bluuebunny/crossref_metadata_2025 huggingface dataset:
Matrix elements of unstable states
Authors: Bernard V. , Hoja D. , Meißner U.-G. , Rusetsky A.
Published: September 2012

Abstract

Using the language of non-relativistic effective Lagrangians, we formulate a systematic framework for the calculation of resonance matrix elements in lattice QCD. The generalization of the Lüscher-Lellouch formula for these matrix elements is derived. We further discuss in detail the procedure of the analytic continuation of the resonance matrix elements into the complex energy plane and investigate the infinite-volume limit.
Derivation of concurrent programs by stepwise scheduling of Event-B models
Authors: Boström Pontus , Degerlund Fredrik , Sere Kaisa , Waldén Marina
Published: September 2012

Concurrent programs are often complex and they are not straightforward to develop and prove correct. Formal development methods based on refinement make it possible not only to derive programs gradually, but also to prove their correctness in a stepwise fashion. Event-B is a formal framework that has been shown useful for developing concurrent and distributed programs. In order to scale to large systems, models can be decomposed into sub-models that can be refined semi-independently and executed in parallel. In this paper, we show how to introduce explicit control flow for the concurrent sub-models in the form of event schedules. The purpose of these schedules is both to provide process-oriented specifications of the programs to complement the state-based approach in Event-B, as well as to facilitate more efficient implementation of the models. The schedules are introduced in a stepwise manner and should be designed to result in a correctness-preserving refinement step. In order to reduce the verification burden on the developers, we provide patterns for schedule introduction, together with their associated proof obligations. We demonstrate our method by applying it on the dining philosophers problem.
Basics and applications of stem cells in the pancreas
Authors: Sekine Keisuke , Taniguchi Hideki
Published: September 2012

Enormous efforts have been made to establish pancreatic stem/progenitor cells as a source for regenerative medicine for the treatment of diabetes mellitus. In recent years, it has been recognized that the self‐renewal of beta cells is the dominant process involved in postnatal beta‐cell regeneration and expansion. Nevertheless, several in‐vitro studies have suggested that ductal or as yet unidentified cells are candidates for pancreatic stem/progenitor cells that can differentiate into multilineage cells, including insulin+ cells. The question remains as to whether beta cells are generated postnatally from stem/progenitor cells other than pre‐existing beta cells. Furthermore, mutated pancreatic stem cells are considered to be prospective candidates for cancer stem cells or tumor‐initiating cells. This review highlights recent progress in pancreatic stem/progenitor cell research.
Comparing new templates and atlas‐based segmentations in the volumetric analysis of brain magnetic resonance images for diagnosing Alzheimer's disease
Authors: Shen Qian , Zhao Weizhao , Loewenstein David A. , Potter Elizabeth , Greig Maria T. , Raj Ashok , Barker Warren , Potter Huntington , Duara Ranjan
Published: September 2012

Background

The segmentation of brain structures on magnetic resonance imaging scans for calculating regional brain volumes, using automated anatomic labeling, requires the use of both brain atlases and templates (template sets). This study aims to improve the accuracy of volumetric analysis of hippocampus (HP) and amygdala (AMG) in the assessment of early Alzheimer's disease (AD) by developing template sets that correspond more closely to the brains of elderly individuals.

Methods

Total intracranial volume and HP and AMG volumes were calculated for elderly subjects with no cognitive impairment (n = 103), with amnestic mild cognitive impairment (n = 68), or with probable AD (n = 46) using the following: (1) a template set consisting of a standard atlas (atlas S), drawn on a young adult male brain, and the widely used Montreal Neurological Institute template (MNI template set); (2) a template set (template S set) in which the template is based on smoothing the image from which atlas S is derived; and (3) a new template set (template E set) in which the template is based on an atlas (atlas E) created from the brain of an elderly individual.

Results

Correspondence to HP and AMG volumes derived from manual segmentation was highest with automated segmentation by template E set, intermediate with template S set, and lowest with the MNI template set. The areas under the receiver operating curve for distinguishing elderly subjects with no cognitive impairment from elderly subjects with amnestic mild cognitive impairment or probable AD and the correlations between HP and AMG volumes and cognitive and functional scores were highest for template E set, intermediate for template S set, and lowest for the MNI template set.

Conclusions

The accuracy of automated anatomic labeling and the diagnostic value of the derived volumes are improved with template sets based on brain atlases closely resembling the anatomy of the to‐be‐segmented brain magnetic resonance imaging scans.
Effectiveness of Continuous Passive Motion in an Inpatient Rehabilitation Hospital After Total Knee Replacement: A Matched Cohort Study
Authors: Herbold Janet Anne , Bonistall Kristen , Blackburn Marielle
Published: September 2012

Objective

To examine the use of continuous passive motion (CPM) as an adjunct to physical therapy after total knee replacement in patients who were transferred to an inpatient rehabilitation facility (IRF) and to compare the effectiveness of CPM on active range of motion (AROM), functional tasks, destination after discharge, the need for home care services, and the ambulation device at discharge.

Design

Matched cohort study.

Setting

IRF.

Participants

Patients admitted to a rehabilitation setting after total knee replacement surgery with an initial AROM for knee flexion of less than 75° at admission to the IRF. From this initial population, a matched sample of 61 patient pairs was included in the analysis (61 who used the CPM and 61 who did not receive the adjunct therapy).

