Predicting turning points

This paper presents a new method for predicting turning points. The paper formally defines a turning point; develops a probit model for estimating the probability of a turning point; and then examines both the in-sample and out-of-sample forecasting performance of the model. The model performs better than some other methods for predicting turning points.Econometric models

Impairments in neurogenesis are not tightly linked to depressive behavior in a transgenic mouse model of Alzheimer\u27s disease.

Alzheimer\u27s disease (AD), the most common cause of dementia, is also associated with depression. Although the precise mechanisms that lead to depression in AD are unknown, the impairments in adult hippocampal neurogenesis observed in AD may play a role. Adult-born neurons play a critical role in regulating both cognition and mood, and reduced hippocampal neurogenesis is associated with depression in other neurological disorders. To assess the relationship between Alzheimer\u27s disease, neurogenesis, and depression, we studied human amyloid precursor protein (hAPP) transgenic mice, a well-characterized model of AD. We report that reductions in hippocampal neurogenesis are evident early in disease progression in hAPP mice, but a mild depressive phenotype manifests only in later stages of disease. We found that hAPP mice exhibited a reduction in BrdU-positive cells in the subgranular zone of the dentate gyrus in the hippocampus, as well as a reduction in doublecortin-expressing cells, relative to nontransgenic controls at 5-7 months of age. These alterations in neurogenesis appeared to worsen with age, as the magnitude of reduction in doublecortin-expressing cells was greater in hAPP mice at 13-15 months of age. Only 13-15 month old hAPP mice exhibited depressive behavior in the tail suspension test. However, mice at both age groups exhibited deficits in spatial memory, which was observed in the Morris water maze test for hippocampus-dependent memory. These findings indicate that neurogenesis impairments are accompanied by cognitive deficits, but are not tightly linked to depressive behavior in hAPP mice

Versatile transporter apparatus for experiments with optically trapped Bose-Einstein condensates

We describe a versatile and simple scheme for producing magnetically and optically-trapped Rb-87 Bose-Einstein condensates, based on a moving-coil transporter apparatus. The apparatus features a TOP trap that incorporates the movable quadrupole coils used for magneto-optical trapping and long-distance magnetic transport of atomic clouds. As a stand-alone device, this trap allows for the stable production of condensates containing up to one million atoms. In combination with an optical dipole trap, the TOP trap acts as a funnel for efficient loading, after which the quadrupole coils can be retracted, thereby maximizing optical access. The robustness of this scheme is illustrated by realizing the superfluid-to-Mott insulator transition in a three-dimensional optical lattice

Quantum transport in quantum networks and photosynthetic complexes at the steady state

Recently, several works have analysed the efficiency of photosynthetic complexes in a transient scenario and how that efficiency is affected by environmental noise. Here, following a quantum master equation approach, we study the energy and excitation transport in fully connected networks both in general and in the particular case of the Fenna-Matthew-Olson complex. The analysis is carried out for the steady state of the system where the excitation energy is constantly "flowing" through the system. Steady state transport scenarios are particularly relevant if the evolution of the quantum system is not conditioned on the arrival of individual excitations. By adding dephasing to the system, we analyse the possibility of noise-enhancement of the quantum transport.Comment: 10 pages, single column, 6 figures. Accepted for publication in Plos On

ΔFosB Regulates Gene Expression and Cognitive Dysfunction in a Mouse Model of Alzheimer\u27s Disease.

Alzheimer\u27s disease (AD) is characterized by cognitive decline and 5- to 10-fold increased seizure incidence. How seizures contribute to cognitive decline in AD or other disorders is unclear. We show that spontaneous seizures increase expression of ΔFosB, a highly stable Fos-family transcription factor, in the hippocampus of an AD mouse model. ΔFosB suppressed expression of the immediate early gene c-Fos, which is critical for plasticity and cognition, by binding its promoter and triggering histone deacetylation. Acute histone deacetylase (HDAC) inhibition or inhibition of ΔFosB activity restored c-Fos induction and improved cognition in AD mice. Administration of seizure-inducing agents to nontransgenic mice also resulted in ΔFosB-mediated suppression of c-Fos, suggesting that this mechanism is not confined to AD mice. These results explain observations that c-Fos expression increases after acute neuronal activity but decreases with chronic activity. Moreover, these results indicate a general mechanism by which seizures contribute to persistent cognitive deficits, even during seizure-free periods

