bluuebunny/crossref_metadata_2025 huggingface dataset:
EQUIVALENCIES IN THE FISHERY
Authors: CONRAD JON M. , LEARD BENJAMIN P.
Published: July 2012

Abstract We consider the management of a resource by a sole owner whose utility depends on income and leisure. Income is generated from time spent harvesting the resource and time spent working for a wage in the nonfishing sector. Our analysis produces two results. (i) The sole owner maximizing discounted utility will seek to achieve the same steady‐state optimum as a manager seeking to maximize discounted net revenue. (ii) The approach paths to the common steady‐state optimum will be the same if the utility function is linear in income and separable in income and leisure. These equivalencies are illustrated in a numerical example.
POSSIBILITIES AND LIMITATIONS OF USING HISTORIC PROVENANCE TESTS TO INFER FOREST SPECIES GROWTH RESPONSES TO CLIMATE CHANGE
Authors: LEITES LAURA P. , REHFELDT GERALD E. , ROBINSON ANDREW P. , CROOKSTON NICHOLAS L. , JAQUISH BARRY
Published: July 2012

Abstract.  Under projected changes in global climate, the growth and survival of existing forests will depend on their ability to adjust physiologically in response to environmental change. Quantifying their capacity to adjust and whether the response is species‐ or population‐specific is important to guide forest management strategies. New analyses of historic provenance tests data are yielding relevant insights about these responses. Yet, differences between the objectives used to design the experiments and current objectives impose limitations to what can be learned from them. Our objectives are (i) to discuss the possibilities and limitations of using such data to quantify growth responses to changes in climate and (ii) to present a modeling approach that creates a species‐ and population‐specific model. We illustrate the modeling approach for Larix occidentalis Nutt. We conclude that the reanalysis of historic provenance tests data can lead to the identification of species that have population‐specific growth responses to changes in climate, provide estimates of optimum transfer distance for populations and species, and provide estimates of growth changes under different climate change scenarios. Using mixed‐effects modeling techniques is a sound statistical approach to overcome some of the limitations of the data.
Evaluation of antibiotic prescribing patterns in patients receiving sustained low-efficiency dialysis: opportunities for pharmacists
Authors: Harris Laura E , Reaves Anne B , Krauss Amy G , Griner Justin , Hudson Joanna Q
Published: July 2012

Objectives

Sustained low-efficiency dialysis (SLED) is a ‘hybrid’ form of continuous renal replacement therapy; however, there is very limited information on drug disposition during this procedure. Individuals requiring SLED are often critically ill and require antibiotics. The study aim was to evaluate antibiotic orders for patients requiring SLED compared to literature-based recommendations. We also evaluated whether doses were administered as prescribed and assessed clinical and microbiologic cure.

Methods

A retrospective review was performed over a 2-year period for patients who received concurrent SLED and antibiotic therapy. Demographic data, prescribed antibiotic dosing regimens and doses delivered as prescribed were determined for 10 antibiotics: cefepime (C), daptomycin (Da), doripenem (D), gentamicin (G), imipenem-cilastatin (I), linezolid (L), meropenem (M), piperacillin-tazobactam (P), tobramycin (T) and vancomycin (V). Dosing regimens were compared to recommendations from the literature where available. The incidence of clinical and microbiologic cure was also evaluated.

Results

A total of 87 patients met inclusion criteria: mean age 54 ± 14 years, 60% male, 58% white. Prescribed doses were evidence-based for 37% of Da, 97% of L, 15% of M and 7% of V orders. The majority of discrepancies were due to under-dosing. There were 129 (11%) antibiotic doses missed. Of the 13 patients who met criteria for assessment of clinical and microbiologic cure, 10 achieved a microbiologic cure and none reached clinical cure.

Conclusions

Prescribed antibiotic dosing regimens varied substantially and under-dosing was common. There is a need to further define appropriate dosing regimens for antibiotics administered during SLED and determine how pharmacists may help to ensure appropriate therapy.
Computing isogenies between abelian varieties
Authors: Lubicz David , Robert Damien
Published: July 2012

We describe an efficient algorithm for the computation of separable isogenies between abelian varieties represented in the coordinate system given by algebraic theta functions. Let A be an abelian variety of dimension g defined over a field of odd characteristic. Our algorithm comprises two principal steps. First, given a theta null point for A and a subgroup K isotropic for the Weil pairing, we explain how to compute the theta null point corresponding to the quotient abelian variety A/K. Then, from the knowledge of a theta null point of A/K, we present an algorithm to obtain a rational expression for an isogeny from A to A/K. The algorithm that results from combining these two steps can be viewed as a higher-dimensional analog of the well-known algorithm of Vélu for computing isogenies between elliptic curves. In the case where K is isomorphic to (ℤ/ℓℤ)g for ℓ∈ℕ*, the overall time complexity of this algorithm is equivalent to O(log ℓ) additions in A and a constant number of ℓth root extractions in the base field of A. In order to improve the efficiency of our algorithms, we introduce a compressed representation that allows us to encode a point of level 4ℓ of a g-dimensional abelian variety using only g(g+1)/2⋅4g coordinates. We also give formulas for computing the Weil and commutator pairings given input points in theta coordinates.
ATP‐mediated vasodilatation occurs via activation of inwardly rectifying potassium channels in humans
Authors: Crecelius Anne R. , Kirby Brett S. , Luckasen Gary J. , Larson Dennis G. , Dinenno Frank A.
Published: July 2012

Key points

ATP is a substance in the blood vessels that can cause vasodilatation and increase blood flow and oxygen delivery in humans.