Intervention

Use of CPM for 2 hours per day as an adjunct to the 3 hours of physical and occupational therapy customary in an IRF.

Main Outcomes

Primary outcomes were discharge active knee flexion ROM and flexion gain. Secondary outcomes were motor, cognitive, and total Functional Independence Measure scores; discharge ambulation device; destination after discharge; and the need for home care services after the inpatient stay.

Results

The outcome variables of 61 matched pairs of CPM users and non‐CPM users were reported. No statistically significant differences were found in any of the outcome variables that were compared in this matched case design, including AROM knee, flexion gain, discharge to the community, need for home care services after discharge, and discharge with cane/no device. No significant difference was found in all functional scores as measured by the Functional Independence Measure scale.

Conclusion

For this population, we determined at one facility that less than 30% are provided with a CPM as an adjunct to physical therapy. Using a matched cohort design, we compared CPM use with non‐CPM use and determined that the application of CPM may not significantly influence ROM gain.
Particle capture and low-Reynolds-number flow around a circular cylinder
Authors: Espinosa-Gayosso Alexis , Ghisalberti Marco , Ivey Gregory N. , Jones Nicole L.
Published: September 2012

Particle capture, whereby suspended particles contact and adhere to a solid surface (a ‘collector’), is an important mechanism in a range of environmental processes. In aquatic systems, typically characterized by low collector Reynolds numbers ($\mathit{Re}$), the rate of particle capture determines the efficiencies of a range of processes such as seagrass pollination, suspension feeding by corals and larval settlement. In this paper, we use direct numerical simulation (DNS) of a two-dimensional laminar flow to accurately quantify the rate of capture of low-inertia particles by a cylindrical collector for $\mathit{Re}\leq 47$ (i.e. a range where there is no vortex shedding). We investigate the dependence of both the capture rate and maximum capture angle on both the collector Reynolds number and the ratio of particle size to collector size. The inner asymptotic expansion of Skinner (Q. J. Mech. Appl. Maths, vol. 28, 1975, pp. 333–340) for flow around a cylinder is extended and shown to provide an excellent framework for the prediction of particle capture and flow close to the leading face of a cylinder up to $\mathit{Re}= 10$. Our results fill a gap between theory and experiment by providing, for the first time, predictive capability for particle capture by aquatic collectors in a wide (and relevant) Reynolds number and particle size range.
Borrowed Power: Debt Finance and the Resort to Arms
Authors: SLANTCHEV BRANISLAV L.
Published: September 2012

Military expenditures are often funded by debt, and sovereign borrowers are more likely to renege on debt-service obligations if they lose a war than if they win one or if peace prevails. This makes expected debt service costlier in peace, which can affect both crisis bargaining and war termination. I analyze a complete-information model where players negotiate in the shadow of power, whose distribution depends on their mobilization levels, which can be funded partially by borrowing. I show that players can incur debts that are unsustainable in peace because the opponent is unwilling to grant the concessions necessary to service them without fighting. This explanation for war is not driven by commitment problems or informational asymmetries but by the debt-induced inefficiency of peace relative to war. War results from actions that eliminate the bargaining range rather than from inability to locate mutually acceptable deals in that range.
Symplectic T7, T8 singularities and Lagrangian tangency orders
Authors: Domitrz Wojciech , Trȩbska Żaneta
Published: September 2012

We study the local symplectic algebra of curves. We use the method of algebraic restrictions to classify symplectic T7, T8 singularities. We define discrete symplectic invariants (the Lagrangian tangency orders) and compare them with the index of isotropy. We use these invariants to distinguish symplectic singularities of classical T7 singularity. We also give the geometric description of symplectic classes of the singularity.
The immune response to tuberculosis infection in the setting ofHelicobacter pyloriand helminth infections
Authors: PERRY S. , CHANG A. H. , SANCHEZ L. , YANG S. , HAGGERTY T. D. , PARSONNET J.
Published: September 2012

We screened 176 healthy, adult (aged 18–55 years) US refugees from tuberculosis (TB)-endemic countries to evaluate whether cytokine responses to latent TB infection (LTBI) are modified in the setting of concurrentH. pyloriand helminth infection. As measured by the Quantiferon-TB GOLD interferon-γ release assay, a total 38 (22%) subjects had LTBI, of which 28 (74%) also wereH. pyloriseropositive and/or helminth infected. Relative to ten subjects with LTBI only, 16 subjects with concurrentH. pyloriinfection had significantly elevated levels of IFN-γ, and nine subjects with bothH. pyloriand helminth infection had significantly elevated levels of IFN-γ, IL-2, IL-13, and IL-5.H. pyloriis associated with enhanced IFN-γ responses to TB, even in the setting of concurrent helminth infection. Efficacy of TB vaccines may vary with the co-existence of these three infections in the developing world.
Prevalence, risk factors and molecular epidemiology of methicillin-resistantStaphylococcus aureus(MRSA) colonization in residents of long-term care facilities in Luxembourg, 2010
Authors: MOSSONG J. , GELHAUSEN E. , DECRUYENAERE F. , DEVAUX A. , PERRIN M. , EVEN J. , HEISBOURG E.
Published: September 2012

