Magnetic susceptibility of QCD at zero and at finite temperature from the lattice

The response of the QCD vacuum to a constant external (electro)magnetic field is studied through the tensor polarization of the chiral condensate and the magnetic susceptibility at zero and at finite temperature. We determine these quantities using lattice configurations generated with the tree-level Symanzik improved gauge action and N-f 1 + 1 + 1 flavors of stout smeared staggered quarks with physical masses. We carry out the renormalization of the observables under study and perform the continuum limit both at T > 0 and at T = 0, using different lattice spacings. Finite size effects are studied by using various spatial lattice volumes. The magnetic susceptibilities chi(f) reveal a spin-diamagnetic behavior; we obtain at zero temperature chi(u) = -(2.08 +/- 0.08) GeV-2, chi(d) = -(2.02 +/- 0.09) GeV-2 and chi(s) = -(3.4 +/- 1.4) GeV-2 for the up, down and strange quarks, respectively, in the (MS) over bar scheme at a renormalization scale of 2 GeV. We also find the polarization to change smoothly with the temperature in the confinement phase and then to drastically reduce around the transition region

The QCD phase diagram for external magnetic fields

The effect of an external (electro)magnetic field on the finite temperature transition of QCD is studied. We generate configurations at various values of the quantized magnetic flux with $N_f=2+1$ flavors of stout smeared staggered quarks, with physical masses. Thermodynamic observables including the chiral condensate and susceptibility, and the strange quark number susceptibility are measured as functions of the field strength. We perform the renormalization of the studied observables and extrapolate the results to the continuum limit using $N_t=6,8$ and 10 lattices. We also check for finite volume effects using various lattice volumes. We find from all of our observables that the transition temperature $T_c$ significantly decreases with increasing magnetic field. This is in conflict with various model calculations that predict an increasing $T_c(B)$. From a finite volume scaling analysis we find that the analytic crossover that is present at B=0 persists up to our largest magnetic fields $eB \approx 1 \textmd{GeV}^2$, and that the transition strength increases mildly up to this $eB\approx1 \textmd{GeV}^2$.Comment: 22 pages, 13 figure

Singular values of the Dirac operator in dense QCD-like theories

We study the singular values of the Dirac operator in dense QCD-like theories at zero temperature. The Dirac singular values are real and nonnegative at any nonzero quark density. The scale of their spectrum is set by the diquark condensate, in contrast to the complex Dirac eigenvalues whose scale is set by the chiral condensate at low density and by the BCS gap at high density. We identify three different low-energy effective theories with diquark sources applicable at low, intermediate, and high density, together with their overlapping domains of validity. We derive a number of exact formulas for the Dirac singular values, including Banks-Casher-type relations for the diquark condensate, Smilga-Stern-type relations for the slope of the singular value density, and Leutwyler-Smilga-type sum rules for the inverse singular values. We construct random matrix theories and determine the form of the microscopic spectral correlation functions of the singular values for all nonzero quark densities. We also derive a rigorous index theorem for non-Hermitian Dirac operators. Our results can in principle be tested in lattice simulations.Comment: 3 references added, version published in JHE

Dissection and hemostasis with hydroxilated polyvinyl acetal tampons in open thyroid surgery

BACKGROUND: The essential objectives for thyroidectomy are: avoidance of injury to the recurrent laryngeal nerves, conservation of the parathyroid glands, an accurate haemostasis and an excellent cosmesis. In the last 10 years major improvements and new technologies have been proposed and applied in thyroid surgery; among these mini-invasive thyroidectomy, regional anaesthesia and intraoperative neuromonitoring, and new devices for achieving dissection and haemostasis. Minor bleeding from small vessels could be a major complication in thyroid surgery. The purpose of ligating vessels is to maintain the surgical site free from an excess of blood and reduce blood loss in the patient. MATERIALS AND METHODS: Hydroxylated polyvinyl acetal tampons (HPA) are made by a synthetic, open cell foam structure able to absorb fluids up to 25 times the initial weight. We tested their efficacy for small bleeding control and tissue dissection during several thyroid procedures. RESULTS: HPA tampons have been found extremely useful to absorb blood coming from minor and diffuse loss, helping to control bleeding by a combined action of fluid absorption and local compression. The porous design of the tampon allows the use of the suction device right through the tampon itself. Thanks to the initial mildly hard consistency, we also used HPA tampons as dissecting instruments. CONCLUSION: In our experience the use of HPA tampons resulted extremely efficient for minor bleeding control, fluids removal and tissue dissection during thyroid surgery