The exact signalling pathways that ATP stimulates to cause vasodilatation are not well known.

We show that a large portion of ATP‐mediated vasodilatation occurs through the activation of inwardly rectifying potassium channels (Kir).

Our results lend insight into the vasodilator mechanisms of ATP, a substance that is important for vascular control.

Further, our results may stimulate additional investigations in humans regarding the activation of Kir channels and subsequent vascular hyperpolarization during other physiologically relevant conditions.

Abstract  Circulating ATP possesses unique vasomotor properties in humans and has been hypothesized to play a role in vascular control under a variety of physiological conditions. However, the primary downstream signalling mechanisms underlying ATP‐mediated vasodilatation remain unclear. The purpose of the present experiment was to determine whether ATP‐mediated vasodilatation is independent of nitric oxide (NO) and prostaglandin (PG) synthesis and occurs primarily via the activation of Na+/K+‐ATPase and inwardly rectifying potassium (KIR) channels in humans. In all protocols, young healthy adults were studied and forearm vascular conductance (FVC) was calculated from forearm blood flow (measured via venous occlusion plethysmography) and intra‐arterial blood pressure to quantify local vasodilatation. Vasodilator responses (%ΔFVC) during intra‐arterial ATP infusions were unchanged following combined inhibition of NO and PGs (n= 8; P > 0.05) whereas the responses to KCl were greater (P < 0.05). Combined infusion of ouabain (to inhibit Na+/K+‐ATPase) and barium chloride (BaCl2; to inhibit KIR channels) abolished KCl‐mediated vasodilatation (n= 6; %ΔFVC = 134 ± 13 vs. 4 ± 5%; P < 0.05), demonstrating effective blockade of direct vascular hyperpolarization. The vasodilator responses to three different doses of ATP were inhibited on average 56 ± 5% (n= 16) following combined ouabain plus BaCl2 infusion. In follow‐up studies, BaCl2 alone inhibited the vasodilator responses to ATP on average 51 ± 3% (n= 6), which was not different than that observed for combined ouabain plus BaCl2 administration. Our novel results indicate that the primary mechanism of ATP‐mediated vasodilatation is vascular hyperpolarization via activation of KIR channels. These observations translate in vitro findings to humans in vivo and may help explain the unique vasomotor properties of intravascular ATP in the human circulation.
Bicarbonate‐dependent chloride transport drives fluid secretion by the human airway epithelial cell line Calu‐3
Authors: Shan Jiajie , Liao Jie , Huang Junwei , Robert Renaud , Palmer Melissa L. , Fahrenkrug Scott C. , O’Grady Scott M. , Hanrahan John W.
Published: July 2012

Key points

The mechanisms of anion and fluid transport by airway submucosal glands are not well understood and may differ from those in surface epithelium.

The Calu‐3 cell line is often used as a model for submucosal gland serous cells and has cAMP‐stimulated fluid secretion; however, it does not actively transport chloride under short‐circuit conditions.

In this study we show that fluid secretion requires chloride, bicarbonate and sodium, that chloride is the predominant anion in Calu‐3 secretions, and that a large fraction of the basolateral chloride loading during cAMP stimulation occurs by Cl−/HCO3− exchange.

The results suggest a novel cellular model for anion and fluid secretion by Calu‐3 and submucosal gland acinar cells

Abstract  Anion and fluid secretion are both defective in cystic fibrosis (CF); however, the transport mechanisms are not well understood. In this study, Cl− and HCO3− secretion was measured using genetically matched CF transmembrane conductance regulator (CFTR)‐deficient and CFTR‐expressing cell lines derived from the human airway epithelial cell line Calu‐3. Forskolin stimulated the short‐circuit current (Isc) across voltage‐clamped monolayers, and also increased the equivalent short‐circuit current (Ieq) calculated under open‐circuit conditions. Isc was equivalent to the HCO3− net flux measured using the pH‐stat technique, whereas Ieq was the sum of the Cl− and HCO3− net fluxes. Ieq and HCO3− fluxes were increased by bafilomycin and ZnCl2, suggesting that some secreted HCO3− is neutralized by parallel electrogenic H+ secretion. Ieq and fluid secretion were dependent on the presence of both Na+ and HCO3−. The carbonic anhydrase inhibitor acetazolamide abolished forskolin stimulation of Ieq and HCO3− secretion, suggesting that HCO3− transport under these conditions requires catalysed synthesis of carbonic acid. Cl− was the predominant anion in secretions under all conditions studied and thus drives most of the fluid transport. Nevertheless, 50–70% of Cl− and fluid transport was bumetanide‐insensitive, suggesting basolateral Cl− loading by a sodium–potassium–chloride cotransporter 1 (NKCC1)‐independent mechanism. Imposing a transepithelial HCO3− gradient across basolaterally permeabilized Calu‐3 cells sustained a forskolin‐stimulated current, which was sensitive to CFTR inhibitors and drastically reduced in CFTR‐deficient cells. Net HCO3− secretion was increased by bilateral Cl− removal and therefore did not require apical Cl−/HCO3− exchange. The results suggest a model in which most HCO3− is recycled basolaterally by exchange with Cl−, and the resulting HCO3−‐dependent Cl− transport provides an osmotic driving force for fluid secretion.
Numerical and Hardware-In-the-Loop Tools for the Design of Very High Speed Pantograph-Catenary Systems
Authors: Bruni Stefano , Bucca Giuseppe , Collina Andrea , Facchinetti Alan
Published: July 2012