A prevalence survey of methicillin-resistantStaphylococcus aureus(MRSA) was performed in 2010 in 19 long-term care facilities in Luxembourg. Of the 954 participating residents, 69 (7·2%) were colonized by MRSA. Previous history of MRSA [odds ratio (OR) 7·20, 95% confidence interval (CI) 3·19–16·27], quinolone therapy in the previous year (OR 2·27, 95% CI 1·17–4·41) and ⩾24 h care administered per week (OR 4·29, 95% CI 1·18–15·56) were independent risk factors for MRSA colonization. More than 75% of strains were of clonal complex (CC)5, mainlyspa-type t003 or sequence type (ST)225 and ST710, which is a rapidly emerging lineage prevalent in central Europe. Five residents were colonized by livestock-associated genotypes belonging to CC398. Previously dominant CC8 strains have recently been replaced by more resistant CC5 strains in Luxembourg.
THE CASE FOR DIVISIA MONEY TARGETING
Authors: Serletis Apostolos , Rahman Sajjadur
Published: September 2012

In this paper we investigate the relationship between money growth uncertainty and the level of economic activity in the United States. We pay explicit attention to the Divisia monetary aggregates. In doing so, we use the new vintage of the data [called MSI (monetary services indices) by the St. Louis Fed], together with the simple sum monetary aggregates, over the period from 1967:1 to 2011:3. In the context of a bivariate VARMA, GARCH-in-mean, asymmetric BEKK model, we show that increased Divisia money growth volatility (irrespective of the level of aggregation and the method of calculation) is associated with a lower average growth rate of real economic activity. However, there are no effects of simple-sum money growth volatility on real economic activity, except with the Sum M1 and perhaps Sum M2M aggregates. We conclude that monetary policies that focus on the Divisia monetary aggregates and target their growth rates will contribute to higher overall economic growth.
TNFα enhances TLR3‐dependent effects on MMP‐9 expression in human mesangial cells
Authors: Merkle Monika , Ribeiro Andrea , Köppel Simone , Wörnle Markus
Published: September 2012

The role of MMPs (matrix metalloproteinases) in kidney diseases has been widely accepted, where they can regulate inflammatory response because of their effects on both recruitment and survival of inflammatory cells. TNFα (tumour necrosis factor α) has also been implicated in the pathogenesis of inflammatory kidney diseases, including forms of glomerulonephritis associated with viral diseases. Previously, we established the functional linkage between viral receptors of the innate immune system, the TLRs (Toll‐like receptors) and control of MMP activity in human MC (mesangial cells). Expression levels of MMP‐2, MMP‐7, MMP‐9, TIMP‐1 (tissue inhibitor of metalloproteinase 1) and TIMP‐2 in human MC in culture were analysed by RT‐PCR (reverse transcription–PCR). TNFα significantly enhanced the TLR3‐dependent induction of MMP‐9 in human MC. Expression levels of MMP‐2, TIMP‐1 and TIMP‐2 were not significantly affected by the activation of TLR3 or TNFα stimulation. No significant MMP‐7 expression was found. We conclude that the role of MMP‐9 in chemotaxis, activation and proliferation of inflammatory cells is amplified by TNFα originating from infiltrating cells, especially monocytes, producing a regulatory loop that potentially leads to a self‐propagating inflammation.
Endothelium‐dependent vascular smooth muscle relaxation activated by electrical field stimulation
Authors: GEARY G. G . , MAEDA G. , GONZALEZ JR R. R.
Published: September 2012

Electrical field stimulation (EFS) produced relaxation of contracted arteries in the presence of tetrodotoxin. In the present study the contributions of vascular smooth muscle repolarization and endothelial release of nitric oxide to the relaxation response were investigated using isolated rat tail arteries and bovine aortic endothelial cells (BAEC). Intact and endothelium‐denuded rings or intact, pressurized artery segments were contracted with either phenylephrine or KCl prior to EFS. Electrical field stimulation induced a small relaxation in denuded, phenylephrine contracted rings that was inhibited by the K+ channel blockers glibenclamide and BaCl2 In intact, phenylephrine‐contracted rings, EFS induced significantly larger relaxations that were inhibited by BaCl2 as well as by LNAME, an inhibitor of nitric oxide (NO) synthase, and methylene blue. EFS‐induced relaxations were completely inhibited when BaCl2 and L‐NAME or methylene blue were combined. Exposure to Ca2+‐
free buffer or diltiazem also inhibited the relaxation while ascorbic acid had no effect. Effluent from electrically stimulated BAEC caused denuded, phenylephrine contracted rings to relax. The ability of
the effluent to cause relaxation was almost completely blocked by exposure of the BAEC to L‐NAME or exposure of the recipient vascular smooth muscle to methylene blue; glibenclamide caused partial blockade. Simultaneous measurements of membrane potential and intraluminal pressure showed that EFS‐induced membrane repolarization preceded changes in steady‐state pressure. It is concluded that (1) the smooth muscle cells possess an endothelium‐independent repolarization mechanism, (2) EFS causes endothelial cells of intact arteries to release NO and possibly a hyperpolarizing factor, (3) EFS of BAEC causes release of NO, and (4) EFS‐induced relaxation depends on vascular smooth muscle cell membrane repolarization and endothelial cell release of vasoactive substances.
Adenosine triphosphate treatment for meconium aspiration‐induced pulmonary hypertension in pigs
Authors: Kääpä P. , JAHNUKAINEN T. , GRÖNLUND J. , RAUTANEN M. , HALKOLA L. , VÄLIMÄKI I.
Published: September 2012

