724 research outputs found
Heat-kernel expansion and counterterms of the Faddeev-Popov determinant in Coulomb and Landau gauge
The Faddeev-Popov determinant of Landau gauge in d dimensions and Coulomb
gauge in d+1 dimensions is calculated in the heat-kernel expansion up to
next-to-leading order. The UV-divergent parts in d=3,4 are isolated and the
counterterms required for a non-perturbative treatment of the Faddeev-Popov
determinant are determined.Comment: 7 page
Quantum field theory of metallic spin glasses
We introduce an effective field theory for the vicinity of a zero temperature
quantum transition between a metallic spin glass (``spin density glass'') and a
metallic quantum paramagnet. Following a mean field analysis, we perform a
perturbative renormalization-group study and find that the critical properties
are dominated by static disorder-induced fluctuations, and that dynamic
quantum-mechanical effects are dangerously irrelevant. A Gaussian fixed point
is stable for a finite range of couplings for spatial dimensionality ,
but disorder effects always lead to runaway flows to strong coupling for . Scaling hypotheses for a {\em static\/} strong-coupling critical field
theory are proposed. The non-linear susceptibility has an anomalously weak
singularity at such a critical point. Although motivated by a perturbative
study of metallic spin glasses, the scaling hypotheses are more general, and
could apply to other quantum spin glass to paramagnet transitions.Comment: 16 pages, REVTEX 3.0, 2 postscript figures; version contains
reference to related work in cond-mat/950412
Effect of Pre- and In-Hospital Delay on Reperfusion in Acute Ischemic Stroke Mechanical Thrombectomy.
Post hoc analyses of randomized controlled clinical trials evaluating mechanical thrombectomy have suggested that admission-to-groin-puncture (ATG) delays are associated with reduced reperfusion rates. Purpose of this analysis was to validate this association in a real-world cohort and to find associated factors and confounders for prolonged ATG intervals.
Patients included into the BEYOND-SWIFT cohort (Bernese-European Registry for Ischemic Stroke Patients Treated Outside Current Guidelines With Neurothrombectomy Devices Using the Solitaire FR With the Intention for Thrombectomy; https://www.clinicaltrials.gov; Unique identifier: NCT03496064) were analyzed (n=2386). Association between baseline characteristics and ATG was evaluated using mixed linear regression analysis. The effect of increasing symptom-onset-to-admission and ATG intervals on successful reperfusion (defined as Thrombolysis in Cerebral Infarction [TICI] 2b-3) was evaluated using logistic regression analysis adjusting for potential confounders.
Median ATG was 73 minutes. Prolonged ATG intervals were associated with the use of magnetic resonance imaging (+19.1 [95% CI, +9.1 to +29.1] minutes), general anesthesia (+12.1 [95% CI, +3.7 to +20.4] minutes), and borderline indication criteria, such as lower National Institutes of Health Stroke Scale, late presentations, or not meeting top-tier early time window eligibility criteria (+13.8 [95% CI, +6.1 to +21.6] minutes). There was a 13% relative odds reduction for TICI 2b-3 (adjusted odds ratio [aOR], 0.87 [95% CI, 0.79-0.96]) and TICI 2c/3 (aOR, 0.87 [95% CI, 0.79-0.95]) per hour ATG delay, while the reduction of TICI 2b-3 per hour increase symptom-onset-to-admission was minor (aOR, 0.97 [95% CI, 0.94-0.99]) and inconsistent regarding TICI 2c/3 (aOR, 0.99 [95% CI, 0.97-1.02]). After adjusting for identified factors associated with prolonged ATG intervals, the association of ATG delay and lower rates of TICI 2b-3 remained tangible (aOR, 0.87 [95% CI, 0.76-0.99]).
