Transport Properties of a spinon Fermi surface coupled to a U(1) gauge field

With the organic compound $\kappa$-(BEDT-TTF)$_2$-Cu$_2$(CN)$_3$ in mind, we consider a spin liquid system where a spinon Fermi surface is coupled to a U(1) gauge field. Using the non-equilibrium Green's function formalism, we derive the Quantum Boltzmann Equation (QBE) for this system. In this system, however, one cannot a priori assume the existence of Landau quasiparticles. We show that even without this assumption one can still derive a linearized equation for a generalized distribution function. We show that the divergence of the effective mass and of the finite temperature self-energy do not enter these transport coefficients and thus they are well-defined. Moreover, using a variational method, we calculate the temperature dependence of the spin resistivity and thermal conductivity of this system.Comment: 12 page

Dynamical Decoupling in Optical Fibers: Preserving Polarization Qubits from Birefringent Dephasing

One of the major challenges in quantum computation has been to preserve the coherence of a quantum system against dephasing effects of the environment. The information stored in photon polarization, for example, is quickly lost due to such dephasing, and it is crucial to preserve the input states when one tries to transmit quantum information encoded in the photons through a communication channel. We propose a dynamical decoupling sequence to protect photonic qubits from dephasing by integrating wave plates into optical fiber at prescribed locations. We simulate random birefringent noise along realistic lengths of optical fiber and study preservation of polarization qubits through such fibers enhanced with Carr-Purcell-Meiboom-Gill (CPMG) dynamical decoupling. This technique can maintain photonic qubit coherence at high fidelity, making a step towards achieving scalable and useful quantum communication with photonic qubits.Comment: 8 pages, 5 figure

Dose-finding designs for trials of molecularly targeted agents and immunotherapies

Recently, there has been a surge of early phase trials of molecularly targeted agents (MTAs) and immunotherapies. These new therapies have different toxicity profiles compared to cytotoxic therapies. MTAs can benefit from new trial designs that allow inclusion of low-grade toxicities, late-onset toxicities, addition of an efficacy endpoint, and flexibility in the specification of a target toxicity probability. To study the degree of adoption of these methods, we conducted a Web of Science search of articles published between 2008 and 2014 that describe phase 1 oncology trials. Trials were categorized based on the dose-finding design used and the type of drug studied. Out of 1,712 dose-finding trials that met our criteria, 1,591 (92.9%) utilized a rule-based design, and 92 (5.4%; range 2.3% in 2009 to 9.7% in 2014) utilized a model-based or novel design. Over half of the trials tested an MTA or immunotherapy. Among the MTA and immunotherapy trials, 5.8% used model-based methods, compared to 3.9% and 8.3% of the chemotherapy or radiotherapy trials, respectively. While the percentage of trials using novel dose-finding designs has tripled since 2007, only 7.1% of trials use novel designs

Postpartum circulating cell-free insulin DNA levels are higher in women with previous gestational diabetes mellitus who develop type 2 diabetes in later life

Background. Women with previous gestational diabetes mellitus (GDM) have evidence of postpartum β-cell dysfunction, which increases their risk of developing type 2 diabetes (T2DM) later in life. Elevated levels of circulating cell-free preproinsulin (INS) DNA correlate with dying β-cells in both mice and humans. The aim of this study was to determine if cell-free circulating INS DNA levels are higher in women with previous GDM who develop T2DM. Methods. We used droplet digital (dd) PCR to measure the levels of cell-free circulating methylated and unmethylated INS DNA in plasma from 97 women with normal glucose tolerance (NGT), 12 weeks following an index GDM pregnancy. Women were assessed for up to 10 years for the development of T2DM. Results. In the follow-up period, 22% of women developed T2DM. Compared with NGT women, total cell-free INS DNA levels were significantly higher in women who developed T2DM (P=0.02). There was no difference in cell-free circulating unmethylated and methylated INS DNA levels between NGT women and women who developed T2DM (P=0.09 and P=0.07, respectively). Conclusions. In women with a previous index GDM pregnancy, postpartum levels of cell-free circulating INS DNA are significantly higher in those women who later developed T2DM

Postpartum circulating cell-free insulin DNA levels are higher in women with previous gestational diabetes mellitus who develop type 2 diabetes in later life