To investigate the pulmonary haemodynamic effects of meconium aspiration and subsequent adenosine triphosphate (ATP) treatment, 12 anaesthetized and ventilated pigs (wt 24‐28 kg) received either ATP or an equal volume of saline into the right heart in doses of 0.02 to 0.80 lmol kg‐1 min−1 after intratracheal administration of 2 mL kg−1 of human meconium.
Meconium instillation induced significant increases in pulmonary vascular pressures and total and postarterial resistances calculated from pulmonary artery occlusion studies, but did not affect
the systemic haemodynamics, except for a fall in heart rate and increase in central venous pressure. Infusion of ATP at the lowest doses (0.02 and 0.08 µmol kg−1 min−1) selectively
decreased the pulmonary arterial pressure and vascular resistance and at 0.32 and 0.80 µmol kg−1 min−1 reduced both the pulmonary and systemic resistances. In the lung circulation the increasing doses of ATP reduced preferably the arterial, but also the postarterial resistance. Withdrawal of ATP infusion led to a significant rebound effect especially in the postarterial segment of the lung circulation. Meconium aspiration thus induces an acute, predominantly postarterial obstruction in the lung circulation and infusion of ATP at low doses selectively dilates the pulmonary vascular bed and may help to preclude elevation of capillary pressures in meconium aspiration‐induced pulmonary hypertension.
Mean-field theory of the phase diagram of ultrasoft, oppositely charged polyions in solution
Authors: Nikoubashman Arash , Hansen Jean-Pierre , Kahl Gerhard
Published: September 2012

We investigate the phase separation of the “ultrasoft restricted primitive model” (URPM), a coarse-grained representation of oppositely charged, interpenetrating polyelectrolytes, within a mean-field description based on the “chemical picture.” The latter distinguishes between free ions and dimers of oppositely charged ions (Bjerrum pairs) which are in chemical equilibrium governed by a law of mass action. Interactions between ions, and between ions and dimers are treated within linearized Poisson-Boltzmann theory, at four levels of approximation corresponding to increasingly refined descriptions of the interactions. The URPM is found to phase separate into a dilute phase of dimers, and a concentrated phase of mostly free (unpaired) ions below a critical temperature Tc. The phase diagram differs, however, considerably from the predictions of recent simulations; Tc is about three times higher, and the critical density is much lower than the corresponding simulation data [D. Coslovich, J. P. Hansen, and G. Kahl, Soft Matter 7, 1690 (2011)10.1039/c0sm01090a]. Possible reasons for this unexpected failure of mean-field theory are discussed. The Kirkwood line, separating the regimes of monotonically decaying and damped oscillatory decay of the charge-charge correlation function at large distances is determined within the random phase approximation.
Kinetic theory of magnetized dusty plasmas with dust particles charged by collisional processes and by photoionization
Authors: Galvão R. A. , Ziebell L. F.
Published: September 2012

In this work, we detail the derivation of a plasma kinetic theory leading to the components of the dielectric tensor for a magnetized dusty plasma with variable charge on the dust particles, considering that the dust component of the plasma contains spherical dust particles with different sizes, which are charged both by inelastic collisions of electrons and ions and by photoionization.
Micro-structure evolution of wall based crystals after casting of model suspensions as obtained from Bragg microscopy
Authors: Palberg Thomas , Maaroufi Martin R. , Stipp Andreas , Schöpe Hans Joachim
Published: September 2012

Growth of heterogeneously nucleated, wall based crystals plays a major role in determining the micro-structure during melt casting. This issue is here addressed using a model system of charged colloidal spheres in deionized aqueous suspension observed by Bragg microscopy which is a combination of light scattering and microscopy. We examine the evolution of the three-dimensional size, shape, and orientation of twin domains in monolithic crystals growing from two opposing planar walls into a meta-stable (shear-) melt. At each wall crystal orientation and twinning emerges during nucleation with small domains. During growth these widen and merge. From image analysis we observe the lateral coarsening velocities to follow a power law behaviour LXY ∝ t1/2 as long as the vertical growth continues at constant speed. Lateral coarsening terminates upon intersection of the two solids and hardly any further ripening is seen. Initial lateral coarsening velocities show a Wilson Frenkel type dependence on the melt meta-stability.
Effect of grafting on nanoparticle segregation in polymer/nanoparticle blends near a substrate
Authors: Padmanabhan Venkat
Published: September 2012

Nanoparticles in polymer films have shown the tendency to migrate to the substrate due to an entropic-based attractive depletion interaction between the particles and the substrate. It is also known that polymer-grafted nanoparticles show better dispersion in a polymer matrix. Here, molecular dynamics simulations are employed to study the effect of grafting on the nanoparticle segregation to the substrate. The nanoparticles were modeled as spheres and the polymers as bead-spring chains. The polymers of the grafts and the matrix are identical in nature. For a purely repulsive system, the nanoparticle density near the surface was found to decrease as the length of grafted chains and the number of grafts increased and in the bulk, the nanoparticles are well-dispersed. Whereas, in case of attractive systems with interparticle interactions on the order of thermal energy, the nanoparticles segregated to the substrate even more strongly, essentially forming clusters on the wall and in the bulk. However, due to the presence of grafted chains on the nanoparticles, the clusters formed in the bulk are structurally anisotropic. The effect of grafts on nanoparticle segregation to the surface was found to be qualitatively similar to the purely repulsive case.
Radiowave dielectric investigation of water confined in channels of carbon nanotubes
Authors: Cametti C. , De Luca F. , Parmentier A.
Published: September 2012

