohamed-Rachid , Baril Jean-Guy , Kovacs Colin , Migueles Stephen A. , Connors Mark , Suscovich Todd J. , Brander Christian , Tremblay Cecile L. , Bernard Nicole ,   for the Canadian Cohort of HIV Infected Slow Progressors
Published: April 2011

Carriage of the natural killer (NK) receptor genotype KIR3DL1*h/*y with its HLA-B*57 ligand (*h/*y+B*57) is associated with slow time to AIDS and low viral load (VL). To provide a functional basis for these epidemiological observations, we assessed whether HIV-1-infected slow progressors (SP) carrying the *h/*y+B*57 compound genotype would have increased NK cell polyfunctional potential in comparison to SP with other killer immunoglobulin-like receptor (KIR)/HLA compound genotypes and whether this enhanced polyfunctionality was dependent upon the coexpression of both KIR3DL1*h/*y and HLA-B*57. The functional potential of NK cells was investigated by stimulating peripheral blood mononuclear cells with HLA-devoid targets or single HLA transfectants. Multiparametric flow cytometry was used to detect NK cells with seven functional profiles representing all permutations of CD107a expression and gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) secretion. NK cells from individuals carrying KIR3DL1 receptor–HLA-Bw4 ligand pairs had greater trifunctional responses than those from KIR3DL1 homozygotes (hmz), who were Bw6 homozygotes. NK cells from subjects carrying the *h/*y+B*57 genotypes exhibited the highest trifunctional potential, and this was dependent on cocarriage of the NK receptor and its ligand. Trifunctional cells secreted more of each function tested on a per-cell basis than each corresponding monofunctional NK subset. Although VL influenced NK functionality, individuals with defined KIR/HLA genotypes exhibited differences in NK cell polyfunctionality that could not be accounted for by VL alone. The protective effect of HLA-B*57 on slow progression to AIDS and low VL may be mediated through its interaction with KIR3DL1 alleles to educate NK cells for potent activity upon stimulation.
Two uncertainty relations
Authors: Skála Lubomír , Kapsa Vojtěch
Published: April 2011

Heisenberg and Robertson–Schrödinger uncertainty relations for the coordinate and momentum follow from two stronger uncertainty relations. The first uncertainty relation has classical character and its right-hand side can have an arbitrary value greater than or equal to zero. The second uncertainty relation has quantum character and its right-hand side equals h2/4; its existence is related to the existence of the envelop of the wave function. These two uncertainty relations cannot be obviously improved on. The equality sign in the second relation can be achieved for much larger class of the wave functions than in case of the Heisenberg or Robertson–Schrödinger uncertainty relations.
Enantioselective epoxide ring opening catalyzed by bis(tetrahydroisoquinoline) N,N′-dioxides
Authors: Kadlčíková Aneta , Vlašaná Klára , Kotora Martin
Published: April 2011

Four bis(tetrahydroisoquinoline) N,N′-dioxides were used as catalysts for the epoxide ring opening with tetrachlorosilane under various conditions. A strong solvent effect on asymmetric induction was observed for each of the used catalysts. The highest achieved asymmetric induction for the opening of meso-stilbene oxide was 69% ee. Regarding the cycloalkene oxides, 56% ee was obtained in the reaction with cyclooctene oxide.
Evaluating the safety and effectiveness of percutaneous acetabuloplasty
Authors: Gupta Amar C , Hirsch Joshua A , Chaudhry Zeshan A , Chandra Ronil V , Pulli Benjamin , Galinsky Janice G , Hirsch Ariel E , Yoo Albert J
Published: April 2011

Purpose

To evaluate the safety and effectiveness of percutaneous acetabuloplasty in treating the pain and disability related to metastatic lesions of the acetabulum.

Materials and methods

This institutional review board approved retrospective study examined 11 patients who underwent percutaneous acetabuloplasty in our hospital from April 2007 to June 2010. All patients gave informed consent prior to the procedure, and all records were HIPAA compliant. Chart review was performed to collect patient demographics and to assess pre- and post-treatment patient performance on the Visual Analog Scale, Functional Mobility Scale and Analgesic Scale. Paired testing comparing the pre- and post-treatment scores for each patient was performed using the Wilcoxon signed rank test.