Src Dependent Pancreatic Acinar Injury Can Be Initiated Independent of an Increase in Cytosolic Calcium

Several deleterious intra-acinar phenomena are simultaneously triggered on initiating acute pancreatitis. These culminate in acinar injury or inflammatory mediator generation in vitro and parenchymal damage in vivo. Supraphysiologic caerulein is one such initiator which simultaneously activates numerous signaling pathways including non-receptor tyrosine kinases such as of the Src family. It also causes a sustained increase in cytosolic calcium- a player thought to be crucial in regulating deleterious phenomena. We have shown Src to be involved in caerulein induced actin remodeling, and caerulein induced changes in the Golgi and post-Golgi trafficking to be involved in trypsinogen activation, which initiates acinar cell injury. However, it remains unclear whether an increase in cytosolic calcium is necessary to initiate acinar injury or if injury can be initiated at basal cytosolic calcium levels by an alternate pathway. To study the interplay between tyrosine kinase signaling and calcium, we treated mouse pancreatic acinar cells with the tyrosine phosphatase inhibitor pervanadate. We studied the effect of the clinically used Src inhibitor Dasatinib (BMS-354825) on pervanadate or caerulein induced changes in Src activation, trypsinogen activation, cell injury, upstream cytosolic calcium, actin and Golgi morphology. Pervanadate, like supraphysiologic caerulein, induced Src activation, redistribution of the F-actin from its normal location in the sub-apical area to the basolateral areas, and caused antegrade fragmentation of the Golgi. These changes, like those induced by supraphysiologic caerulein, were associated with trypsinogen activation and acinar injury, all of which were prevented by Dasatinib. Interestingly, however, pervanadate did not cause an increase in cytosolic calcium, and the caerulein induced increase in cytosolic calcium was not affected by Dasatinib. These findings suggest that intra-acinar deleterious phenomena may be initiated independent of an increase in cytosolic calcium. Other players resulting in acinar injury along with the Src family of tyrosine kinases remain to be explored. © 2013 Mishra et al

Dental management considerations for the patient with an acquired coagulopathy. Part 1: Coagulopathies from systemic disease

Current teaching suggests that many patients are at risk for prolonged bleeding during and following invasive dental procedures, due to an acquired coagulopathy from systemic disease and/or from medications. However, treatment standards for these patients often are the result of long-standing dogma with little or no scientific basis. The medical history is critical for the identification of patients potentially at risk for prolonged bleeding from dental treatment. Some time-honoured laboratory tests have little or no use in community dental practice. Loss of functioning hepatic, renal, or bone marrow tissue predisposes to acquired coagulopathies through different mechanisms, but the relationship to oral haemostasis is poorly understood. Given the lack of established, science-based standards, proper dental management requires an understanding of certain principles of pathophysiology for these medical conditions and a few standard laboratory tests. Making changes in anticoagulant drug regimens are often unwarranted and/or expensive, and can put patients at far greater risk for morbidity and mortality than the unlikely outcome of postoperative bleeding. It should be recognised that prolonged bleeding is a rare event following invasive dental procedures, and therefore the vast majority of patients with suspected acquired coagulopathies are best managed in the community practice setting

A Comparison of Administrative and Physiologic Predictive Models in Determining Risk Adjusted Mortality Rates in Critically Ill Patients

