Peak Effect in Superconductors: Melting of Larkin Domains

Motivated by the recent observations of the peak effect in high-$T_c$ YBCO superconductors, we reexamine the origin of this unusual phenomenon. We show that the mechanism based on the $k$-dependence (nonlocality) of the vortex-lattice tilt modulus $C_{44}({\bf k})$ cannot account for the essential feature of the peak effect. We propose a scenario in which the peak effect is related to the melting of Larkin domains. In our model, the rise of critical current with increasing temperature is a result of a crossover from the Larkin pinning length to the length scale set by thermally excited free dislocations.Comment: 13 pages, 2 figures, REVTE

The role of Volatile Anesthetics in Cardioprotection: a systematic review.

This review evaluates the mechanism of volatile anesthetics as cardioprotective agents in both clinical and laboratory research and furthermore assesses possible cardiac side effects upon usage. Cardiac as well as non-cardiac surgery may evoke perioperative adverse events including: ischemia, diverse arrhythmias and reperfusion injury. As volatile anesthetics have cardiovascular effects that can lead to hypotension, clinicians may choose to administer alternative anesthetics to patients with coronary artery disease, particularly if the patient has severe preoperative ischemia or cardiovascular instability. Increasing preclinical evidence demonstrated that administration of inhaled anesthetics - before and during surgery - reduces the degree of ischemia and reperfusion injury to the heart. Recently, this preclinical data has been implemented clinically, and beneficial effects have been found in some studies of patients undergoing coronary artery bypass graft surgery. Administration of volatile anesthetic gases was protective for patients undergoing cardiac surgery through manipulation of the potassium ATP (KATP) channel, mitochondrial permeability transition pore (mPTP), reactive oxygen species (ROS) production, as well as through cytoprotective Akt and extracellular-signal kinases (ERK) pathways. However, as not all studies have demonstrated improved outcomes, the risks for undesirable hemodynamic effects must be weighed against the possible benefits of using volatile anesthetics as a means to provide cardiac protection in patients with coronary artery disease who are undergoing surgery

The nature and role of trap states in a dendrimer-based organic field-effect transistor explosive sensor

We report the fabrication and charge transport characterization of carbazole dendrimer-based organic field-effect transistors (OFETs) for the sensing of explosive vapors. After exposure to para-nitrotoluene (pNT) vapor, the OFET channel carrier mobility decreases due to trapping induced by the absorbed pNT. The influence of trap states on transport in devices before and after exposure to pNT vapor has been determined using temperature-dependent measurements of the field-effect mobility. These data clearly show that the absorption of pNT vapor into the dendrimer active layer results in the formation of additional trap states. Such states inhibit charge transport by decreasing the density of conducting states. (C) 2013 AIP Publishing LLC

Mucus Sugar Content Shapes the Bacterial Community Structure in Thermally Stressed Acropora muricata

It has been proposed that the chemical composition of a coral’s mucus can influence the associated bacterial community. However, information on this topic is rare, and non-existent for corals that are under thermal stress. This study therefore compared the carbohydrate composition of mucus in the coral Acropora muricata when subjected to increasing thermal stress from 26°C to 31°C, and determined whether this composition correlated with any changes in the bacterial community. Results showed that, at lower temperatures, the main components of mucus were N-acetyl glucosamine and C6 sugars, but these constituted a significantly lower proportion of the mucus in thermally-stressed corals. The change in the mucus composition coincided with a shift from a γ-Proteobacteria- to a Verrucomicrobiae- and α-Proteobacteria-dominated community in the coral mucus. Bacteria in the class Cyanobacteria also started to become prominent in the mucus when the coral was thermally stressed. The increase in the relative abundance of the Verrucomicrobiae at higher temperature was strongly associated with a change in the proportion of fucose, glucose and mannose in the mucus. Increase in the relative abundance of α-Proteobacteria were associated with GalNAc and glucose, while the drop in relative abundance of γ-Proteobacteria at high temperature coincided with changes in fucose and mannose. Cyanobacteria were highly associated with arabinose and xylose. Changes in mucus composition and the bacterial community in the mucus layer occurred at 29°C, which were prior to visual signs of coral bleaching at 31°C. A compositional change in the coral mucus, induced by thermal stress could therefore be a key factor leading to a shift in the associated bacterial community. This, in turn, has the potential to impact the physiological function of the coral holobiont

Genetic study of congenital bile-duct dilatation identifies de novo and inherited variants in functionally related genes