To be competitive with other transport means for a wider distance range, high-speed trains need to increase their revenue service speed. Due to this need, improving the pantograph-catenary interaction to ensure appropriate current collection in spite of the increased dynamic effects and the larger electrical power required represents one of the most serious technical issues to be solved. The aim of this paper is to discuss the use of numerical and hybrid (hardware in the loop) simulation tools in the design of new overhead lines for a speed of 360 km/h. A validation of both simulation tools is performed using line measurements as a point of comparison; then the validated simulation approaches are used to quantitatively assess the effectiveness of some catenary design options.
Bistable Compliant Mechanisms: Corrected Finite Element Modeling for Stiffness Tuning and Preloading Incorporation
Authors: Dunning A. G. , Tolou N. , Pluimers P. P. , Kluit L. F. , Herder J. L.
Published: July 2012

Bistable straight-guided buckling beams are essential mechanisms for precision engineering, compliant mechanisms, and MEMS. However, a straightforward and accurate numerical modeling have not been available. When preloading effects must be included, numerical modeling becomes an even more challenging problem. This article presents a straightforward numerical model for bistable straight-guided buckling beams, which includes preloading effects as well. Adjusting the bistable force–displacement characteristic by variation of design parameters and preloading is also investigated. Both lumped compliance and distributed compliance are considered in this work. In order to validate the model, measurements have been performed. It was shown that a small precurvature of bistable straight-guided buckling beams is crucial to avoid convergence into higher order buckling modes in nonlinear analysis of ANSYS™ and to obtain reliable results. Transient analysis using ANSYS™ with subsequent preloading and motion displacements can incorporate preloading effects. Moreover, the model correction allows accurate description of the increased symmetry and energy efficiency of the bistable behavior in case of increasing (in order of effectiveness) the initial angle and preloading for the case of distributed compliance. This behavior was observed by increasing the initial angle, thickness, and length of the rigid segment for the case of lumped compliance.
Low-temperature oriented growth of vanadium dioxide films on CoCrTa metal template on Si and vertical metal–insulator transition
Authors: Okimura Kunio , Mian Md.Suruz
Published: July 2012

The authors achieved oriented growth of vanadium dioxide (VO2) films on CoCrTa metal template grown on an Si substrate. Low-temperature (∼250 °C) deposition of VO2 films using inductively coupled-plasma-assisted sputtering technique realized an abrupt interface between VO2 and CoCrTa layers, suppressing the oxidation and diffusion of metal components. The films revealed a metal–insulator transition with resistance change of over 2 orders of magnitude. The CoCrTa film, in which Co hexagonal crystalline grains with c-axis orientation were surrounded by segregated Cr and Ta, serves for the oriented growth of VO2 crystalline film, enabling higher orders of transition in resistance and low voltage switching, even for the vertical (out-of-plane) direction.
Schottky barrier and attenuation length for hot hole injection in nonepitaxial Au on p-type GaAs
Authors: Sitnitsky Ilona , Garramone John J. , Abel Joseph , Xu Peng , Barber Steven D. , Ackerman Matt L. , Kevin Schoelz J. , Thibado Paul M. , LaBella Vincent P.
Published: July 2012

Ballistic electron emission microscopy (BEEM) was performed to obtain current versus bias characteristics of nonepitaxial nanometer-thick Au on p-type GaAs in order to accurately measure the local Schottky barrier height. Hole injection BEEM data were averaged from thousands of spectra for various Au film thicknesses and then used to determine the attenuation length of the energetic charge carriers as a function of tip bias. The authors report an increase in attenuation length at biases near the Schottky barrier, providing evidence for the existence of coherent BEEM currents in Schottky diodes. These results provide additional evidence for the conservation of the parallel momentum of charge carriers at the metal–semiconductor interface.
Growth of epitaxial oxides on silicon using atomic layer deposition: Crystallization and annealing of TiO2 on SrTiO3-buffered Si(001)
Authors: McDaniel Martin D. , Posadas Agham , Ngo Thong Q. , Dhamdhere Ajit , Smith David J. , Demkov Alexander A. , Ekerdt John G.
Published: July 2012

Epitaxial anatase titanium dioxide (TiO2) films have been grown by atomic layer deposition (ALD) on Si(001) substrates using a strontium titanate (STO) buffer layer without any amorphous SiOx layer at the STO–Si interface. Four unit cells of STO grown by molecular beam epitaxy (MBE) serve as the surface template for ALD growth. To preserve the quality of the MBE-grown STO, the samples were transferred in situ from the MBE chamber to the ALD chamber. The growth of TiO2 was achieved using titanium isopropoxide and water as the coreactants at a substrate temperature of 250 °C. In situ x-ray photoelectron spectroscopy analysis revealed that the ALD process did not induce Si–O bonding at the STO–Si interface. Slight improvement in crystallinity of the TiO2 film was achieved through in situ annealing under vacuum (10−9 Torr) at 450–600 °C. However, the amount of Si–O bonding increased following annealing at temperatures greater than 250 °C. X-ray diffraction revealed that TiO2 films annealed at a temperature of 250 °C in vacuum (10−9 Torr) for 1 h were the anatase phase and well crystallized. The results indicate that careful consideration of growth temperature and annealing conditions may allow epitaxial oxide films to be grown by ALD on STO-buffered Si(001) substrates without formation of an amorphous SiOx layer.
Ge concentrations in pile-up layers of sub-100-nm SiGe films for nano-structuring by thermal oxidation
Authors: Long Ethan , Galeckas Augustinas , Kuznetsov Andrej Yu
Published: July 2012