Structure and dynamics of water confined in channels of diameter of few nanometer in size strongly differ from the ones of water in the bulk phase. Here, we present radiowave dielectric relaxation measurements on water-filled single-walled carbon nanotubes, with the aim of highlighting some aspects on the molecular electric dipole organization of water responding to high spatial confinement in a hydrophobic environment. The observed dielectric spectra, resulting into two contiguous relaxation processes, allow us to separate the confined water in the interior of the nanotubes from external water, providing support for the existence in the confinement region of water domains held together by hydrogen bonds. Our results, based on the deconvolution of the dielectric spectra due to the presence of a bulk and a confined water phase, furnish a significantly higher Kirkwood correlation factor, larger than the one of water in bulk phase, indicating a strong correlation between water molecules inside nanotubes, not seen in bulk water.
Thomson-resonant interference effects in elastic x-ray scattering near the Cl K edge of HCl
Authors: Carniato S. , Selles P. , Journel L. , Guillemin R. , Stolte W. C. , El Khoury L. , Marin T. , Gel'mukhanov F. , Lindle D. W. , Simon M.
Published: September 2012

We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl K edge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions.
Effect of strain on critical magnetic field in type-II superconductors
Authors: He An , Yong Huadong , Xue Cun , Zhou Youhe
Published: September 2012

The strain effect on critical magnetic field in isotropic high-κ superconductors is studied theoretically in this paper. Based on the phenomenological theory, we obtain the critical magnetic field in the presence of the applied strain. The dependence of upper critical magnetic field on the coupling parameters is discussed. The theoretical analysis is in broad agreement with experimental results as the coupling parameters are the linear functions of the strain. Furthermore, according to the assumption, the plot of strain effect on lower critical field is observed as symmetric curve for compressive and tensile strains. The plots also predict that the strain effect on lower critical field is greater in higher-κ superconductors.
Flux pinning and magnetic relaxation in Ga-doped LiFeAs single crystals
Authors: Shlyk L. , Bischoff M. , Rose E. , Niewa R.
Published: September 2012

The effect of nonmagnetic Ga3+ impurities on structural and superconducting properties of LiFeAs single crystals has been studied. The out-of-plane magnetization of the doped material exhibits a remarkable double-peak structure. The presence of a low-field peak observed both in doped and undoped LiFeAs is suggestive of intrinsic structural defects, while a secondary high-field fishtail maximum, which shifts progressively with temperature, is associated with the extrinsic pinning centers created by Ga. The superconducting transition temperature of Ga doped LiFeAs is suppressed by about 4.8 K/at. %. However, a set of superconducting parameters including the superconducting transition temperature, the coherence length, the upper critical field, and the irreversibility field are not significantly reduced in a sample doped with 0.5 at. % Ga. At this Ga concentration, the critical current density of doped LiFeAs is about four times that of our undoped material in intermediate magnetic fields at 5 K. The scaling of the normalized pinning force density Fp = JcB vs the applied field normalized by Bmax (Bmax denotes the peak position of Fpmax) in the temperature range 5–13 K indicates a single type of predominant flux-pinning mechanism provided by Ga additions. Analysis of the temperature and field dependencies of the magnetic relaxation is consistent with the collective pinning model. The magnetic relaxation measurements combined with the peak position of the critical current density in the B-T phase diagram suggests an elastic–plastic transition of the vortex lattice at higher temperatures and fields. The observed vortex behavior of Ga doped LiFeAs strongly resembles that of YBa2Cu3O7 doped with nonmagnetic impurities.
The drag force on a subsonic projectile in a fluid complex plasma
Authors: Ivlev A. V. , Zhukhovitskii D. I.
Published: September 2012

The incompressible Navier-Stokes equation is employed to describe a subsonic particle flow induced in complex plasmas by a moving projectile. Drag forces acting on the projectile in different flow regimes are calculated. It is shown that, along with the regular neutral gas drag, there is an additional force exerted on the projectile due to dissipation in the surrounding particle fluid. This additional force provides significant contribution to the total drag.
Note: A versatile, stable, high-resolution readout system for RTD and thermistor sensors
Authors: Ambrosetti R. , Matteoli E. , Ricci D.
Published: September 2012

A readout system for resistance temperature detectors and thermistors is described featuring temperature resolution better than 1 mK and capability to fit sensors having different resistance or requiring different excitation current. For instance, with a sensor equivalent to an ideal 100 Ω Pt, an excitation current of 0.7 mA, and reading @ 1Hz, the system resolution corresponds to 0.38 mK and its temperature coefficient (TC) to 0.26 mK/K. The system, however, can control its own temperature accurately enough to make its TC negligible. When thermostated, the overall stability of the system was better than 10 ppm for 230 h.
One-Pot Endgroup-Modification of Hydrophobic RAFT Polymers with Cyclodextrin by Thiol-ene Chemistry and the Subsequent Formation of Dynamic Core–Shell Nanoparticles Using Supramolecular Host–Guest Chemistry
Authors: Yhaya Firdaus , Binauld Sandra , Callari Manuela , Stenzel Martina H.
Published: September 2012