Background: Congenital dilatation of the bile-duct (CDD) is a rare, mostly sporadic, disorder that results in bile retention with severe associated complications. CDD affects mainly Asians. To our knowledge, no genetic study has ever been conducted. Methods: We aim to identify genetic risk factors by a “trio-based” exome-sequencing approach, whereby 31 CDD probands and their unaffected parents were exome-sequenced. Seven-hundred controls from the local population were used to detect gene-sets significantly enriched with rare variants in CDD patients. Results: Twenty-one predicted damaging de novo variants (DNVs; 4 protein truncating and 17 missense) were identified in several evolutionarily constrained genes (p < 0.01). Six genes carrying DNVs were associated with human developmental disorders involving epithelial, connective or bone morphologies (PXDN, RTEL1, ANKRD11, MAP2K1, CYLD, ACAN) and four linked with cholangio- and hepatocellular carcinomas (PIK3CA, TLN1 CYLD, MAP2K1). Importantly, CDD patients have an excess of DNVs in cancer-related genes (p < 0.025). Thirteen genes were recurrently mutated at different sites, forming compound heterozygotes or functionally related complexes within patients. Conclusions: Our data supports a strong genetic basis for CDD and show that CDD is not only genetically heterogeneous but also non-monogenic, requiring mutations in more than one genes for the disease to develop. The data is consistent with the rarity and sporadic presentation of CDD

Advances in delimiting the Hilbert-Schmidt separability probability of real two-qubit systems

We seek to derive the probability--expressed in terms of the Hilbert-Schmidt (Euclidean or flat) metric--that a generic (nine-dimensional) real two-qubit system is separable, by implementing the well-known Peres-Horodecki test on the partial transposes (PT's) of the associated 4 x 4 density matrices). But the full implementation of the test--requiring that the determinant of the PT be nonnegative for separability to hold--appears to be, at least presently, computationally intractable. So, we have previously implemented--using the auxiliary concept of a diagonal-entry-parameterized separability function (DESF)--the weaker implied test of nonnegativity of the six 2 x 2 principal minors of the PT. This yielded an exact upper bound on the separability probability of 1024/{135 pi^2} =0.76854$. Here, we piece together (reflection-symmetric) results obtained by requiring that each of the four 3 x 3 principal minors of the PT, in turn, be nonnegative, giving an improved/reduced upper bound of 22/35 = 0.628571. Then, we conclude that a still further improved upper bound of 1129/2100 = 0.537619 can be found by similarly piecing together the (reflection-symmetric) results of enforcing the simultaneous nonnegativity of certain pairs of the four 3 x 3 principal minors. In deriving our improved upper bounds, we rely repeatedly upon the use of certain integrals over cubes that arise. Finally, we apply an independence assumption to a pair of DESF's that comes close to reproducing our numerical estimate of the true separability function.Comment: 16 pages, 9 figures, a few inadvertent misstatements made near the end are correcte

Reentrant Peak Effect in an anisotropic superconductor 2H-NbSe_2 : Role of disorder

The reentrant nature of Peak Effect is established in a single crystal of 2H-NbSe_2 via electrical transport and dc magnetisation studies. The role of disorder on the reentrant branch of PE has been examined in three single crystals with varying levels of quenched random disorder. Increasing disorder presumably shrinks the (H,T) parameter space over which vortex array retains spatial order. Although, the upper branch of the PE curve is somewhat robust, the lower reentrant branch of the same curve is strongly affected by disorder.Comment: 5 Pages of text, 4 figure

Impact of Preoperative Anemia in Patients Undergoing Peripheral Vascular Intervention

