A homological interpretation of the transverse quiver Grassmannians

In recent articles, the investigation of atomic bases in cluster algebras associated to affine quivers led the second-named author to introduce a variety called transverse quiver Grassmannian and the first-named and third-named authors to consider the smooth loci of quiver Grassmannians. In this paper, we prove that, for any affine quiver Q, the transverse quiver Grassmannian of an indecomposable representation M is the set of points N in the quiver Grassmannian of M such that Ext^1(N,M/N)=0. As a corollary we prove that the transverse quiver Grassmannian coincides with the smooth locus of the irreducible components of minimal dimension in the quiver Grassmannian.Comment: final version, 7 pages, corollary 1.2 has been modifie

Measuring the proton spectrum in neutron decay - latest results with aSPECT

The retardation spectrometer aSPECT was built to measure the shape of the proton spectrum in free neutron decay with high precision. This allows us to determine the antineutrino electron angular correlation coefficient a. We aim for a precision more than one order of magnitude better than the present best value, which is Delta_a /a = 5%. In a recent beam time performed at the Institut Laue-Langevin during April / May 2008 we reached a statistical accuracy of about 2% per 24 hours measurement time. Several systematic effects were investigated experimentally. We expect the total relative uncertainty to be well below 5%.Comment: Accepted for publication in the Conference Proceedings of the International Workshop on Particle Physics with Slow Neutrons 2008 held at the ILL, France. To be published in Nuclear Instruments and Methods in Physics Research, Section

Rupture of multiple parallel molecular bonds under dynamic loading

Biological adhesion often involves several pairs of specific receptor-ligand molecules. Using rate equations, we study theoretically the rupture of such multiple parallel bonds under dynamic loading assisted by thermal activation. For a simple generic type of cooperativity, both the rupture time and force exhibit several different scaling regimes. The dependence of the rupture force on the number of bonds is predicted to be either linear, like a square root or logarithmic.Comment: 8 pages, 2 figure

Effects of disorder in location and size of fence barriers on molecular motion in cell membranes

The effect of disorder in the energetic heights and in the physical locations of fence barriers encountered by transmembrane molecules such as proteins and lipids in their motion in cell membranes is studied theoretically. The investigation takes as its starting point a recent analysis of a periodic system with constant distances between barriers and constant values of barrier heights, and employs effective medium theory to treat the disorder. The calculations make possible, in principle, the extraction of confinement parameters such as mean compartment sizes and mean intercompartmental transition rates from experimentally reported published observations. The analysis should be helpful both as an unusual application of effective medium theory and as an investigation of observed molecular movements in cell membranes.Comment: 9 pages, 5 figure

Stress-Dependent Impairment Of Passive-Avoidance Memory By Propranolol Or Naloxone

Previous work has shown that the effect of opioid-receptor blockade on memory modulation is critically dependent upon the intensity of stress. The current study determined the effect of adrenergic-receptor blockade on memory modulation under varied levels of stress and then compared the effect of adrenergic-receptor blockade under intense stress to that of a) opioid-receptor blockade and b) concurrent opioid- and adrenergic-receptor blockade. In the first experiment, the β-adrenergic-receptor blocker propranolol impaired retention in the passive-avoidance procedure when administered immediately after exposure to intense stress (passive-avoidance training followed by swim stress) but not mild stress (passive-avoidance training alone). In the second experiment, while separate administration of either propranolol or the opioid-receptor blocker naloxone immediately after exposure to intense stress impaired retention, the combined administration of propranolol and naloxone failed to do so. These findings demonstrate that the effect of β-adrenergic-receptor blockade or opioid-receptor blockade on memory modulation in the passive-avoidance procedure is dependent upon the intensity of stress, and suggest that concurrent inactivation of endogenous adrenergic- and opioid-based memory modulation systems under stressful conditions is protective of memory

An Epidemiology of Reported Needlestick Injuries among Health Care Workers in Sabah Health Government Facilities from 1999 – 2008

Introduction: Health care workers (HCWs) are at a high risk of occupational exposure to blood and body fluids of patients, resulting in possible transmission of blood- borne pathogens such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus. The information on epidemiology of needle stick injury among HCWs is useful in recommending safer work practices. Materials and Methods: All cases of NSI reported within the period 1999 to 2008 from public health care facilities to the Sabah State Health Department were identified and analyzed accordingly. NSI is defined as any injury caused by hollow- bore needles or suture needles regardless of whether they are contaminated by blood/ body fluids or not. Health care worker is defined as Ministry of Health staff, trainees and health facilities support service workers. The software used for data analysis was SPSS version 15.0. Results: A total of 378 cases of NSI were notified after considering NSI definition. Majority of HCWs involved in NSI were from the younger age group (20-29 years old, 61.9%), female gender (76.1%), Kadazan Dusun Murut ethnicity (33.5%), nurses (41.1%) and those who had worked for more than one year (66.6%). The place of occurrence was mostly in Kota Kinabalu district (25.3%), hospital setting (90.5%) and in- patient wards (60.8%). Of this in– patient ward, 64.5% was in medical and surgical wards. About 60% of NSI occurred during the morning shift (7am-2pm) and mostly among the nurses (54.0%). The duration of seeking treatment from injury was mostly within 24 hours (83.3%). The mechanism of accident happens while performing disposal activity (35.3%) and followed by any clinical procedure involving needle (31.1%). Other mechanism of accident was recapping (17.6%) and jolted/ accident (16.1%). Of all the reported NSI, 53.1% involved intravenous procedure. The body part involved in injury was mostly the right finger (57.1%). Almost all the needles were contaminated with blood or body fluid (90.0%). Post injury management, 73.5% were given first aid treatment and 99.4% were not awarded any medical leave. Existing control measures for NSI were standard operating procedure (SOP) (47.9%), training (36.9%) and PPE (10.5%). Conclusion: NSI commonly occurred among nurses, those in the younger age group and those working in medical/ surgical ward. Working during morning shift seems to predispose nurses to NSI. Since most NSI occurred during intravenous procedure and disposal activity, safer work practices should be emphasized to minimize these injuries. Further study in hospital and primary health care setting will determine the details of contributing factors of NSI