Mechanism of efficient anti-Markovnikov olefin hydroarylation catalyzed by homogeneous Ir(III) complexes

The mechanism of the hydroarylation reaction between unactivated olefins (ethylene, propylene, and styrene) and benzene catalyzed by [(R)Ir(μ-acac-O,O,C^3)-(acac-O,O)_2]_2 and [R-Ir(acac-O,O)_2(L)] (R = acetylacetonato, CH_3, CH_2CH_3, Ph, or CH_2CH_2Ph, and L = H_2O or pyridine) Ir(III) complexes was studied by experimental methods. The system is selective for generating the anti-Markovnikov product of linear alkylarenes (61 : 39 for benzene + propylene and 98 : 2 for benzene + styrene). The reaction mechanism was found to follow a rate law with first-order dependence on benzene and catalyst, but a non-linear dependence on olefin. ^(13)C-labelling studies with CH_3^(13)CH_2-Ir-Py showed that reversible β-hydride elimination is facile, but unproductive, giving exclusively saturated alkylarene products. The migration of the ^(13)C-label from the α to β-positions was found to be slower than the C–H activation of benzene (and thus formation of ethane and Ph-d_5-Ir-Py). Kinetic analysis under steady state conditions gave a ratio of the rate constants for CH activation and β-hydride elimination (k_(CH): k_β) of 0.5. The comparable magnitude of these rates suggests a common rate determining transition state/intermediate, which has been shown previously with B3LYP density functional theory (DFT) calculations. Overall, the mechanism of hydroarylation proceeds through a series of pre-equilibrium dissociative steps involving rupture of the dinuclear species or the loss of L from Ph-Ir-L to the solvento, 16-electron species, Ph-Ir(acac-O,O)_2-Sol (where Sol refers to coordinated solvent). This species then undergoes trans to cis isomerization of the acetylacetonato ligand to yield the pseudo octahedral species cis-Ph-Ir-Sol, which is followed by olefin insertion (the regioselective and rate determining step), and then activation of the C–H bond of an incoming benzene to generate the product and regenerate the catalyst

Towards experimental entanglement connection with atomic ensembles in the single excitation regime

We present a protocol for performing entanglement connection between pairs of atomic ensembles in the single excitation regime. Two pairs are prepared in an asynchronous fashion and then connected via a Bell measurement. The resulting state of the two remaining ensembles is mapped to photonic modes and a reduced density matrix is then reconstructed. Our observations confirm for the first time the creation of coherence between atomic systems that never interacted, a first step towards entanglement connection, a critical requirement for quantum networking and long distance quantum communications

Social deprivation and exposure to health promotion. A study of the distribution of health promotion resources to schools in England

This article has been made available through the Brunel Open Access Publishing Fund and is available from the specified link - Copyright @ 2010 Chivu and ReidpathBACKGROUND: Area deprivation is a known determinant of health. It is also known that area deprivation is associated with lower impact health promotion. It is less well known, however, whether deprived areas are less responsive to health promotion, or whether they are less exposed. Using data from a national, school-based campaign to promote vaccination against the human papilloma virus (HPV), the relationship between area deprivation and exposure was examined. METHODS: Taking advantage of a health promotion campaign to provide information to schools about HPV vaccination, a cross sectional study was conducted to examine the relationship between area level, social deprivation, and take-up of (i.e., exposure to) available health promotion material. The sample was 4,750 schools across England, including government maintained and independent schools. The relationship between area deprivation and exposure was examined using bi- and multivariate logistic regression. RESULTS: It was found that schools in the least deprived quintile had 1.32 times the odds of requesting health promotion materials than schools in the most deprived areas (p = .01). This effect was independent of the school size, the type of school, and the geographic region. Conclusion The relationship between area deprivation and the impact of health promotion may be due, at least in part, to differential levels of exposure. The study was limited in scope, pointing to the need for more research, but also points to potentially important policy implications