Objectives: Transcarotid artery revascularization (TCAR) is an emerging novel approach to carotid intervention, adopted and well-suited for high-risk patients. Our objective was to assess the outcomes of TCAR and determine its impact on the volume of carotid endarterectomy (CEA) and non-TCAR carotid artery stenting (CAS) in a single-state experience. Methods: A large statewide quality consortium registry was queried. The indications and outcomes of TCAR compared with CEA and non-TCAR CAS from January 2018 to October 2019 were reviewed. Non-TCAR CAS included transfemoral, transbrachial stenting and transcarotid stenting without the flow reversal technique. We also assessed the impact of TCAR on the trend of CEA and non-TCAR CAS performed, analyzing data from 2012 to 2019. Outcome comparisons were performed using the χ 2 and Mann-Whitney U tests, depending on the distribution of the outcomes. Results: A total of 438 TCARs were performed by 39 physicians in 16 hospitals; 60% of the patients were asymptomatic and 40% symptomatic. The TCAR indication was physiologic high risk for 369 patients (84%) and restenosis for 69 patients (16%), with most occurring after prior CEA (94%). Of the non-TCAR CAS cases, 94% were performed via transfemoral access. The patients undergoing non-TCAR CAS had the highest 30-day mortality ( P \u3c .001) and the highest incidence of 30-day new neurologic deficits ( P = .008) compared with the patients undergoing CEA and TCAR. CEA had the lowest myocardial infarction rate ( P = .015; Table). The number of TCAR procedures performed and the number of physicians and hospitals performing them increased during the 2-year period. Since the introduction of TCAR, no significant frequency decrease has occurred in the number of non-TCAR CAS or CEA cases by hospitals or physicians (Fig). However, a significant negative trend was found in the number of CEAs performed by physicians since 2012 ( P \u3c .001; Fig). Conclusions: TCAR is a safe method of carotid revascularization and is becoming an increasingly used method. TCAR has not affected the CEA hospital or physician volume since its introduction. CEA volumes and physician usage are declining, which could have future credentialing implications. In the present single-state experience, TCAR compared favorably with CEA and non-TCAR CAS might be less appealing because of its higher neurologic event rate

Plasma Aβ40 and Aβ42 and Alzheimer's Disease: Relation to Age, Mortality, and Risk

BACKGROUND: Plasma amyloid [beta]-peptide (A[beta]) 40 and A[beta]42 levels are increased in persons with mutations causing early-onset familial Alzheimer's disease (AD). Plasma A[beta]42 levels were also used to link microsatellite genetic markers to a putative AD genetic locus on chromosome 10 and were observed in patients with incipient sporadic AD. METHODS: The authors measured plasma A[beta]40 and A[beta]42 levels using a sandwich ELISA after the initial examination of 530 individuals participating in an epidemiologic study of aging and dementia. Participants were examined at 18-month intervals, and plasma A[beta]40 and A[beta]42 levels were repeated in 307 subjects 3 years after baseline. RESULTS: Compared with individuals who never developed AD, patients with AD at baseline and those who developed AD during the follow-up had significantly higher A[beta]42, but not A[beta]40, plasma levels. The risk of AD in the highest quartile of plasma A[beta]42 was increased by more than twofold over that in the lowest quartile. The highest plasma A[beta]42 levels were observed in patients with AD who died during the follow-up. Plasma A[beta]42, but not A[beta]40, levels decreased over time in patients with newly acquired AD. CONCLUSIONS: Plasma A[beta]40 and A[beta]42 increase with age and are strongly correlated with each other. Plasma A[beta]40 and A[beta]42 levels are elevated in some patients before and during the early stages of AD but decline thereafter. High plasma A[beta]42 levels may also be associated with mortality in patients with AD

Treatment differences by health insurance among outpatients with coronary artery disease

OBJECTIVES: To compare treatment rates by insurance status for 5 quality-of-care indicators for coronary artery disease (CAD) care related to medication treatment. METHOD: Within the NCDR's PINNACLE Registry, we identified 60,814 outpatients with CAD from 30 U.S. practices. Hierarchical modified Poisson regression models with practice site as a random effect were used to study the association between health insurance (no insurance, public or private health insurance) and 5 CAD quality measures. RESULTS: Of 60,814 patients, 5716 (9.4%) patients were uninsured and 11,962 (19.7%) had public insurance, whereas 43,136 (70.9%) were privately insured. After accounting for exclusions, uninsured patients with CAD were 9%, 12%, and 6% less likely to receive treatment with beta-blocker, ACE-I/ARB, and lipid lowering therapy, respectively, than privately insured patients, whereas patients with public insurance were 9% less likely to be prescribed ACE-I/ARB therapy. Most differences by insurance status were attenuated after adjusting for the site providing care. For example, whereas uninsured patients with left ventricular dysfunction and CAD were less likely to receive ACE-I/ARB therapy (unadjusted RR=0.88; 95% CI 0.84-0.93), this difference was eliminated after adjustment for site (adjusted RR=0.95; 95% CI 0.88-1.03; P=0.18). CONCLUSIONS: Within this national outpatient cardiac registry, uninsured patients were less likely to receive evidence-based medications for CAD. These disparities were explained by the site providing care. Efforts to reduce treatment differences by insurance status among cardiac outpatients may additionally need to focus on improving rates of evidence-based treatment at sites with high proportions of uninsured patients