Background. Women with previous gestational diabetes mellitus (GDM) have evidence of postpartum β-cell dysfunction, which increases their risk of developing type 2 diabetes (T2DM) later in life. Elevated levels of circulating cell-free preproinsulin (INS) DNA correlate with dying β-cells in both mice and humans. The aim of this study was to determine if cell-free circulating INS DNA levels are higher in women with previous GDM who develop T2DM. Methods. We used droplet digital (dd) PCR to measure the levels of cell-free circulating methylated and unmethylated INS DNA in plasma from 97 women with normal glucose tolerance (NGT), 12 weeks following an index GDM pregnancy. Women were assessed for up to 10 years for the development of T2DM. Results. In the follow-up period, 22% of women developed T2DM. Compared with NGT women, total cell-free INS DNA levels were significantly higher in women who developed T2DM (P=0.02). There was no difference in cell-free circulating unmethylated and methylated INS DNA levels between NGT women and women who developed T2DM (P=0.09 and P=0.07, respectively). Conclusions. In women with a previous index GDM pregnancy, postpartum levels of cell-free circulating INS DNA are significantly higher in those women who later developed T2DM

QMCPACK: Advances in the development, efficiency, and application of auxiliary field and real-space variational and diffusion Quantum Monte Carlo

We review recent advances in the capabilities of the open source ab initio Quantum Monte Carlo (QMC) package QMCPACK and the workflow tool Nexus used for greater efficiency and reproducibility. The auxiliary field QMC (AFQMC) implementation has been greatly expanded to include k-point symmetries, tensor-hypercontraction, and accelerated graphical processing unit (GPU) support. These scaling and memory reductions greatly increase the number of orbitals that can practically be included in AFQMC calculations, increasing accuracy. Advances in real space methods include techniques for accurate computation of band gaps and for systematically improving the nodal surface of ground state wavefunctions. Results of these calculations can be used to validate application of more approximate electronic structure methods including GW and density functional based techniques. To provide an improved foundation for these calculations we utilize a new set of correlation-consistent effective core potentials (pseudopotentials) that are more accurate than previous sets; these can also be applied in quantum-chemical and other many-body applications, not only QMC. These advances increase the efficiency, accuracy, and range of properties that can be studied in both molecules and materials with QMC and QMCPACK

Close companions around young stars

Multiplicity is a fundamental property that is set early during stellar lifetimes, and it is a stringent probe of the physics of star formation. The distribution of close companions around young stars is still poorly constrained by observations. We present an analysis of stellar multiplicity derived from APOGEE-2 spectra obtained in targeted observations of nearby star-forming regions. This is the largest homogeneously observed sample of high-resolution spectra of young stars. We developed an autonomous method to identify double lined spectroscopic binaries (SB2s). Out of 5007 sources spanning the mass range of $\sim$0.05--1.5 \msun, we find 399 binaries, including both RV variables and SB2s. The mass ratio distribution of SB2s is consistent with a uniform for $q0.95$. The period distribution is consistent with what has been observed in close binaries ($<10$ AU) in the evolved populations. Three systems are found to have $q\sim$0.1, with a companion located within the brown dwarf desert. There are not any strong trends in the multiplicity fraction (MF) as a function of cluster age from 1 to 100 Myr. There is a weak dependence on stellar density, with companions being most numerous at $\Sigma_*\sim30$ stars/pc$^{-2}$, and decreasing in more diffuse regions. Finally, disk-bearing sources are deficient in SB2s (but not RV variables) by a factor of $\sim$2; this deficit is recovered by the systems without disks. This may indicate a quick dispersal of disk material in short-period equal mass systems that is less effective in binaries with lower $q$.Comment: 25 pages, 20 figures. Accepted to A

Comparison of Clinician Suspicion Versus a Clinical Prediction Rule in Identifying Children at Risk for Intra‐abdominal Injuries After Blunt Torso Trauma