Poly(methyl methacrylate) PMMA, synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization, was heated in a solvent at 100°C for 24 h leading to the loss of the RAFT endfunctionality and the complete conversion into a vinyl group. Mono(6-deoxy-6-mercapto)-β-cyclodextrin (β-CD-SH) was subsequently clicked onto the polymer by a thiol-ene reaction leading to PMMA with one β-CD as a terminal group (PMMA70–β-CD). Meanwhile, a RAFT agent with an adamantyl group has been prepared for the polymerization of 2-hydroxyethyl acrylate (HEA) leading to PHEA95–Ada. Two processes were employed to generate core–shell nanoparticles from these two polymers: a one-step approach that employs a solution of both polymers at stoichiometric amounts in DMF, followed by the addition of water, and a two step process that uses PMMA solid particles with surface enriched with β-CD in water, which have a strong tendency to aggregate, followed by the addition of PHEA95–Ada in water. Both pathways led to stable core–shell nanoparticles of ~150 nm in size. Addition of free β-CD competed with the polymer bound β-CD releasing the PHEA hairs from the particle surface. As a result, the PMMA particles started agglomerating resulting in a cloudy solution. A similar effect was observed when heating the solution. Since the equilibrium constant between β-CD and adamantane decreases with increasing temperature, the stabilizing PHEA chains cleaved from the surface and the solution turned cloudy due to the aggregation of the naked PMMA spheres. This process was reversible and with decreasing temperature the core–shell nanoparticles formed again leading to a clear solution.
On the Origins of Nitroxide Mediated Polymerization (NMP) and Reversible Addition–Fragmentation Chain Transfer (RAFT)
Authors: Rizzardo Ezio , Solomon David H.
Published: September 2012

The early experiments on radical polymerization, which were to lead to a study of nitroxide trapping of the initiation step and the interest in defect groups, particularly the macromonomers formed by termination by disproportionation, are discussed. Results from the nitroxide trapping clearly show that the initiation step ranges from simple clean addition to the head of the monomer, to complex addition/abstraction reactions. Careful selection of the monomer/initiation system is emphasized with particular reference to two common monomers, styrene and methyl methacrylate, and two initiating radicals, t-butoxy and benzoyloxy. The discovery of nitroxide mediated polymerization (NMP) from observations made during the nitroxide trapping work is reported and the ability to have a living radical system demonstrated with numerous examples. Similarly, the study of the copolymerization of macromonomers, formed by disproportionation of the propagating chains, is discussed with the discovery of β-scission and an early form of addition–fragmentation reported. The evolution of reversible addition–fragmentation chain transfer (RAFT) to a highly versatile and commercially attractive radical system is reported and the detailed chemistry behind the discovery of this living radical system discussed. Both NMP and RAFT enable the synthesis of structures not previously possible by radical polymerization and in some cases not possible by any other process.
Mechanism for Hypocretin-mediated sleep-to-wake transitions
Authors: Carter Matthew E. , Brill Julia , Bonnavion Patricia , Huguenard John R. , Huerta Ramon , de Lecea Luis
Published: September 2012

Current models of sleep/wake regulation posit that Hypocretin (Hcrt)-expressing neurons in the lateral hypothalamus promote and stabilize wakefulness by projecting to subcortical arousal centers. However, the critical downstream effectors of Hcrt neurons are unknown. Here we use optogenetic, pharmacological, and computational tools to investigate the functional connectivity between Hcrt neurons and downstream noradrenergic neurons in the locus coeruleus (LC) during nonrapid eye movement (NREM) sleep. We found that photoinhibiting LC neurons during Hcrt stimulation blocked Hcrt-mediated sleep-to-wake transitions. In contrast, when LC neurons were optically stimulated to increase membrane excitability, concomitant photostimulation of Hcrt neurons significantly increased the probability of sleep-to-wake transitions compared with Hcrt stimulation alone. We also built a conductance-based computational model of Hcrt-LC circuitry that recapitulates our behavioral results using LC neurons as the main effectors of Hcrt signaling. These results establish the Hcrt-LC connection as a critical integrator-effector circuit that regulates NREM sleep/wake behavior during the inactive period. This coupling of distinct neuronal systems can be generalized to other hypothalamic integrator nuclei with downstream effector/output populations in the brain.
Microbial shifts in the swine distal gut in response to the treatment with antimicrobial growth promoter, tylosin
Authors: Kim Hyeun Bum , Borewicz Klaudyna , White Bryan A. , Singer Randall S. , Sreevatsan Srinand , Tu Zheng Jin , Isaacson Richard E.
Published: September 2012