Results

There were 11 procedures: 10 performed under CT guidance and one using fluoroscopic guidance. There was a statistically significant decrease in patient Visual Analog Scale score (p=0.001) and Functional Mobility Scale score (p=0.03) after treatment. There was no change in median Analgesic Scale scores pre- and post-treatment although paired testing revealed a trend towards reduced analgesic use postoperatively (p=0.06). There were no clinically significant complications in this series.

Conclusion

Percutaneous acetabuloplasty appears to be safe and effective for improving the pain and decreased mobility secondary to metastatic lesions of the acetabulum.
Tolerance of ectomycorrhizal fungus mycelium to low temperature and freezing–thawing
Authors: Ma Dalong , Yang Guoting , Mu Liqiang , Li Chun
Published: April 2011

Very little is known about the tolerance of ectomycorrhizal fungi to the freezing and repetitive freezing–thawing in northern coniferous forests. Isolates of Cortinarius multiformis , Russula densifolia , Suillus granulatus , and Lactarius deliciosus were exposed to a series of temperatures between +4 and –40 °C. The relative electrolyte leakage test indicated that the lethal temperature for 50% of samples was between –7.6 and –13.7 °C. Resume growth experiments showed that the 4 species of ectomycorrhizal fungi had a relatively high tolerance to the low temperatures, with L. deliciosus having the highest tolerance and C. multiformis the lowest. The repeated freezing–thawing delayed the growth of mycelium, which decreased with an increase in the number of freeze–thaw cycles.
DETERMINATION OF DENSITY-OF-STATES OF NANOCLUSTER CARBON THIN FILMS MIS STRUCTURE USING CAPACITANCE–VOLTAGE TECHNIQUE
Authors: DE SHOUNAK , GOPE JHUMA , SATYANARAYANA B. S. , PANWAR O. S. , RAO MOHAN
Published: April 2011

Nanocluster carbon thin films (NC) were deposited at room temperature by cathodic arc process. These films were clustered, amorphous and disordered in nature which is verified using Raman spectroscopy. Density of defect states (DOS), which influences electronic and optical properties, were determined from the capacitance–voltage (C–V) characteristic of Al / NC / c - Si metal–insulator–semiconductor (MIS) structure near the Fermi level of undoped samples. Dielectric constant of the films was also estimated using the same technique. The DOS were found to be varying from 5.68 × 1016 to 4.9 × 1019 cm-3. The dielectric constant varied between 2.76 to 11.8.
EFFECTS OF HYDROPHOBIC SURFACE NANOBUBBLES ON THE FLOW IN NANOCHANNELS
Authors: XIE HUI , LIU CHAO
Published: April 2011

It has been demonstrated that there are nanobubbles on hydrophobic surface. Molecular dynamics simulation was adopted to investigate the impacts of the hydrophobic surface nanobubbles on fluid flow in nanochannel. A method for calculating the velocity of nanobubbles is presented. The results show that the bubbles on two plates enhance the velocity slip and disturb the flow. The behavior is attributed to the attractive force between nanobubbles.
HEDGING SWING OPTIONS
Authors: RODRÍGUEZ JESÚS F.
Published: April 2011

We study models for electricity pricing and derivatives in the context of a deregulated market setting. In particular we value swing options, since these are the electricity derivatives that attract the most attention from market participants. These are American style options in that they allow for multiple exercises subject to a set of constraints on the consumption process. Through the use of a penalty function, we generalize the problem by allowing for the consumption restrictions to be broken. We characterize the price function as a stochastic optimal control problem, and show that the option is exercised in a bang-bang fashion. The value of the swing option is the solution to a backward stochastic differential equation, and we show how European calls, along with forward contracts, can be used to hedge them.
A PHYLLOTACTIC APPROACH TO THE STRUCTURE OF COLLAGEN FIBRILS
Authors: CHARVOLIN JEAN , SADOC JEAN-FRANÇOIS
Published: April 2011