There is a great potential to reduce ATG, and potential targets for improvement can be deduced from observational data. The association between in-hospital delay and reduced reperfusion rates is evident in real-world clinical data, underscoring the need to optimize in-hospital workflows. Given the only minor association between symptom-onset-to-admission intervals and reperfusion rates, the causal relationship of this association warrants further research. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03496064
NMR and NQR Fluctuation Effects in Layered Superconductors
We study the effect of thermal fluctuations of the s-wave order parameter of
a quasi two dimensional superconductor on the nuclear spin relaxation rate near
the transition temperature Tc. We consider both the effects of the amplitude
fluctuations and the Berezinskii-Kosterlitz-Thouless (BKT) phase fluctuations
in weakly coupled layered superconductors. In the treatment of the amplitude
fluctuations we employ the Gaussian approximation and evaluate the longitudinal
relaxation rate 1/T1 for a clean s-wave superconductor, with and without pair
breaking effects, using the static pair fluctuation propagator D. The increase
in 1/T1 due to pair breaking in D is overcompensated by the decrease arising
from the single particle Green's functions. The result is a strong effect on
1/T1 for even a small amount of pair breaking. The phase fluctuations are
described in terms of dynamical BKT excitations in the form of pancake
vortex-antivortex (VA) pairs. We calculate the effect of the magnetic field
fluctuations caused by the translational motion of VA excitations on 1/T1 and
on the transverse relaxation rate 1/T2 on both sides of the BKT transitation
temperature T(BKT)<Tc. The results for the NQR relaxation rates depend strongly
on the diffusion constant that governs the motion of free and bound vortices as
well as the annihilation of VA pairs. We discuss the relaxation rates for real
multilayer systems where the diffusion constant can be small and thus increase
the lifetime of a VA pair, leading to an enhancement of the rates. We also
discuss in some detail the experimental feasibility of observing the effects of
amplitude fluctuations in layered s-wave superconductors such as the
dichalcogenides and the effects of phase fluctuations in s- or d-wave
superconductors such as the layered cuprates.Comment: 38 pages, 12 figure
Strategic Environmental Assessment and Sustainability in Europe - How Bright is the Future?
Improved detection by next-generation sequencing of pyrazinamide resistance in mycobacterium tuberculosis isolates
Technical limitations of common tests used for detecting pyrazinamide (PZA) resistance in
Mycobacterium tuberculosis (MTB) isolates pose challenges for comprehensive and accurate
descriptions of drug resistance in patients with multi-drug resistant tuberculosis (MDR-TB) . In
this study, a 606 base pair fragment (comprising the pncA coding region plus promoter) was
sequenced using Ion Torrent next generation sequencing (NGS) for detecting associated PZA
resistance mutations in 90 re-cultured, MDR-TB isolates from an archived series collected in
2001. These 90 isolates were previously Sanger sequenced, with 55 (62%) designated as carrying
wild type pncA gene and 33 (38%) showing mutations. Also earlier, PZA susceptibility of the isolates was determined using the Bactec 460 TB system and the Wayne test. In this study,
isolates were re-cultured and susceptibility testing performed in Bactec 960 MGIT. Concordance
between NGS and MGIT results was 87% (n = 90), and with the Bactec 460, Wayne test, and
pncA gene Sanger sequencing, 82% (n = 88), 83% (n = 88), and 89% (n = 88), respectively.
NGS confirmed the majority of pncA mutations detected by Sanger sequencing, but revealed
several new and mixed-strain mutations that resolved discordancy in other phenotypic results.
Importantly, in 53% (18/34) of these isolates, pncA mutations were located in the 151-360
region, and warrants further exploration. In these isolates, with known resistance to rifampicin,
NGS of pncA improved PZA resistance detection sensitivity to 97% and specificity to 94% using
NGS as the gold standard, and helped to resolve discordant results from conventional
methodologies.University of Pretoria, the South African Medical Research Council, and the National Research Foundation of South Africa.http://jcm.asm.org2016-06-30hb201
Next-generation sequencing for identifying pyrazinamide resistance in Mycobacterium tuberculosis
No abstract available.http://cid.oxfordjournals.orgam201
Location, location, location: contextualizing workplace commitment
The purpose of the present commentary is to discuss the nature and correlates of workplace commitment across cultures. We asked six organizational behavior scholars, who are intimately familiar with Brazil, China, Denmark, Germany, or Israel as their country of origin or extended residence, to “contextualize” workplace commitment. They did so by explicating institutional and cultural characteristics of their context on the emergence, meaning, and evolution of commitment by reference to their own research and extant local research. Their responses not only supported the utility of three-component model of commitment but also revealed the differential salience of various commitment constructs (e.g., components and foci of commitment) as well as possible contextual moderators on the development and outcomes of commitment. The commentators also described changes including the growing prevalence of multicultural workforces within national borders and changes in employment relationships and cultural values in their national contexts and considered future research directions in culture and commitment research
Opsonic monoclonal antibodies enhance phagocytic killing activity and clearance of Mycobacterium tuberculosis from blood in a quantitative qPCR mouse model
BACKGROUND : Patients with impaired immunity often have rapid progression of tuberculosis (TB) which can lead to
highly lethal Mycobacterium tuberculosis (MTB) sepsis. Opsonic monoclonal antibodies (MABs) directed against
MTB that enhance phagocytic killing activity and clearance of MTB from blood may be useful to enhance TB
immunity.