The data and analysis presented herein aims to facilitate the design and manufacture of SiGe based nanostructures and devices by describing the enhancement of Ge concentration in sub-100-nm thin films of SiGe by dry thermal oxidation. Thin films of SiGe were restructured by using thermal oxidation induced self-organization of Si and Ge atoms to create a layer of enhanced Ge concentration. The dry thermal oxidations were carried out at temperatures between 800 °C and 1000 °C. The influence of temperature on the Ge content at the oxidation front, as measured by x-ray diffraction, is examined and supported by simulation results. A model for determination of the Ge content in the pile-up layer is presented along with appropriate values for the activation energy and pre-exponential constant for diffusion of Si in Si1-XGeX. This model may also be used for determination of the diffusivity of Si in Si1-XGeX by fitting the model results to the measured Ge concentration in the pile-up layer. It is observed that the Ge content at the oxidation front is a function of temperature and varies linearly between 64% at 800 °C and 36% at 1000 °C. However, the Ge content is largely independent of oxide thickness and the Ge content in the initial SiGe layer. When the Ge concentration at the oxidation front is considered, the experimental results presented here indicate that the oxidation rates of SiGe closely match those of Si and provide evidence that the presence of Ge in very thin films of SiGe does not lead to enhanced or retarded oxidation rates as compared to Si.
Protecting Cancer Cells from Death
Authors: Gough Nancy R.
Published: July 2012

Tumor cells use the chemokines CXCL1 and 2 to recruit myeloid cells that produce signals that enhance the tumor cells’ survival.
Mature Pseudomonas aeruginosa Biofilms Prevail Compared to Young Biofilms in the Presence of Ceftazidime
Authors: Bowler Laura L. , Zhanel George G. , Ball T. Blake , Saward Laura L.
Published: July 2012

Phenotypic tolerances to antibiotics of mature and young
Pseudomonas aeruginosa
PAO1 biofilms and released planktonic bacteria were compared for four antibiotics. Resistance levels were similar for gentamicin and ciprofloxacin but differed for ceftazidime and meropenem. β-Lactamase mapping showed that, after 5 h of ceftazidime exposure, mature biofilms produced more β-lactamase than young biofilms, facilitating the growth of released planktonic bacteria. This shows the importance of early treatment and choice of antibiotics for
P. aeruginosa
biofilm infections.
A Whole-Cell Phenotypic Screening Platform for Identifying Methylerythritol Phosphate Pathway-Selective Inhibitors as Novel Antibacterial Agents
Authors: Testa Charles A. , Johnson L. Jeffrey
Published: July 2012

Isoprenoid biosynthesis is essential for survival of all living organisms. More than 50,000 unique isoprenoids occur naturally, with each constructed from two simple five-carbon precursors: isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Two pathways for the biosynthesis of IPP and DMAPP are found in nature. Humans exclusively use the mevalonate (MVA) pathway, while most bacteria, including all Gram-negative and many Gram-positive species, use the unrelated methylerythritol phosphate (MEP) pathway. Here we report the development of a novel, whole-cell phenotypic screening platform to identify compounds that selectively inhibit the MEP pathway. Strains of
Salmonella enterica
serovar Typhimurium were engineered to have separately inducible MEP (native) and MVA (nonnative) pathways. These strains, RMC26 and CT31-7d, were then used to differentiate MVA pathway- and MEP pathway-specific perturbation. Compounds that inhibit MEP pathway-dependent bacterial growth but leave MVA-dependent growth unaffected represent MEP pathway-selective antibacterials. This screening platform offers three significant results. First, the compound is antibacterial and is therefore cell permeant, enabling access to the intracellular target. Second, the compound inhibits one or more MEP pathway enzymes. Third, the MVA pathway is unaffected, suggesting selectivity for targeting the bacterial versus host pathway. The cell lines also display increased sensitivity to two reported MEP pathway-specific inhibitors, further biasing the platform toward inhibitors selective for the MEP pathway. We demonstrate development of a robust, high-throughput screening platform that combines phenotypic and target-based screening that can identify MEP pathway-selective antibacterials simply by monitoring optical density as the readout for cell growth/inhibition.
Polyclonal Mucosa-Associated Invariant T Cells Have Unique Innate Functions in Bacterial Infection
Authors: Chua Wei-Jen , Truscott Steven M. , Eickhoff Christopher S. , Blazevic Azra , Hoft Daniel F. , Hansen Ted H.
Published: July 2012