Collagen fibrils, cable-like assemblies of long biological molecules, the so-called triple helices, are dominant components of connective tissues. Their determinant morphological and functional roles motivated a large number of studies concerning their formation and structure. However, these two points are still open questions and, particularly, that of the lateral assembly of the triple helices which is certainly dense but not strictly that of a well-ordered molecular crystal. We examine here the geometrical template provided by the algorithm of phyllotaxis which gives to each element of an assembly of points or parallel rods the most homogeneous and isotropic dense environment in a situation of cylindrical symmetry. The scattered intensity obtained from a phyllotactic distribution of triple helices in collagen fibrils presents features which could contribute to the scattering observed along the equatorial direction of their X-ray patterns. Following this approach, the aggregation of triple helices in fibrils should be considered within the frame of soft condensed matter studies rather than that of molecular crystal studies.
Effects of estradiol on ischemic factor-induced astrocyte swelling and AQP4 protein abundance
Authors: Rutkowsky Jennifer M. , Wallace Breanna K. , Wise Phyllis M. , O'Donnell Martha E.
Published: April 2011

In the early hours of ischemic stroke, cerebral edema forms as Na, Cl, and water are secreted across the blood-brain barrier (BBB) and astrocytes swell. We have shown previously that ischemic factors, including hypoxia, aglycemia, and arginine vasopressin (AVP), stimulate BBB Na-K-Cl cotransporter (NKCC) and Na/H exchanger (NHE) activities and that inhibiting NKCC and/or NHE by intravenous bumetanide and/or HOE-642 reduces edema and infarct in a rat model of ischemic stroke. Estradiol also reduces edema and infarct in this model and abolishes ischemic factor stimulation of BBB NKCC and NHE. There is evidence that NKCC and NHE also participate in ischemia-induced swelling of astrocytes. However, little is known about estradiol effects on astrocyte cell volume. In this study, we evaluated the effects of AVP (100 nM), hypoxia (7.5% O2), aglycemia, hypoxia (2%)/aglycemia [oxygen glucose deprivation (OGD)], and estradiol (1–100 nM) on astrocyte cell volume using 3- O-methyl-d-[3H]glucose equilibration methods. We found that AVP, hypoxia, aglycemia, and OGD (30 min to 5 h) each significantly increased astrocyte cell volume, and that estradiol (30–180 min) abolished swelling induced by AVP or hypoxia, but not by aglycemia or OGD. Bumetanide and/or HOE-642 also abolished swelling induced by AVP but not aglycemia. Abundance of aquaporin-4, known to participate in ischemia-induced astrocyte swelling, was significantly reduced following 7-day but not 2- or 3-h estradiol exposures. Our findings suggest that hypoxia, aglycemia, and AVP each contribute to ischemia-induced astrocyte swelling, and that the edema-attenuating effects of estradiol include reduction of hypoxia- and AVP-induced astrocyte swelling and also reduction of aquaporin-4 abundance.
Upregulation of the CaV1.1-ryanodine receptor complex in a rat model of critical illness myopathy
Authors: Kraner Susan D. , Wang Qingbo , Novak Kevin R. , Cheng Dongmei , Cool David R. , Peng Junmin , Rich Mark M.
Published: April 2011

The processes that trigger severe muscle atrophy and loss of myosin in critical illness myopathy (CIM) are poorly understood. It has been reported that muscle disuse alters Ca2+handling by the sarcoplasmic reticulum. Since inactivity is an important contributor to CIM, this finding raises the possibility that elevated levels of the proteins involved in Ca2+handling might contribute to development of CIM. CIM was induced in 3- to 5-mo-old rats by sciatic nerve lesion and infusion of dexamethasone for 1 wk. Western blot analysis revealed increased levels of ryanodine receptor (RYR) isoforms-1 and -2 as well as the dihydropyridine receptor/voltage-gated calcium channel type 1.1 (DHPR/CaV1.1). Immunostaining revealed a subset of fibers with elevation of RYR1 and CaV1.1 that had severe atrophy and disorganization of sarcomeres. These findings suggest increased Ca2+release from the sarcoplasmic reticulum may be an important contributor to development of CIM. To assess the endogenous functional effects of increased intracellular Ca2+in CIM, proteolysis of α-fodrin, a well-known target substrate of Ca2+-activated proteases, was measured and found to be 50% greater in CIM. There was also selective degradation of myosin heavy chain relative to actin in CIM muscle. Taken together, our findings suggest that increased Ca2+release from the sarcoplasmic reticulum may contribute to pathology in CIM.
Ion transport mechanisms linked to bicarbonate secretion in the esophageal submucosal glands
Authors: Abdulnour-Nakhoul Solange , Nakhoul Hani N. , Kalliny Medhat I. , Gyftopoulos Alex , Rabon Edd , Doetjes Rienk , Brown Karen , Nakhoul Nazih L.
Published: April 2011