ObjectivesEmergency department (ED) identification and radiographic evaluation of children with intra‐abdominal injuries who need acute intervention can be challenging. To date, it is unclear if a clinical prediction rule is superior to unstructured clinician judgment in identifying these children. The objective of this study was to compare the test characteristics of clinician suspicion with a derived clinical prediction rule to identify children at risk of intra‐abdominal injuries undergoing acute intervention following blunt torso trauma.MethodsThis was a planned subanalysis of a prospective, multicenter observational study of children (50% prior to knowledge of abdominal computed tomography (CT) scanning (if performed). Intra‐abdominal injuries undergoing acute intervention were defined by a therapeutic laparotomy, angiographic embolization, blood transfusion for abdominal hemorrhage, or intravenous fluid administration for 2 or more days in those with pancreatic or gastrointestinal injuries. Patients were considered to be positive for clinician suspicion if suspicion was documented as ≥1%. Suspicion ≥ 1% was compared to the presence of any variable in the prediction rule for identifying children with intra‐abdominal injuries undergoing acute intervention.ResultsClinicians recorded their suspicion in 11,919 (99%) of 12,044 patients enrolled in the parent study. Intra‐abdominal injuries undergoing acute intervention were diagnosed in 203 (2%) patients. Abdominal CT scans were obtained in the ED in 2,302 of the 2,667 (86%, 95% confidence interval [CI] = 85% to 88%) enrolled patients with clinician suspicion ≥1% and in 3,016 of the 9,252 (33%, 95% CI = 32% to 34%) patients with clinician suspicion  50% previamente a conocer la tomografía computarizada (TC) abdominal (si fue realizada). La LIA con necesidad de intervención urgente se definió como laparotomía terapéutica, embolización angiográfica, transfusión de sangre por hemorragia intrabdominal o administración de fluidos intravenosos durante 2 o más días en aquéllos con lesiones pancreáticas o gastrointestinales. Los pacientes se consideraron positivos para la sospecha clínica si la sospecha se documentó como ≥1%. La sospecha > 1% se comparó con la presencia de cualquier variable en la regla de predicción para la identificación de niños con LIA con necesidad de una intervención urgente.ResultadosLos clínicos documentaron su sospecha en 11.919 (99%) de los 12.044 pacientes incluidos en el estudio original. La LIA con necesidad de intervención urgente se diagnosticó en 203 (2%) pacientes. Las TC abdominales se obtuvieron en el SU en 2.302 de los 2.667 pacientes (86%, IC95% = 85% a 88%) incluidos con sospecha clínica ≥1%; y en 3.016 de los 9.252 pacientes (33%, IC95% = 32% a 34%) con sospecha clínica < 1%. La sensibilidad de la regla de predicción para LIA con necesidad de intervención aguda fue mayor que la sospecha clínica ≥1% (197 de 203, 97,0%, IC95% = 93,7% a 98,9%, frente a 168 de 203, 82,8%, IC95% = 76,9% a 87,7%, respectivamente; diferencia de 14,2%, IC95% = 8,6% a 20,0%). La especificidad de la regla de predicción, sin embargo, fue menor que la sospecha clínica (4,979 de los 11.716, 42,5%, IC95% = 41,6% a 43,4%, frente a 9,217 de los 11.716, 78,7%, IC95% = 77,9% a 79,4%, respectivamente; diferencia de –36,2%, IC95% = –37,3% a –35,0%). Treinta y cinco de los pacientes con sospecha clínica < 1% (0,4%, IC95% = 0,3% a 0,5%) tuvieron LIA con necesidad de intervención urgente.ConclusionesLa regla de predicción clínica derivada tuvo una sensibilidad mayor de forma significativa, pero menor especificidad que la sospecha clínica para la identificación de niños con necesidad de una intervención urgente. La mayor especificidad de la sospecha clínica, sin embargo, no se tradujo en la práctica clínica, ya que los clínicos obtuvieron más frecuentemente TC abdominales en los pacientes que consideraron de muy bajo riesgo. Si se validase, esta regla de predicción puede ayudar en la toma de decisiones clínicas sobre el uso de TC abdominal en los niños con traumatismo torácico cerrado.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113736/1/acem12739.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/113736/2/acem12739_am.pd

Clinico-pathological profile of sinonasal masses: an experience in national ear care center Kaduna, Nigeria

<p>Abstract</p> <p>Background</p> <p>The presence of a mass in the nose and paranasal sinuses may seem to be a simple problem; however it raises many questions about the differential diagnosis. The aim of this study is to evaluate the clinico-pathological profile of sinonasal masses in our environment</p> <p>This is a retrospective analytical review of all the patients with sinonasal masses that presented to the national ear care center, Kaduna over a six year (2003-2008) period. Their biodata, clinical profile and histological diagnoses were analyzed.</p> <p>Findings</p> <p>A total of 76 patients were analyzed, age range 5 to 64 yrs with a mean age of 33.3 yr median and modal age of 35.00 (SD = 13.1 ± 1.5). Majority of the patients were in the age groups 21-50 yrs. There were 34 male and 42 female with M: F ratio of 1:1.2. The main presenting symptoms are nasal blockage 97.4% and rhinorrhea 94.7%. It was bilateral in 34 (44.7%), left side in 24(31.6%) and right side in 18(23.7%) patients. The commonest clinical diagnoses were simple nasal polyp 47(61.8%) and antrochoanal polyp 10(13.2%). About 59 (77.6%) were benign, 2 (2.6%) were malignant and 15 (19.7%) were lost to follow up. The commonest histological diagnosis is simple inflammatory nasal polyp in 28 (36.8%) patients and the least was nasal capillary hemangioma 2 (2.6%). About 55(72.4%) patients had surgical treatment.</p> <p>Conclusions</p> <p>Nasal obstruction and rhinorrhea are the commonest symptoms of presentation, simple inflammatory nasal polyp is still the commonest histological pattern seen in our environment, and surgery is still the best modality of treatment for benign tumor thus the need for advocacy for early recognition and referral to the ENT surgeon.</p