Mucosa-associated invariant T (MAIT) cells are a unique population of αβ T cells in mammals that reside preferentially in mucosal tissues and express an invariant Vα paired with limited Vβ T-cell receptor (TCR) chains. Furthermore, MAIT cell development is dependent upon the expression of the evolutionarily conserved major histocompatibility complex (MHC) class Ib molecule MR1. Usingin vitroassays, recent studies have shown that mouse and human MAIT cells are activated by antigen-presenting cells (APCs) infected with diverse microbes, including numerous bacterial strains and yeasts, but not viral pathogens. However, whether MAIT cells play an important, and perhaps unique, role in controlling microbial infection has remained unclear. To probe MAIT cell function, we show here that purified polyclonal MAIT cells potently inhibit intracellular bacterial growth ofMycobacterium bovisBCG in macrophages (MΦ) in coculture assays, and this inhibitory activity was dependent upon MAIT cell selection by MR1, secretion of gamma interferon (IFN-γ), and an innate interleukin 12 (IL-12) signal from infected MΦ. Surprisingly, however, the cognate recognition of MR1 by MAIT cells on the infected MΦ was found to play only a minor role in MAIT cell effector function. We also report that MAIT cell-deficient mice had higher bacterial loads at early times after infection compared to wild-type (WT) mice, demonstrating that MAIT cells play a unique role among innate lymphocytes in protective immunity against bacterial infection.
Identification of Genes That Contribute to the Pathogenesis of Invasive Pneumococcal Disease by
In Vivo
Transcriptomic Analysis
Authors: Ogunniyi Abiodun D. , Mahdi Layla K. , Trappetti Claudia , Verhoeven Nadine , Mermans Daphne , Van der Hoek Mark B. , Plumptre Charles D. , Paton James C.
Published: July 2012

Streptococcus pneumoniae
(the pneumococcus) continues to be responsible for a high level of global morbidity and mortality resulting from pneumonia, bacteremia, meningitis, and otitis media. Here we have used a novel technique involving niche-specific, genome-wide
in vivo
transcriptomic analyses to identify genes upregulated in distinct niches during pathogenesis after intranasal infection of mice with serotype 4 or 6A pneumococci. The analyses yielded 28 common, significantly upregulated genes in the lungs relative to those in the nasopharynx and 25 significantly upregulated genes in the blood relative to those in the lungs in both strains, some of which were previously unrecognized. The role of five upregulated genes from either the lungs or the blood in pneumococcal pathogenesis and virulence was then evaluated by targeted mutagenesis. One of the mutants (Δ
malX
) was significantly attenuated for virulence in the lungs, two (Δ
aliA
and Δ
ilvH
) were significantly attenuated for virulence in the blood relative to the wild type, and two others (Δ
cbiO
and Δ
piuA
) were completely avirulent in a mouse intranasal challenge model. We also show that the products of
aliA
,
malX
, and
piuA
are promising candidates for incorporation into multicomponent protein-based pneumococcal vaccines currently under development. Importantly, we suggest that this new approach is a viable complement to existing strategies for the discovery of genes critical to the distinct stages of invasive pneumococcal disease and potentially has broad application for novel protein antigen discovery in other pathogens such as
S. pyogenes
,
Haemophilus influenzae
type b, and
Neisseria meningitidis
.
The Meningococcal Minor Pilin PilX Is Responsible for Type IV Pilus Conformational Changes Associated with Signaling to Endothelial Cells
Authors: Brissac Terry , Mikaty Guillain , Duménil Guillaume , Coureuil Mathieu , Nassif Xavier
Published: July 2012

Neisseria meningitidis
crosses the blood-brain barrier (BBB) following the activation of the β2-adrenergic receptor by the type IV pili (TFP). Two components of the type IV pili recruit the β2-adrenergic receptor, the major pilin PilE and the minor pilin PilV. Here, we report that a strain deleted of PilX, one of the three minor pilins, is defective in endothelial cell signaling. The signaling role of PilX was abolished when pili were not retractable. Purified PilX was unable to recruit the β2-adrenergic receptor, thus suggesting that PilX was playing an indirect role in endothelial cell signaling. Considering the recent finding that type IV pili can transition into a new conformation (N. Biais, D. L. Higashi, J. Brujic, M. So, and M. P. Sheetz, Proc. Natl. Acad. Sci. U. S. A. 107:11358–11363, 2010), we hypothesized that PilX was responsible for a structural modification of the fiber and allowed hidden epitopes to be exposed. To confirm this hypothesis, we showed that a monoclonal antibody which recognizes a linear epitope of PilE bound fibers only when bacteria adhered to endothelial cells. On the other hand, this effect was not observed in PilX-deleted pili. A deletion of a region of PilX exposed on the surface of the fiber had phenotypical consequences identical to those of a PilX deletion. These data support a model in which surface-exposed motifs of PilX use forces generated by pilus retraction to promote conformational changes required for TFP-mediated signaling.
Candida albicans and Bacterial Microbiota Interactions in the Cecum during Recolonization following Broad-Spectrum Antibiotic Therapy
Authors: Mason Katie L. , Erb Downward John R. , Mason Kelly D. , Falkowski Nicole R. , Eaton Kathryn A. , Kao John Y. , Young Vincent B. , Huffnagle Gary B.
Published: July 2012

Candida albicans
is a normal member of the gastrointestinal (GI) tract microbiota of healthy humans, but during host immunosuppression or alterations in the bacterial microbiota,
C. albicans
can disseminate and cause life-threatening illness. The bacterial microbiome of the GI tract, including lactic acid bacteria (LAB), plays a vital role in preventing fungal invasion. However, little is known about the role of
C. albicans
in shaping the bacterial microbiota during antibiotic recovery. We investigated the fungal burdens in the GI tracts of germfree mice and mice with a disturbed microbiome to demonstrate the role of the microbiota in preventing
C. albicans
colonization. Histological analysis demonstrated that colonization with
C. albicans
during antibiotic treatment does not trigger overt inflammation in the murine cecum. Bacterial diversity is reduced long term following cefoperazone treatment, but the presence of
C. albicans
during antibiotic recovery promoted the recovery of bacterial diversity. Cefoperazone diminishes
Bacteroidetes
populations long term in the ceca of mice, but the presence of
C. albicans
during cefoperazone recovery promoted
Bacteroidetes
population recovery. However, the presence of
C. albicans
resulted in a long-term reduction in
Lactobacillus
spp. and promoted
Enterococcus faecalis
populations. Previous studies have focused on the ability of bacteria to alter
C. albicans
; this study addresses the ability of
C. albicans
to alter the bacterial microbiota during nonpathogenic colonization.
Oral ranula in an HIV-positive patient: case report and literature review
Authors: Kinshuck Andrew Jon , Schober Marianne , Kokai George , Clarke Ray
Published: July 2012

