The Development of Cesium Calcium Bromo-Iodide scintillator for X-ray and Gamma ray detection

CsCaI3:Eu [cesium calcium iodide doped with europium] is a promising scintillator material that can be grown from the melt, but undergoes a tetragonal to orthorhombic phase transition upon cooling at 255 °C [degrees Celsius], causing twinning and cloudiness. The purpose of this work is to suppress this solid to solid phase transition in the CsCaI3:Eu scintillator, which has a light yield of ~40000 ph/Mev and energy resolution at 662keV of ~4%, by halide replacement to form the compound CsCaBrxI3-x:Eu [cesium calcium bromo-iodide doped with europium]. Crystals 8 cm3 [cubic centimeters] in volume were grown using the vertical Bridgman method with varying bromine replacement from x=0.2 to x=1, resulting in improved transparency for crystals with bromine content x \u3e 0.6. Powder X-ray diffraction data coupled with differential scanning calorimetry and radioluminescence measurements were used to investigate structural modifications, melting point dependence and spectral emission dependence on the bromine/iodine ratio. Partial replacement of iodine by bromine improves optical quality and scintillation properties by stabilizing the structure, rendering it useful for isotope identification for national security applications. The composition CsCaBr0.8I2.2:Eu [cesium calcium bromo (0.8) iodide (2.2) doped with europium] was determined to be the best combination of improved structure and performance, and larger 22 and 38 mm Ø [diameter[ crystals were grown for further evaluation. Large size slabs showed good crystal quality and improved performance over CsCaI3Eu with 8.4% and 9.5% energy resolution at 662 keV, respectively. The improved performance this composition over CsCaI3:Eu introduces the possibility of its use for gamma spectroscopy in national security applications

Pigmentary Retinopathy and Chronic Subretinal Fluid Associated with Pseudoxanthoma Elasticum and Angioid Streaks

This article is a Photo Essay. Please download the PDF or view the article HTML.&nbsp

The Use of Tutoplast as an Adjunct in Scleral Buckle Procedure in Patients with Extremely Thin Sclera

Extremely thin sclera often necessitates abortion of scleral buckle procedures. In patients in whom a scleral buckle is desired, previous techniques have included the use of cyanoacrylate glue and continuing with surgery or placing donor tissue over the areas of thin sclera, but this can delay surgery. This was a retrospective review of three patients with thin sclera encountered during scleral buckling procedures. All patients had Tutoplast Pericardial Graft placed over the areas of thin sclera which allowed the scleral buckle to be sutured onto the Tutoplast rather than the thin sclera. Tutoplast Pericardial Graft is a useful adjunct in scleral buckle procedures with extremely thin sclera, and a scleral buckle can be safely placed over it and lead to successful retinal reattachment

The regulation of yeast homotypic vacuole fusion by phosphatidic acid and diacylglycerol