Correlation Between Trough Plasma Dabigatran Concentrations and Estimates of Glomerular Filtration Rate Based on Creatinine and Cystatin C

AIMS: Dabigatran is largely cleared by renal excretion. Renal function is thus a major determinant of trough dabigatran concentrations, which correlate with the risk of thromboembolic and haemorrhagic outcomes. Current dabigatran dosing guidelines use the Cockcroft–Gault (CG) equation to gauge renal function, instead of contemporary equations including the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations employing creatinine (CKD-EPI_Cr), cystatin C (CKD-EPI_Cys) and both renal biomarkers (CKD-EPI_CrCys). METHODS: A linear regression model including the dabigatran etexilate maintenance dose rate, relevant interacting drugs and genetic polymorphisms (including CES1), was used to analyse the relationship between the values from each renal function equation and trough steady-state plasma dabigatran concentrations. RESULTS: The median dose-corrected trough steady-state plasma dabigatran concentration in 52 patients (38–94 years) taking dabigatran etexilate was 60 µg/L (range 9–279). The dose-corrected trough concentration in a patient on phenytoin and phenobarbitone was >3 standard deviations below the cohort mean. The CG, CKD-EPI_Cr, CKD-EPI_Cys and CKD-EPI_CrCys equations explained (R(2), 95 % CI) 32 % (9–55), 37 % (12–60), 41 % (16–64) and 47 % (20–69) of the variability in dabigatran concentrations between patients, respectively. One-way analysis of variance (ANOVA) comparing the R(2) values for each equation was not statistically significant (p = 0.74). DISCUSSION: Estimates of renal function using the four equations accounted for 32–47 % of the variability in dabigatran concentrations between patients. We are the first to provide evidence that co-administration of phenytoin/phenobarbitone with dabigatran etexilate is associated with significantly reduced dabigatran exposure. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s40268-014-0045-9) contains supplementary material, which is available to authorized users

Student and Faculty Perceptions of Attendance Policies at a Polytechnic University

Student and Faculty Perceptions of Attendance Policies at a Polytechnic University The goal of an attendance policy is to improve the academic success of students. However,current literature does not provide clear conclusions whether enforcing an attendance policy actually improves student performance. This study explores student and faculty perceptions regarding the utility of attendance policies in undergraduate courses at a polytechnic university.Anonymous surveys were completed by 89 faculty members and 455 responses from five schools (Engineering, Engineering Technology and Management, Computer and Software Engineering, Architecture, and Arts and Sciences) on a single campus. Comparisons between theperceptions of students and faculty members are presented, as are comparisons between theperceptions of lower-level and upper-level students. Variations in perceptions based on major arealso highlighted. Finally, trends in perceptions regarding attendance policies in lower-level versus upper-level undergraduate courses are revealed.Students, regardless of major, class standing, or course level, reported attending more classes in courses that had attendance policies. The most significant impact of an attendance policy on class attendance was observed at the freshman level. While 84% of freshmen reported attending at least 90% of the classes in a course with an attendance policy, only 67% reported attending at that rate in a course without one. Qualitative data containing student and faculty attitudes towards attendance policies are also analyzed and discussed.Even though class attendance appeared to have improved as a result of attendance policies,students’ perceptions about these policies varied significantly. Overall, the majority of students(51%) believed that, for a course with an attendance policy, the policy positively affected final grades. For a course without an attendance policy, the majority (57%) felt that the lack of a policy had no impact of final grades. Faculty members’ perceptions about attendance policy likewise varied. Overall, 61% of the faculty members surveyed reported having an attendance policy in one or more of their courses. The majority of faculty members believed that an attendance policy led to improvements in students’ grades in lower-level courses, but not inupper-level courses. Collectively, this study can help instructors make better informed decisions about the use of attendance policies in their courses