Antimicrobials have been used extensively as growth promoters (AGPs) in agricultural animal production. However, the specific mechanism of action for AGPs has not yet been determined. The work presented here was to determine and characterize the microbiome of pigs receiving one AGP, tylosin, compared with untreated pigs. We hypothesized that AGPs exerted their growth promoting effect by altering gut microbial population composition. We determined the fecal microbiome of pigs receiving tylosin compared with untreated pigs using pyrosequencing of 16S rRNA gene libraries. The data showed microbial population shifts representing both microbial succession and changes in response to the use of tylosin. Quantitative and qualitative analyses of sequences showed that tylosin caused microbial population shifts in both abundant and less abundant species. Our results established a baseline upon which mechanisms of AGPs in regulation of health and growth of animals can be investigated. Furthermore, the data will aid in the identification of alternative strategies to improve animal health and consequently production.
Personal Protective Equipment Management and Policies: European Network for Highly Infectious Diseases Data from 48 Isolation Facilities in 16 European Countries
Authors: Iaco Giuseppina De , Puro Vincenzo , Fusco Francesco Maria , Schilling Stefan , Maltezou Helena C. , Brouqui Philippe , Gottschalk René , Bannister Barbara , Brodt Hans-Reinhard , Siikamaki Heli , Perronne Christian , Brantsæter Arne Broch , Fjellet Anne Lise , Ippolito Giuseppe ,   European Network for Highly Infectious Diseases Working Group
Published: September 2012

Objective.

To collect data about personal protective equipment (PPE) management and to provide indications for improving PPE policies in Europe.

Design.

Descriptive, cross-sectional survey.

Setting and Participants.

Data were collected in 48 isolation facilities in 16 European countries nominated by National Health Authorities for the management of highly infectious diseases (HIDs).

Methods.

Data were collected through standardized checklists at on-site visits during February-November 2009. Indications for adequate PPE policies were developed on the basis of a literature review, partners' expert opinions, and the collected data.

Results.

All facilities have procedures for the selection of PPE in case of HID, and 44 have procedures for the removal of PPE. In 40 facilities, different levels of PPE are used according to a risk assessment process, and in 8 facilities, high-level PPE (eg, positive-pressure complete suits or Trexler units) is always used. A fit test is performed at 25 of the 40 facilities at which it is applicable, a seal check is recommended at 25, and both procedures are used at 17. Strategies for promoting and monitoring the correct use of PPE are available at 42 facilities. In case of a sudden increase in demand, 44 facilities have procedures for rapid supply of PPE, whereas 14 facilities have procedures for decontamination and reuse of some PPE.

Conclusions.

Most isolation facilities devote an acceptable level of attention to PPE selection and removal, strategies for the promotion of the correct use of PPE, and ensuring adequate supplies of PPE. Fit test and seal check procedures are still not widely practiced. Moreover, policies vary widely between and within European countries, and the development of common practice procedures is advisable.

Infect Control Hosp Epidemiol2012;33(10):1008-1016
Daily Disinfection of High-Touch Surfaces in Isolation Rooms to Reduce Contamination of Healthcare Workers' Hands
Authors: Kundrapu Sirisha , Sunkesula Venkata , Jury Lucy A. , Sitzlar Brett M. , Donskey Curtis J.
Published: September 2012

In a randomized nonblinded trial, we demonstrated that daily disinfection of high-touch surfaces in rooms of patients with Clostridium difficile infection and methicillin-resistant Staphylococcus aureus colonization reduced acquisition of the pathogens on hands after contacting high-touch surfaces and reduced contamination of hands of healthcare workers caring for the patients.

Infect Control Hosp Epidemiol 2012;33(10):1039-1042
Epidemiology and Healthcare Costs of Incident Clostridium difficile Infections Identified in the Outpatient Healthcare Setting
Authors: Kuntz Jennifer L. , Johnson Eric S. , Raebel Marsha A. , Petrik Amanda F. , Yang Xiuhai , Thorp Micah L. , Spindel Steven J. , Neil Nancy , Smith David H.
Published: September 2012

Objective.

To describe the epidemiology and healthcare costs of Clostridium difficile infection (CDI) identified in the outpatient setting.

Design.

Population-based, retrospective cohort study.

Patients.

Kaiser Permanente Colorado and Kaiser Permanente Northwest members between June 1, 2005, and September 30, 2008.

Methods.

We identified persons with incident CDI and classified CDI by whether it was identified in the outpatient or inpatient healthcare setting. We collected information about baseline variables and follow-up healthcare utilization, costs, and outcomes among patients with CDI. We compared characteristics of patients with CDI identified in the outpatient versus inpatient setting.

Results.

We identified 3,067 incident CDIs; 56% were identified in the outpatient setting. Few strong, independent predictors of diagnostic setting were identified, although a previous stay in a nonacute healthcare institution (odds ratio [OR], 1.45 [95% confidence interval (CI), 1.13-1.86]) was statistically associated with outpatient-identified CDI, as was age from 50 to 59 years (OR, 1.64 [95% CI, 1.18-2.29]), 60 to 69 years (OR, 1.37 [95% CI, 1.03-1.82]), and 70 to 79 years (OR, 1.36 [95% CI, 1.06-1.74]), when compared with persons aged 80-89 years.

Conclusions.

We found that more than one-half of incident CDIs in this population were identified in the outpatient setting. Patients with outpatient-identified CDI were younger with fewer comorbidities, although they frequently had previous exposure to healthcare. These data suggest that practitioners should be aware of CDI and obtain appropriate diagnostic testing on outpatients with CDI symptoms.

Infect Control Hosp Epidemiol 2012;33(10):1031-1038
Active Surveillance and Decolonization of Methicillin-Resistant Staphylococcus aureus on Admission to Neonatal Intensive Care Units in Hong Kong: A Cost-Effectiveness Analysis
Authors: You Joyce H. S. , Chan C. Y. , Wong M. Y. , Ip Margaret
Published: September 2012

Objective.