Eukaryotic membrane fusion is a highly conserved process that is necessary to maintain cellular homeostasis. Ultimately, two membrane compartments are brought to each other, direct contact is established, and the bilayers and lumenal contents mix. In Saccharomyces cerevisiae, homotypic vacuole fusion occurs through a series of well-defined phases. SNAREs are activated by their co-chaperones Sec18 (mammalian NSF) and Sec17 (mammalian α-SNAP) in an ATP dependent priming stage. Tethering first brings two fusing compartments into contact with each other via interactions between the Rab GTPase Ypt7 and its effector HOPS complex. Once tethered, compartments are pulled into tight contact with each other through the formation of trans-SNARE complexes during a docking stage. The final fusion stage proceeds through a hemifusion intermediate to pore formation and lumenal content mixing. The roles of proteins that carry out membrane fusion stages are well established, however the roles regulatory lipids at the membrane play are still unclear. Many specific regulatory lipids localize to the site of fusing vacuoles termed the “vertex ring” implying an important role for them throughout the fusion process. It has been shown that the minimal membrane lipid content necessary for fusion to occur includes ergosterol, phosphatidic acid (PA), diacylglycerol (DAG), and phosphoinositides. However, the interactions and effects each of these lipids has throughout the stages of membrane fusion has not been elucidated. This project aimed to identify specific regulatory roles for the lipids PA and DAG. Previous work identified the interconversion of the two lipids by the DAG kinase Dgk1 and PA phosphatase Pah1 may be important for vacuole fusion to effectively occur. Pah1 conversion of PA to DAG was shown to be necessary for SNARE priming activity and localization of key protein factors. We found that Sec18, the SNARE chaperone that carries out priming, is a PA binding protein. Addition of a PA-specific binding domain blocked this binding and displaced Sec18 from vacuolar membranes. Furthermore, exogenous PA addition blocked Sec18 priming activity similarly to chemical inhibition of Pah1. Vacuoles lacking Pah1 showed decreased recruitment of Sec18 to inactive SNAREs. This recruitment defect was reversible upon the introduction of Pah1 by complementation or exogenous addition. Taken together, our data suggest a direct role for the regulation of SNARE priming at the vacuole by membrane PA. We further investigated the effects PA has on Sec18 protein conformation by looking at effects on the protein’s structure during binding. We found that PA induced a conformation change in Sec18 protomers, but active hexameric Sec18 does not readily bind PA. Sec18 binding to PA resulted in different protein interactions with 1,8 ANS and different limited proteolysis profiles suggesting changes in protein conformation. No significant changes in secondary structure were determined by circular dichroism and no shifts in intrinsic tryptophan fluorescence of Sec18 were observed in the presence of PA. Molecular dynamic simulations predicted that significant protomer conformation changes occur between the monomeric and hexameric forms of Sec18. Furthermore, simulations predicted that PA binds to Sec18 at the protein’s hexamer interface. Together, our data suggest that PA may regulate Sec18 function by stabilizing its inactive monomeric form preventing formation of an active hexamer. At the endoplasmic reticulum, Dgk1 and Pah1 have been shown to direct oppose each other in the interconversion of DAG and PA. We deleted DGK1 and observed no reversal of vacuolar morphology from pah1∆ cells indicating the two enzymes do not directly offset each other at the vacuole. However, vacuoles from dgk1∆ cells did show enhanced fusion. This elevated fusion was attributed to an increase in the fusogenic lipid DAG at the vacuole. These vacuoles also had an increased resistance to inhibitors of the Rab GTPase Ypt7. Taken together, our results suggest a role for Dgk1 in regulating vacuole fusion by reducing membrane DAG levels and altering Ypt7 activity

Recertification and Reentry to Practice for Nurse Anesthetists: Determining Core Competencies and Evaluating Performance via High-Fidelity Simulation Technology

Introduction The National Board of Certification and Recertification for Nurse Anesthetistsaddressed a barrier to return to practice of uncertified practitioners by replacing required direct patient care experiences with high-fidelity simulation. Objectives The aims of this study were to: (a) validate a set of clinical activities for their relevance to reentry and determine if they could be replicated using simulation, (b) evaluate the content validity of an existing simulation scenario containing the proposed clinical activities and determine its substitutability for a clinical practicum, and (c) evaluate the validity of two methods to assess simulation performance. Methods A modified Delphi method incorporating an autonomous, anonymous, three-round online survey process using three unique expert certified registered nurse anesthetists groups was used to address each study aim. Results Twenty-seven clinical activities gained consensus as necessary to be assessed in the simulation. All 14 survey questions used to determine simulation content validity exceeded the minimum content validity index (CVI) value of 0.78, with a mean CVI of 0.99. The global rating scale CVI and the competency checklist CVI were 0.83 and 1.0, respectively. Conclusion The findings add to the existing literature supporting the utility of simulation for high-stakes provider assessment and certification