The esophageal submucosal glands (SMG) secrete HCO3−and mucus into the esophageal lumen, where they contribute to acid clearance and epithelial protection. This study characterized the ion transport mechanisms linked to HCO3−secretion in SMG. We localized ion transporters using immunofluorescence, and we examined their expression by RT-PCR and in situ hybridization. We measured HCO3−secretion by using pH stat and the isolated perfused esophagus. Using double labeling with Na+-K+-ATPase as a marker, we localized Na+-coupled bicarbonate transporter (NBCe1) and Cl−-HCO3−exchanger (SLC4A2/AE2) to the basolateral membrane of duct cells. Expression of cystic fibrosis transmembrane regulator channel (CFTR) was confirmed by immunofluorescence, RT-PCR, and in situ hybridization. We identified anion exchanger SLC26A6 at the ducts' luminal membrane and Na+-K+-2Cl−(NKCC1) at the basolateral membrane of mucous and duct cells. pH stat experiments showed that elevations in cAMP induced by forskolin or IBMX increased HCO3−secretion. Genistein, an activator of CFTR, which does not increase intracellular cAMP, also stimulated HCO3−secretion, whereas glibenclamide, a Cl−channel blocker, and bumetanide, a Na+-K+-2Cl−blocker, decreased it. CFTRinh-172, a specific CFTR channel blocker, inhibited basal HCO3−secretion as well as stimulation of HCO3−secretion by IBMX. This is the first report on the presence of CFTR channels in the esophagus. The role of CFTR in manifestations of esophageal disease in cystic fibrosis patients remains to be determined.
Endothelin-A receptor blockade slows the progression of renal injury in experimental renovascular disease
Authors: Kelsen Silvia , Hall John E. , Chade Alejandro R.
Published: April 2011

Endothelin (ET)-1, a potent renal vasoconstrictor with mitogenic properties, is upregulated by ischemia and has been shown to induce renal injury via the ET-A receptor. The potential role of ET-A blockade in chronic renovascular disease (RVD) has not, to our knowledge, been previously reported. We hypothesized that chronic ET-A receptor blockade would preserve renal hemodynamics and slow the progression of injury of the stenotic kidney in experimental RVD. Renal artery stenosis, a major cause of chronic RVD, was induced in 14 pigs and observed for 6 wk. In half of the pigs, chronic ET-A blockade was initiated (RVD+ET-A, 0.75 mg·kg−1·day−1) at the onset of RVD. Single-kidney renal blood flow, glomerular filtration rate, and perfusion were quantified in vivo after 6 wk using multidetector computer tomography. Renal microvascular density was quantified ex vivo using three-dimensional microcomputer tomography, and growth factors, inflammation, apoptosis, and fibrosis were determined in renal tissue. The degree of stenosis and increase in blood pressure were similar in RVD and RVD+ET-A pigs. Renal hemodynamics, function, and microvascular density were decreased in the stenotic kidney but preserved by ET-A blockade, accompanied by increased renal expression of vascular endothelial growth factor, hepatocyte growth factor, and downstream mediators such as phosphorilated-Akt, angiopoietins, and endothelial nitric oxide synthase. ET-A blockade also reduced renal apoptosis, inflammation, and glomerulosclerosis. This study shows that ET-A blockade slows the progression of renal injury in experimental RVD and preserves renal hemodynamics, function, and microvascular density in the stenotic kidney. These results support a role for ET-1/ET-A as a potential therapeutic target in chronic RVD.
Effect of medial calcification on vascular function in uremia
Authors: Sutliff Roy L. , Walp Erik R. , El-Ali Alexander M. , Elkhatib Stacey , Lomashvili Koba A. , O'Neill W. Charles
Published: April 2011