We describe the presentation and treatment of an HIV-positive patient with an oral ranula, and review the literature. Ranulas are mucoceles or retention cysts formed by the extravasation of mucus from the sublingual gland, presumably due to continued production of saliva in the presence of ductal obstruction. Oral ranulas in children are rare and the overall prevalence of mucoceles has been reported as 0.08% in children aged 0–12 years. However, there has been a documented increased occurrence in HIV-positive patients. This has been attributed to a blockage of the salivary gland by inflammation and peri-ductal fibrosis following HIV-associated salivary gland disease. Oral lesions may indicate infection with HIV and can also predict progression of HIV to AIDS. The most common oral manifestation is oral candidiasis occurring in 67% of children with HIV. Following this salivary gland disease, periodontal and gingival disease and herpes simplex are the next most common. The exact prevalence of ranulas in an HIV population is not known but the occurrence of a paediatric patient with HIV having at least one oral lesion has been documented as high as 63% and salivary gland disease at 50%. The true extent of the relationship between HIV and ranula is as yet unknown. This represents the only reported case of oral ranula in an HIV-positive patient in the UK.
Bilateral common carotid artery dissection
Authors: Inokuchi Ryota , Sato Hajime , Aoki Yuta , Yahagi Naoki
Published: July 2012

A 63-year-old Japanese man with no significant medical or family history was admitted for sudden consciousness disturbance, left hemiparesis and shock. Physical examination showed internal carotid artery asymmetry on palpation and significant differential blood pressure in both upper arms. A thoracic CT scan showed classic aortic dissection from the ascending aorta through the common iliac artery, classic dissection of the left common carotid artery and an intramural haematoma in the right common carotid artery. The patient's consciousness level gradually improved, and he underwent emergency surgery involving aortic rebuilding with a synthetic graft. Subsequently, he had a good clinical course.
Climate and ground temperature relations at sites across the continuous and discontinuous permafrost zones, northern Canada1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Earth Science Sector (ESS) Contribution 20110128.
Authors: Throop Jennifer , Lewkowicz Antoni G. , Smith Sharon L.
Published: July 2012

Climate – ground temperature relations are examined under a range of conditions for 10 sites across northern Canada. The sites are located between 60°N and 83°N and at elevations of 40 to 1840 m above sea level. They encompass various environmental and climatic conditions, with permafrost temperatures that range from just below 0 to –15 °C. The substrates range from bedrock to fine-grained sediment with high ice content, and vegetation types include coniferous forests in the Mackenzie Valley, shrub tundra at high elevation in the southern Yukon Territory, and polar desert in the High Arctic. Permafrost conditions at all of these sites are determined primarily by air temperature, followed by snow and substrate conditions. The apparent thermal diffusivity is relatively high at colder sites and in bedrock and is lower at sites in sediment with high ice content. Snow has a greater influence on air–ground temperature relations at sites where mean annual air temperatures and active-layer moisture contents are relatively high, leading to physically significant latent heat effects and a slower freeze-back of the active layer.
Lake- and channel-bottom temperatures in the Mackenzie Delta, Northwest Territories1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Project Contribution 03511.
Authors: Ensom T.P. , Burn C.R. , Kokelj S.V.
Published: July 2012

Temperature loggers were placed in 17 lakes and 13 channels throughout the Mackenzie Delta to determine the annual mean bottom temperature ([Formula: see text]) and its spatial and temporal variation for June 2009 – June 2010. The lakes were classified as perched or connected, depending on the duration of their connection to the channel hydrologic system. Average [Formula: see text] values for nine perched lakes, five channels, and eight connected lakes distributed throughout the Mackenzie Delta were 5.5, 4.6, and 3.4 °C, respectively. The range of [Formula: see text] among all instrumented water bodies in the Delta was 4.0 °C. Over the year, bottom temperatures ranged from >20 °C in midsummer to –5 °C in midwinter, with relative stability between freeze-up in mid-October and breakup at the beginning of June. Channel, perched, and connected lake [Formula: see text], and mean annual near-surface ground temperatures of –4 °C in alluvial sedge wetlands and –2.25 °C in forest, were used to estimate that about 60% of Delta lakes and nearly the entire channel network maintain through-taliks.
Factors influencing permafrost temperatures across tree line in the uplands east of the Mackenzie Delta, 2004–20101This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Contribution 03611.
Authors: Palmer M.J. , Burn C.R. , Kokelj S.V.
Published: July 2012