To examine potential clinical outcomes and cost of active methicillin-resistant Staphylococcus aureus (MRSA) surveillance with and without decolonization in neonatal intensive care units (NICUs) from the perspective of healthcare providers in Hong Kong.

Design.

Decision analysis modeling.

Setting.

NICU.

Patients.

Hypothetical cohort of patients admitted to an NICU.

Methods.

We designed a decision tree to simulate potential outcomes of active MRSA surveillance with and without decolonization in patients admitted to an NICU. Outcome measures included total direct medical cost per patient, MRSA infection rate, and MRSA-associated mortality rate. Model inputs were derived from the literature. Sensitivity analyses evaluated the impact of uncertainty in all model variables.

Results.

In the base-case analysis, active surveillance plus decolonization showed a lower expected MRSA infection rate (0.911% vs 1.759%), MRSA-associated mortality rate (0.223% vs 0.431%), and total cost per patient (USD 47,294 vs USD 48,031) compared with active surveillance alone. Sensitivity analyses showed that active surveillance plus decolonization cost less and had lower event rates if the incidence risk ratio of acquiring MRSA infections in carriers after decolonization was less than 0.997. In 10,000 Monte Carlo simulations, active surveillance plus decolonization was significantly less costly than active surveillance alone 99.9% of the time, and both the MRSA infection rate and the MRSA-associated mortality rate were significantly lower 99.9% of the time.

Conclusions.

Active surveillance plus decolonization for patients admitted to NICUs appears to be cost saving and effective in reducing the MRSA infection rate and the MRSA-associated mortality rate if addition of decolonization to active surveillance reduces the risk of MRSA infection.

Infect Control Hosp Epidemiol 2012;33(10):1024-1030
A note on the moments of Kloosterman sums
Authors: Xi Ping , Yi Yuan
Published: September 2012

In this note, we deduce an asymptotic formula for even power moments of Kloosterman sums based on the important work of N. M. Katz on Kloosterman sheaves. In a similar manner, we can also obtain an upper bound for odd power moments. Moreover, we shall give an asymptotic formula for odd power moments of absolute Kloosterman sums. Consequently, we find that there are infinitely many

a
mod
p

a\bmod p

such that

S
(
a
,
1
;
p
)
≷
0

S(a,1;p)\gtrless 0

as

p
→
+
∞
.

p\rightarrow +\infty .
The Hog1 SAPK controls the Rtg1/Rtg3 transcriptional complex activity by multiple regulatory mechanisms
Authors: Ruiz-Roig Clàudia , Noriega Núria , Duch Alba , Posas Francesc , de Nadal Eulàlia
Published: September 2012

Cells modulate expression of nuclear genes in response to alterations in mitochondrial function, a response termed retrograde (RTG) regulation. In budding yeast, the RTG pathway relies on Rtg1 and Rtg3 basic helix-loop-helix leucine Zipper transcription factors. Exposure of yeast to external hyperosmolarity activates the Hog1 stress-activated protein kinase (SAPK), which is a key player in the regulation of gene expression upon stress. Several transcription factors, including Sko1, Hot1, the redundant Msn2 and Msn4, and Smp1, have been shown to be directly controlled by the Hog1 SAPK. The mechanisms by which Hog1 regulates their activity differ from one to another. In this paper, we show that Rtg1 and Rtg3 transcription factors are new targets of the Hog1 SAPK. In response to osmostress, RTG-dependent genes are induced in a Hog1-dependent manner, and Hog1 is required for Rtg1/3 complex nuclear accumulation. In addition, Hog1 activity regulates Rtg1/3 binding to chromatin and transcriptional activity. Therefore Hog1 modulates Rtg1/3 complex activity by multiple mechanisms in response to stress. Overall our data suggest that Hog1, through activation of the RTG pathway, contributes to ensure mitochondrial function as part of the Hog1-mediated osmoadaptive response.
The methyltransferase adaptor protein Trm112 is involved in biogenesis of both ribosomal subunits
Authors: Sardana Richa , Johnson Arlen W.
Published: September 2012

We previously identified Bud23 as the methyltransferase that methylates G1575 of rRNA in the P-site of the small (40S) ribosomal subunit. In this paper, we show that Bud23 requires the methyltransferase adaptor protein Trm112 for stability in vivo. Deletion of Trm112 results in a bud23Δ-like mutant phenotype. Thus Trm112 is required for efficient small-subunit biogenesis. Genetic analysis suggests the slow growth of a trm112Δ mutant is due primarily to the loss of Bud23. Surprisingly, suppression of the bud23Δ-dependent 40S defect revealed a large (60S) biogenesis defect in a trm112Δ mutant. Using sucrose gradient sedimentation analysis and coimmunoprecipitation, we show that Trm112 is also involved in 60S subunit biogenesis. The 60S defect may be dependent on Nop2 and Rcm1, two additional Trm112 interactors that we identify. Our work extends the known range of Trm112 function from modification of tRNAs and translation factors to both ribosomal subunits, showing that its effects span all aspects of the translation machinery. Although Trm112 is required for Bud23 stability, our results suggest that Trm112 is not maintained in a stable complex with Bud23. We suggest that Trm112 stabilizes its free methyltransferase partners not engaged with substrate and/or helps to deliver its methyltransferase partners to their substrates.