The contribution of medial calcification to vascular dysfunction in renal failure is unknown. Vascular function was measured ex vivo in control, noncalcified uremic, and calcified uremic aortas from rats with adenine-induced renal failure. Plasma urea was 16 ± 4, 93 ± 14, and 110 ± 25 mg/dl, and aortic calcium content was 27 ± 4, 29 ± 2, and 4,946 ± 1,616 nmol/mg dry wt, respectively, in the three groups. Maximal contraction by phenylephrine (PE) or KCl was reduced 53 and 63% in uremic aortas, and sensitivity to KCl but not PE was increased. Maximal relaxation to acetylcholine was impaired in uremic aortas (30 vs. 65%), and sensitivity to nitroprusside was also reduced, indicating some impairment of endothelium-independent relaxation as well. None of these parameters differed between calcified and noncalcified uremic aortas. However, aortic compliance was reduced in calcified aortas, ranging from 17 to 61% depending on the severity of calcification. We conclude that uremic vascular calcification, even when not severe, significantly reduces arterial compliance. Vascular smooth muscle and endothelial function are altered in renal failure but are not affected by medial calcification, even when severe.
Effects of endurance training on apoptotic susceptibility in striated muscle
Authors: Vainshtein Anna , Kazak Lawrence , Hood David A.
Published: April 2011

An increase in the production of reactive oxygen species occurs with muscle disuse, ischemic cardiomyopathy, and conditions that arise with senescence. The resulting oxidative stress is associated with apoptosis-related myopathies. Recent research has suggested that chronic exercise is protective against mitochondrially mediated programmed cell death. To further investigate this, we compared soleus (Sol) and cardiac muscles of voluntary wheel-trained (T; 10 wk) and untrained (C) animals. Training produced a 52% increase in muscle cytochrome c oxidase (COX) activity. Sol and left ventricle (LV) strips were isolated and incubated in vitro with H2O2 for 4 h. Strips were then fractionated into cytosolic and mitochondrial fractions. Whole muscle apoptosis-inducing factor (AIF) and Bax/Bcl-2 levels were reduced in both the Sol and LV from T animals. H2O2 treatment induced increases in JNK phosphorylation, cofilin-2 localization to the mitochondria, as well as cytosolic AIF in both Sol and LV of T and C animals, respectively. Mitochondrial Bax and cytosolic cytochrome c were augmented under oxidative stress in the LV only. The H2O2-induced increases in P-JNK, mitochondrial Bax, and cytosolic AIF were ablated in the LV of T animals. These data suggest that short-term oxidative stress can induce apoptotic signaling in striated muscles in vitro. In addition, training can attenuate oxidative stress-induced apoptotic signaling in a tissue-specific manner, with an effect that is most prominent in cardiac muscle.
Physiological identification and infralimbic responsiveness of rat intercalated amygdala neurons
Authors: Amir Alon , Amano Taiju , Pare Denis
Published: April 2011

Intercalated (ITC) amygdala neurons are thought to play a critical role in the extinction of conditioned fear. However, several factors hinder progress in studying ITC contributions to extinction. First, although extinction is usually studied in rats and mice, most ITC investigations were performed in guinea pigs or cats. Thus it is unclear whether their connectivity is similar across species. Second, we lack criteria to identify ITC cells on the basis of their discharge pattern. As a result, key predictions of ITC extinction models remain untested. Among these, ITC cells were predicted to be strongly excited by infralimbic inputs, explaining why infralimbic inhibition interferes with extinction. To study the connectivity of ITC cells, we labeled them with neurobiotin during patch recordings in slices of the rat amygdala. This revealed that medially located ITC cells project topographically to the central nucleus and to other ITC clusters located more ventrally. To study the infralimbic responsiveness of ITC cells, we performed juxtacellular recording and labeling of amygdala cells with neurobiotin in anesthetized rats. All ITC cells were orthodromically responsive to infralimbic stimuli, and their responses usually consisted of high-frequency (∼350 Hz) trains of four to six spikes, a response pattern never seen in neighboring amygdala nuclei. Overall, our results suggest that the connectivity of ITC cells is conserved across species and that ITC cells are strongly responsive to infralimbic stimuli, as predicted by extinction models. The unique response pattern of ITC cells to infralimbic stimuli can now be used to identify them in fear conditioning experiments.
Photon counting, censor corrections, and lifetime imaging for improved detection in two-photon microscopy
Authors: Driscoll Jonathan D. , Shih Andy Y. , Iyengar Satish , Field Jeffrey J. , White G. Allen , Squier Jeffrey A. , Cauwenberghs Gert , Kleinfeld David
Published: April 2011