Hospitals are increasingly compared based on clinical outcomes adjusted for severity of illness. Multiple methods exist to adjust for differences between patients. The challenge for consumers of this information, both the public and healthcare providers, is interpreting differences in risk adjustment models particularly when models differ in their use of administrative and physiologic data. We set to examine how administrative and physiologic models compare to each when applied to critically ill patients.We prospectively abstracted variables for a physiologic and administrative model of mortality from two intensive care units in the United States. Predicted mortality was compared through the Pearsons Product coefficient and Bland-Altman analysis. A subgroup of patients admitted directly from the emergency department was analyzed to remove potential confounding changes in condition prior to ICU admission.We included 556 patients from two academic medical centers in this analysis. The administrative model and physiologic models predicted mortalities for the combined cohort were 15.3% (95% CI 13.7%, 16.8%) and 24.6% (95% CI 22.7%, 26.5%) (t-test p-value<0.001). The r(2) for these models was 0.297. The Bland-Atlman plot suggests that at low predicted mortality there was good agreement; however, as mortality increased the models diverged. Similar results were found when analyzing a subgroup of patients admitted directly from the emergency department. When comparing the two hospitals, there was a statistical difference when using the administrative model but not the physiologic model. Unexplained mortality, defined as those patients who died who had a predicted mortality less than 10%, was a rare event by either model.In conclusion, while it has been shown that administrative models provide estimates of mortality that are similar to physiologic models in non-critically ill patients with pneumonia, our results suggest this finding can not be applied globally to patients admitted to intensive care units. As patients and providers increasingly use publicly reported information in making health care decisions and referrals, it is critical that the provided information be understood. Our results suggest that severity of illness may influence the mortality index in administrative models. We suggest that when interpreting "report cards" or metrics, health care providers determine how the risk adjustment was made and compares to other risk adjustment models

Response of bone turnover markers to raloxifene treatment in postmenopausal women with osteopenia.

Introduction: The change in bone turnover markers (BTM) in response to osteoporosis therapy can be assessed by a decrease beyond the least significant change (LSC) or below the mean of the reference interval (RI). We compared the performance of these two approaches in women treated with raloxifene. Methods: Fifty postmenopausal osteopenic women, (age 51-72y) were randomised to raloxifene or no treatment for 2 years. Blood samples were collected for the measurement of BTM. The LSC for each marker was calculated from the untreated women and the RI obtained from healthy premenopausal women (age 35-40y). Bone mineral density (BMD) was measured at the spine and hip. Results: There was a decrease in BTM in response to raloxifene treatment; percentage change at 12 weeks, CTX -39% (95% CI -48 to -28) and PINP -32% (95% CI -40 to -23) P<0.001. The proportion of women classified as responding to treatment using LSC at 12 weeks was: CTX 38%, PINP 52%, at 48 weeks CTX 60%, PINP 65%. For the RI approach; at 12 weeks CTX and PINP 38%, at 48 weeks CTX 40%, PINP 45%. There was a significant difference in the change in spine BMD in the raloxifene treated group compared to the no-treatment group at week 48; difference 0.031 g/cm2, (95% CI 0.016 to 0.046, P<0.001). Conclusions: The two approaches identified women that reached the target for treatment using BTM. Both LSC and RI criteria appear useful in identifying treatment response but the two approaches do not fully overlap and may be complementary

Towards a Social Trust-Aware Recommender for Teachers

Fazeli, S., Drachsler, H., Brouns, F., & Sloep, P. B. (2014). Towards a Social Trust-aware Recommender for Teachers. In N. Manouselis, H. Drachsler, K. Verbert & O. C. Santos (Eds.), Recommender Systems for Technology Enhanced Learning (pp. 177-194): Springer New York.Online communities and networked learning provide teachers with social learning opportunities, allowing them to interact and collaborate with others in order to develop their personal and professional skills. However, with the large number of learning resources produced everyday, teachers need to find out what are the most suitable ones for them. In this paper, we introduce recommender systems as a potential solution to this . The setting is the Open Discovery Space (ODS) project. Unfortunately, due to the sparsity of the educational datasets most educational recommender systems cannot make accurate recommendations. To overcome this problem, we propose to enhance a trust-based recommender algorithm with social data obtained from monitoring the activities of teachers within the ODS platform. In this article, we outline the re-quirements of the ODS recommender system based on experiences reported in related TEL recommender system studies. In addition, we provide empirical ev-idence from a survey study with stakeholders of the ODS project to support the requirements identified from a literature study. Finally, we present an agenda for further research intended to find out which recommender system should ul-timately be deployed in the ODS platform.NELLL, EU 7th framework Open Discovery Spac