Air and near-surface ground temperatures, late-winter snow conditions, and characteristics of the vegetation cover and soil were measured across the forest–tundra transition in the uplands east of the Mackenzie Delta, Northwest Territories, in 2004–2010. Mean late-winter snow depth decreased northward from 73 cm in the subarctic boreal forest near Inuvik to 22 cm in low-shrub tundra. Annual near-surface ground temperatures decreased northward by 0.1–0.3 °C/km near the northern limit of trees, in association with an abrupt change in snow depth. The rate decreased to 0.01–0.06 °C/km in the tundra. The freezing season is twice as long as the thawing season in the region, so measured differences in the regional ground thermal regime were dominated by the contrast in winter surface conditions between forest and tundra.
Influence of snow on near-surface ground temperatures in upland and alluvial environments of the outer Mackenzie Delta, Northwest Territories1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.
Authors: Morse P.D. , Burn C.R. , Kokelj S.V.
Published: July 2012

Relations between snow cover, active-layer thickness, and near-surface ground temperatures were determined in 2005–2009 for a diverse range of alluvial and upland settings in the outer Mackenzie Delta. Here, the snow cover developed primarily by wind redistribution, with its spatial variation controlled by topography in uplands and vegetation height in alluvial lowlands. Snow cover was the primary influence on freeze-back duration and the mean annual temperature at the top of permafrost (TTOP), with the difference in median TTOP between alluvial (–3.7 °C) and upland (–6.1 °C) settings related to the greater snow depth and soil moisture in the alluvial plain. The active layer was generally deeper in the wet alluvial lowlands, where the average duration of active-layer freeze back (101 days) was nearly double the time taken in the well-drained uplands (55 days). The surface offset (ΔTS; up to 11 °C) dominated the difference between annual mean air temperature (AMAT) and TTOP (ΔT). In alluvial terrain, ΔTS varied with snow depth, but in the uplands, ΔTS was more consistent from site to site. The small thermal offset (<2 °C) was slightly greater in alluvial terrain than in the uplands. The overall range in ΔT (2–10 °C) led to a range during the study of 7.2 °C in TTOP at the sites. The range in AMAT was 1.3 °C but up to 1.7 °C in TTOP at any one site. Permafrost was well established throughout the area except adjacent to channels where TTOP was close to 0 °C.
Geomorphology of a thermo-erosion gully, Bylot Island, Nunavut, Canada1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Project Contribution 043-11.
Authors: Godin Etienne , Fortier Daniel
Published: July 2012

A thermo-erosion gully has been monitored in the valley of glacier C-79 on Bylot Island since 1999. The main channel of the gully reached 390 m in length a few months after its initiation and grew between 38 and 50 m/year over the following decade, for an overall approximated average of 75 m/year. In 2009, the total gully length and area, including the main and relict channels, were 2500 m and 25 000 m2, respectively. Gullies affect snow accumulation, and therefore ground temperature, local water flow, and drainage. Sinkholes, gully heads, pools, baydzherakhi, tunnels, and collapses were grouped as a function of time since gully formation in that area. Sinkholes and tunnels were formed every year after gully inception, and baydzherakhi were found in 3–10 year old sections of the gully. Stabilization of the gully floor and sides took about a decade.
Degradation of permafrost beneath a road embankment enhanced by heat advected in groundwater1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.
Authors: de Grandpré Isabelle , Fortier Daniel , Stephani Eva
Published: July 2012

For the past few decades, northwestern North America has been affected by climate warming, leading to permafrost degradation and instability of the ground. This is problematic for all infrastructure built on permafrost, especially roads and runways. Thaw settlement and soil consolidation promote embankment subsidence and the development of cracks, potholes, and depressions in road pavement. In this study, we investigate highway stability in permafrost terrain at an experimentally built road embankment near Beaver Creek, Yukon. A network of 25 groundwater monitoring wells was installed along the sides of the road to estimate groundwater flow and its thermal impact on the permafrost beneath the road. Data on topography, water-table elevation, ground temperature, and stratigraphy of the soil were collected at the site. The geotechnical properties of each soil layer were determined by laboratory analysis and used to calibrate a two-dimensional groundwater flow model. Field observations showed that water was progressively losing heat as it flowed under the road embankment. Our results suggest that advective heat transfer related to groundwater flow accelerated permafrost degradation under the road embankment.
Cryostratigraphic record of permafrost degradation and recovery following historic (1898–1992) surface disturbances in the Klondike region, central Yukon Territory1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Yukon Geological Survey Contribution 008.
Authors: Calmels Fabrice , Froese Duane G. , Clavano Wendy R.
Published: July 2012

We present a detailed cryostratigraphic reconstruction of the degradation and recovery of near-surface permafrost in the southern Klondike goldfields, central Yukon Territory. Two ice-rich layers are recognized in near-surface permafrost and attributed to thermal impacts following vegetation disturbance. At an undisturbed forest site, the base of the modern active layer is stable. At an adjacent site, where a late twentieth century disturbance of surface vegetation and permafrost degradation occurred, there is evidence of recovery in the form of aggradation (upward shift) of the permafrost table following limited vegetation succession. Underlying both the undisturbed forest and the late twentieth century disturbance is an older thaw unconformity corresponding to a thaw depth of ∼2 m, likely associated with early twentieth century (gold rush era) impacts. Field and air photo surveys allow identification of the nature of the disturbances, while a chronology of the surface disturbance has been established using age estimates from tree rings, and the presence of tritium and post-bomb 14C from organic samples within aggradational ice. Collectively, these data underscore the importance of vegetation cover in maintaining ground temperatures in the discontinuous permafrost zone and suggest that, at least at the study site in recent decades, permafrost shows the potential to recover from disturbance in the modern climatic regime of the region.
RÉPARTITION GALOISIENNE D'UNE CLASSE D'ISOGÉNIE DE COURBES ELLIPTIQUES
Authors: RICHARD RODOLPHE
Published: July 2012