We present a high-speed photon counter for use with two-photon microscopy. Counting pulses of photocurrent, as opposed to analog integration, maximizes the signal-to-noise ratio so long as the uncertainty in the count does not exceed the gain-noise of the photodetector. Our system extends this improvement through an estimate of the count that corrects for the censored period after detection of an emission event. The same system can be rapidly reconfigured in software for fluorescence lifetime imaging, which we illustrate by distinguishing between two spectrally similar fluorophores in an in vivo model of microstroke.
Altered responses of MeCP2-deficient mouse brain stem to severe hypoxia
Authors: Kron Miriam , Zimmermann Jasper L. , Dutschmann Mathias , Funke Frank , Müller Michael
Published: April 2011

Rett syndrome (RTT) patients suffer from respiratory arrhythmias with frequent apneas causing intermittent hypoxia. In a RTT mouse model (methyl-CpG-binding protein 2-deficient mice; Mecp2−/ y) we recently discovered an enhanced hippocampal susceptibility to hypoxia and hypoxia-induced spreading depression (HSD). In the present study we investigated whether this also applies to infant Mecp2−/ ybrain stem, which could become life-threatening due to failure of cardiorespiratory control. HSD most reliably occurred in the nucleus of the solitary tract (NTS) and the spinal trigeminal nucleus (Sp5). HSD susceptibility of the Mecp2−/ yNTS and Sp5 was increased on 8 mM K+-mediated conditioning. 5-HT1Areceptor stimulation with 8-hydroxy-2-(di-propylamino)tetralin (8-OH-DPAT) postponed HSD by up to 40%, mediating genotype-independent protection. The deleterious impact of HSD on in vitro respiration became obvious in rhythmically active slices, where HSD propagation into the pre-Bötzinger complex (pre-BötC) immediately arrested the respiratory rhythm. Compared with wild-type, the Mecp2−/ ypre-BötC was invaded less frequently by HSD, but if so, HSD occurred earlier. On reoxygenation, in vitro rhythms reappeared with increased frequency, which was less pronounced in Mecp2−/ yslices. 8-OH-DPAT increased respiratory frequency but failed to postpone HSD in the pre-BötC. Repetitive hypoxia facilitated posthypoxic recovery only if HSD occurred. In 57% of Mecp2−/ yslices, however, HSD spared the pre-BötC. Although this occasionally promoted residual hypoxic respiratory activity (“gasping”), it also prolonged the posthypoxic recovery, and thus the absence of central inspiratory drive, which in vivo would lengthen respiratory arrest. In view of the breathing disorders in RTTs, the increased hypoxia susceptibility of MeCP2-deficient brain stem potentially contributes to life-threatening disturbances of cardiorespiratory control.
Neurons in the human hippocampus and amygdala respond to both low- and high-level image properties
Authors: Steinmetz Peter N. , Cabrales Elaine , Wilson Michael S. , Baker Christopher P. , Thorp Christopher K. , Smith Kris A. , Treiman David M.
Published: April 2011

A large number of studies have demonstrated that structures within the medial temporal lobe, such as the hippocampus, are intimately involved in declarative memory for objects and people. Although these items are abstractions of the visual scene, specific visual details can change the speed and accuracy of their recall. By recording from 415 neurons in the hippocampus and amygdala of human epilepsy patients as they viewed images drawn from 10 image categories, we showed that the firing rates of 8% of these neurons encode image illuminance and contrast, low-level properties not directly pertinent to task performance, whereas in 7% of the neurons, firing rates encode the category of the item depicted in the image, a high-level property pertinent to the task. This simultaneous representation of high- and low-level image properties within the same brain areas may serve to bind separate aspects of visual objects into a coherent percept and allow episodic details of objects to influence mnemonic performance.