Deleting the yeast phospholipase d spo14 augments homotypic vacuole fusion

Membrane fusion is a necessary process that allows eukaryotic cells to carry and deliver cargo between organelles. The mechanisms and machinery involved in membrane fusion are conserved throughout eukaryotes, so the yeast vacuole provides an ideal model system to study. Yeast vacuole fusion proceeds through a series of stages that include priming, tethering, docking, and fusion. Phosphatidic acid (PA) is a glycerophospholipid present throughout eukaryotic organelle membranes. The conversion of PA to diacyglerol (DAG) has been shown to play an important role in the activity and recruitment of vacuole fusion protein factors during the priming and tethering stages. Increased PA levels at the vacuole have been shown to significantly inhibit each of these stages. In yeast, phospholipase D (Spo14) catalyzes the hydrolysis of phosphatidylcholine into choline and PA making it a protein of interest in our system. Spo14p activity has been shown to play a vital role in numerous cellular pathways, including signal transduction, membrane trafficking, and regulation of mitosis. Here we aim to identify a role for Spo14 activity in the regulation of yeast vacuolar membrane fusion. To date, we have demonstrated that deleting SPO14 causes a marked increase in vacuole fusion that may be attributed to a decrease in phosphatidic acid levels at the yeast vacuole.Ope

Results of surgical management of acute thromboembolic lower extremity ischemia

ObjectiveAcute lower extremity ischemia secondary to arterial thromboembolism is a common problem. Contemporary data regarding this problem are sparse. This report examines a 10-year single-center experience and describes the surgical management and outcomes observed.MethodsProcedural codes were used to identify consecutive patients treated surgically for acute lower extremity embolization from January 2002 to September 2012. Patients presenting >7 days after onset of symptoms, occlusion of grafts/stents, and cases secondary to trauma or iatrogenic injury were excluded. Data collected included demographics, medical comorbidities, presenting clinical characteristics, procedural specifics, and postoperative outcomes. Results were evaluated using descriptive statistics, product-limit survival analysis, and logistic regression multivariable modeling.ResultsThe study sample included 170 patients (47% female). Mean age was 69.1 ± 16.0 years. Of these, 82 patients (49%) had a previous history of atrial fibrillation, and four (2%) were therapeutically anticoagulated (international normalized ratio ≥2.0) at presentation. Presentation for 83% was >6 hours after symptom onset, and 9% presented with a concurrent acute stroke. Femoral artery exploration with embolectomy was the most common procedural management and was used for aortic, iliac, and infrainguinal occlusion. Ten patients (6%) required bypass for limb salvage during the initial operation. Local instillation of thrombolytic agents as an adjunct to embolectomy was used in 16%, fasciotomies were performed in 39%, and unexpected return to the operating room occurred in 24%. Ninety-day amputation above or below the knee was required during the index hospitalization in 26 patients (15%). In-hospital or 30-day mortality was 18%. Median (interquartile range) length of stay was 8 days (4, 16 days), and 36% of patients were discharged to a nursing facility. Recurrent extremity embolization occurred in 23 patients (14%) at a median interval of 1.6 months. The 5-year amputation freedom and survival estimates were 80% and 41%, respectively. Predictors of 90-day amputation included prior vascular surgery, gangrene, and fasciotomy. Predictors of 30-day mortality included age, history of coronary artery disease, prior vascular surgery, and concurrent stroke.ConclusionsDespite advances in contemporary medical care, lower extremity arterial embolization remains a condition that is associated with significant morbidity and mortality. Furthermore, the condition is resource-intensive to treat and is likely preventable (initially or in recurrence) in a substantial subset of patients

Süngülerin gölgesinde

Peyami Safa'nın Resimli Gazete'de tefrika edilen Süngülerin Gölgesinde adlı romanıTelif hakları nedeniyle romanın tam metni verilememiştir

Effect of Surveillance Method on Reported Characteristics of Lyme Disease, Connecticut, 1996–2007

The epidemiology of Lyme disease varies by surveillance method