Dans cet article, on montre que les orbites sous Galois des invariants modulaires associés à des courbes elliptiques complexes sans multiplication complexe variant dans une même classe d'isogénie s'équidistribuent dans la courbe modulaire vers la probabilité hyperbolique. La démonstration repose sur des arguments de théorie ergodique, notamment le théorème de Ratner (cf. [A. Eskin et H. Oh, Ergodic theoretic proof of equidistribution of Hecke points, Ergodic Theory Dynam. Systems26(1) (2006) 163–167]), ainsi que sur le théorème de l'image ouverte de Serre [J.-P. Serre, Abelian l-Adic Representations and Elliptic Curves (W. A. Benjamin, New York, 1968); Propriétés Galoisiennes des points d'ordre fini des courbes elliptiques, Invent. Math.15(4) (1972) 259–331] dans le cas où les invariants modulaires considérés sont algébriques sur Q, et des résultats de G. Shimura dans le cas transcendant [Introduction to the Arithmetic Theory of Automorphic Functions, Publications of the Mathematical Society of Japan (Princeton University Press, Princeton, NJ, 1994)].

In this article, it is shown that Galois orbits of invariants associated with non-CM and pairwise isogeneous complex elliptic curves equidistribute in the classical modular curve towards the hyperbolic probability measure. The proof is based on arguments from ergodic theory, especially Ratner's theorem on unipotent flows (cf. [A. Eskin and H. Oh, Ergodic theoretic proof of equidistribution of Hecke points, Ergodic Theory Dynam. Systems26(1) (2006) 163–167]), as well as on Serre's open image theorem [J.-P. Serre, Abelian l-Adic Representations and Elliptic Curves (W. A. Benjamin, New York, 1968); Propriétés Galoisiennes des points d'ordre fini des courbes elliptiques, Invent. Math.15(4) (1972) 259–331] in case of algebraic invariants, and on G. Shimura's work in the transcendant case [Introduction to the Arithmetic Theory of Automorphic Functions, Publications of the Mathematical Society of Japan (Princeton University Press, Princeton, NJ, 1994)].
NONVANISHING OF POINCARÉ SERIES ON AVERAGE
Authors: DAS SOUMYA , GANGULY SATADAL
Published: July 2012

We show that a positive proportion of the Poincaré series do not vanish identically when either the index or the weight varies over an interval of suitable length, the other one being fixed.
ON THE NATURAL DENSITIES OF EIGENVALUES OF A SIEGEL CUSP FORM OF DEGREE 2
Authors: DAS SOUMYA
Published: July 2012

We prove explicit lower bounds for the density of the sets of primes p such that eigenvalues λpof a Siegel cusp form of degree 2 satisfy c2> λp> c1, for c1, c2real. A similar result is also proved for the set of primes such that ∣λp∣ > c.
ASYMPTOTIC FORMULAS FOR CLASS NUMBER SUMS OF INDEFINITE BINARY QUADRATIC FORMS ON ARITHMETIC PROGRESSIONS
Authors: HASHIMOTO YASUFUMI
Published: July 2012

It is known that there is a one-to-one correspondence between equivalence classes of primitive indefinite binary quadratic forms and primitive hyperbolic conjugacy classes of the modular group. Due to such a correspondence, Sarnak obtained the asymptotic formula for the class number sum in order of the fundamental unit by using the prime geodesic theorem for the modular group. In the present paper, we propose asymptotic formulas of the class number sums over discriminants on arithmetic progressions. Since there are relations between the arithmetic properties of the discriminants and the conjugacy classes in the finite groups given by the modular group and its congruence subgroups, we can get the desired asymptotic formulas by arranging the Tchebotarev-type prime geodesic theorem. While such asymptotic formulas were already given by Raulf, the approaches are quite different, the expressions of the leading terms of our asymptotic formulas are simpler and the estimates of the remainder terms are sharper.
MODULAR FORMS AND ELLIPTIC CURVES OVER THE CUBIC FIELD OF DISCRIMINANT –23
Authors: GUNNELLS PAUL E. , YASAKI DAN
Published: July 2012

Let F be the cubic field of discriminant –23 and let [Formula: see text] be its ring of integers. By explicitly computing cohomology of congruence subgroups of [Formula: see text], we computationally investigate modularity of elliptic curves over F.
ON MODULAR GALOIS REPRESENTATIONS MODULO PRIME POWERS
Authors: CHEN IMIN , KIMING IAN , WIESE GABOR
Published: July 2012

We study modular Galois representations mod pm. We show that there are three progressively weaker notions of modularity for a Galois representation mod pm: We have named these "strongly", "weakly", and "dc-weakly" modular. Here, "dc" stands for "divided congruence" in the sense of Katz and Hida. These notions of modularity are relative to a fixed level M. Using results of Hida we display a level-lowering result ("stripping-of-powers of p away from the level"): A mod pm strongly modular representation of some level Npr is always dc-weakly modular of level N (here, N is a natural number not divisible by p). We also study eigenforms mod pm corresponding to the above three notions. Assuming residual irreducibility, we utilize a theorem of Carayol to show that one can attach a Galois representation mod pm to any "dc-weak" eigenform, and hence to any eigenform mod pm in any of the three senses. We show that the three notions of modularity coincide when m = 1 (as well as in other particular cases), but not in general.