An Epidemiology of Reported Needlestick Injuries among Health Care Workers in Sabah Health Government Facilities from 1999 – 2008

Introduction: Health care workers (HCWs) are at a high risk of occupational exposure to blood and body fluids of patients, resulting in possible transmission of blood- borne pathogens such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus. The information on epidemiology of needle stick injury among HCWs is useful in recommending safer work practices. Materials and Methods: All cases of NSI reported within the period 1999 to 2008 from public health care facilities to the Sabah State Health Department were identified and analyzed accordingly. NSI is defined as any injury caused by hollow- bore needles or suture needles regardless of whether they are contaminated by blood/ body fluids or not. Health care worker is defined as Ministry of Health staff, trainees and health facilities support service workers. The software used for data analysis was SPSS version 15.0. Results: A total of 378 cases of NSI were notified after considering NSI definition. Majority of HCWs involved in NSI were from the younger age group (20-29 years old, 61.9%), female gender (76.1%), Kadazan Dusun Murut ethnicity (33.5%), nurses (41.1%) and those who had worked for more than one year (66.6%). The place of occurrence was mostly in Kota Kinabalu district (25.3%), hospital setting (90.5%) and in- patient wards (60.8%). Of this in– patient ward, 64.5% was in medical and surgical wards. About 60% of NSI occurred during the morning shift (7am-2pm) and mostly among the nurses (54.0%). The duration of seeking treatment from injury was mostly within 24 hours (83.3%). The mechanism of accident happens while performing disposal activity (35.3%) and followed by any clinical procedure involving needle (31.1%). Other mechanism of accident was recapping (17.6%) and jolted/ accident (16.1%). Of all the reported NSI, 53.1% involved intravenous procedure. The body part involved in injury was mostly the right finger (57.1%). Almost all the needles were contaminated with blood or body fluid (90.0%). Post injury management, 73.5% were given first aid treatment and 99.4% were not awarded any medical leave. Existing control measures for NSI were standard operating procedure (SOP) (47.9%), training (36.9%) and PPE (10.5%). Conclusion: NSI commonly occurred among nurses, those in the younger age group and those working in medical/ surgical ward. Working during morning shift seems to predispose nurses to NSI. Since most NSI occurred during intravenous procedure and disposal activity, safer work practices should be emphasized to minimize these injuries. Further study in hospital and primary health care setting will determine the details of contributing factors of NSI

Stress-Dependent Opioid And Adrenergic Modulation Of Newly Retrieved Fear Memory

Recent studies on the effect of stress on modulation of fear memory in our laboratory have uncovered endogenous opioid and adrenergic based modulation systems, working in concert, that limit the strengthening or weakening of newly acquired fear memory during consolidation under conditions of mild or intense stress, respectively. The present study sought to determine if similar stress-dependent modulation, mediated by endogenous opioid and adrenergic systems, occurs during reconsolidation of newly retrieved fear memory. Rats underwent contextual fear conditioning followed 24 h later by reactivation of fear memory; a retention test was administered the next day. Stress was manipulated by varying duration of recall of fear memory during reactivation. In the first experiment, vehicle or the opioid-receptor blocker naloxone was administered immediately after varied durations (30 or 120 s) of reactivation. The results indicate that (1) reactivation, in the absence of drug, has a marked effect on freezing behavior-as duration of reactivation increases from 30 to 120 s, freezing behavior and presumably fear-induced stress increases and (2) naloxone, administered immediately after 30 s (mild stress) or 120 s (intense stress) of reactivation, enhances or impairs retention, respectively, the next day. In the second experiment, naloxone and the g-adrenergic blocker propranolol were administered either separately or in combination immediately after 120 s (intense stress) reactivation. The results indicate that separate administration of propranolol and naloxone impairs retention, while the combined administration fails to do so. Taken together the results of the two experiments are consistent with a protective mechanism, mediated by endogenous opioid and adrenergic systems working in concert, that limits enhancement and impairment of newly retrieved fear memory during reactivation in a stress-dependent manner. (C) 2013 Elsevier Inc. All rights reserved

Stress-Dependent Enhancement And Impairment Of Retention By Naloxone: Evidence For An Endogenous Opioid-Based Modulatory System Protective Of Memory

The opiate-receptor antagonist naloxone was administered to rats after passive-avoidance training either alone or in combination with forced-swim stress. A retention test revealed that while naloxone enhanced retention when administered alone, it impaired retention when administered in combination with forced-swim stress. The findings provide evidence for a “protective” endogenous opioid-based system that, when not blocked pharmacologically, limits enhancement or impairment of retention under conditions of mild and intense stress, respectively