METHODS : BALB/c mice were immunized with ethanol-killed MTB (EK-MTB) and MABs were produced and
screened by ELISA for binding to killed and live Mycobacterium smegmatis (SMEG) and MTB. MAB opsonophagocytic
killing activity (OPKA) was examined using SMEG with HL60 and U-937 cells and MTB with U-937 cells.
Clearance of MTB from blood was evaluated in Institute of Cancer Research (ICR) mice given opsonic anti-MTB
MABs or saline (control) 24 h prior to intravenous infusion with 108 CFUs gamma-irradiated MTB (HN878). MTB
levels in murine blood collected 0.25, 4 and 24 h post-challenge were assessed by qPCR. MAB binding to
peptidoglycan (PGN) was examined by ELISA using PGN cell wall mixture and ultra-pure PGN.
RESULTS : Two MABs (GG9 and JG7) bound to killed and live SMEG and MTB (susceptible and resistant), and
promoted OPKA with live MTB. MAB JG7 significantly enhanced OPKA of MTB. Both MABs significantly
enhanced clearance of killed MTB from murine blood at 4 and 24 h as measured by qPCR. These opsonic MABs
bound to PGN, a major cell wall constituent.
CONCLUSIONS : Anti-MTB MABs that promote bactericidal phagocytic activity of MTB and enhance clearance of killed
MTB from the blood, may offer an immunotherapeutic approach for treatment of MTB bacteremia or sepsis, and
augment treatment of multi-drug resistant (MDR) or extensively drug resistant (XDR) TB.This work was supported by Longhorn Vaccines and Diagnostics, LLC.
Live MTB work was additionally supported from post-graduate student
bursaries to Bong-Akee Shey from the University of Pretoria and from
grant 105830 to PBF by the National Research Foundation of South Africa.Post-graduate student
bursaries to Bong-Akee Shey from the University of Pretoria and from
grant 105830 to PBF by the National Research Foundation of South Africa.https://www.heliyon.comam2020Medical Microbiolog
A green-gray path to global water security and sustainable infrastructure
Sustainable development demands reliable water resources, yet traditional water management has broadly failed to avoid environmental degradation and contain infrastructure costs. We explore the global-scale feasibility of combining natural capital with engineering-based (green-gray) approaches to meet water security threats over the 21st century. Threats to water resource systems are projected to rise throughout this period, together with a significant expansion in engineering deployments and progressive loss of natural capital. In many parts of the world, strong path dependencies are projected to arise from the legacy of prior environmental degradation that constrains future water management to a heavy reliance on engineering-based approaches. Elsewhere, retaining existing stocks of natural capital creates opportunities to employ blended green-gray water infrastructure. By 2050, annual engineering expenditures are projected to triple to 3.0 trillion in avoided replacement costs by mid-century. Society pays a premium whenever these nature-based assets are lost, as the engineering costs necessary to achieve an equivalent level of threat management are, on average, twice as expensive. Countries projected to rapidly expand their engineering investments while losing natural capital will be most constrained in realizing green-gray water management. The situation is expected to be most restrictive across the developing world, where the economic, technical, and governance capacities to overcome such challenges remain limited. Our results demonstrate that policies that support blended green-gray approaches offer a pathway to future global water security but will require a strategic commitment to preserving natural capital. Absent such stewardship, the costs of water resource infrastructure and services will likely rise substantially and frustrate efforts to attain universal and sustainable water security
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