Small Break Research Articles

Idiopathic preretinal glia in aging and age-related macular degeneration

During analysis of glia in wholemount aged human retinas, frequent projections onto the vitreal surface of the inner limiting membrane (ILM) were noted. The present study characterized these preretinal glial structures. The amount of glial cells on the vitreal side of the ILM was compared between eyes with age-related macular degeneration (AMD) and age-matched control eyes. Retinal wholemounts were stained for markers of retinal astrocytes and activated Müller cells (glial fibrillary acidic protein, GFAP), Müller cells (vimentin, glutamine synthetase) and microglia/hyalocytes (IBA-1). Retinal vessels were labeled with UEA lectin. Images were collected using a Zeiss LSM 710 confocal microscope. Retinas were then cryopreserved. Laminin labeling of cryosections determined the location of glial structures in relation to the ILM. All retinas investigated herein had varied amounts of preretinal glia. These glial structures were classified into three groups based on size: sprouts, blooms, and membranes. The simplest of the glial structures observed were focal sprouts of singular GFAP-positive cells or processes on the vitreal surface of the ILM. The intermediate structures observed, glial blooms, were created by multiple cells/processes exiting from a single point and extending along the vitreoretinal surface. The most extensive structures, glial membranes, consisted of compact networks of cells and processes. Preretinal glia were observed in all areas of the retina but they were most prominent over large vessels. While all glial blooms and membranes contained vimentin and GFAP-positive cells, these proteins did not always co-localize. Many areas had no preretinal GFAP but had numerous vimentin only glial sprouts. In double labeled glial sprouts, vimentin staining extended beyond that of GFAP. Hyalocytes and microglia were detected along with glial sprouts, blooms, and membranes. They did not, however, concentrate in the retina below these structures. Cross sectional analysis identified small breaks in the ILM above large retinal vessels through which glial cells exited the retina. Preretinal glial structures of varied sizes are a common occurrence in aged retinas and, in most cases, are subclinical. While all retinal glia are found in blooms, vimentin labeling suggests that Müller cells form the leading edge. All retinas investigated from eyes with active choroidal neovascularization (CNV) had extensive glial membranes on the vitreal surface of the ILM. Although these structures may be benign, they may exert traction on the retina as they spread along the vitreoretinal interface. In cases with CNV, glial cells in the vitreous could bind intravitreally injected anti-vascular endothelial growth factor. These preretinal glial structures indicate the remodeling of both astrocytes and Müller cells in aged retinas, in particular those with advanced AMD.

Lonely Together: The Psychological Divide Due to Social Networking Sites

We live in a world full of judgment and competition, inescapably comparing ourselves and being compared to those around us. The types of actions users take and the kinds of information they are adding to their Facebook walls and profiles are a reflection of their identities. You are your Facebook, basically, and despite all its socialness, Facebook is a deeply personal medium. The time spent earlier during a car ride to a daydream, or building fantasies during lunchtime at work, or those small breaks one took to gaze outside the window are now all time to connect with technology, reply to a text, log on to websites and check email or notifications. I feel robbed on my aloneness, to be rather a buzz of constant communication, that hinders my every moment, and there is always someone to reply to. I finalized this topic because I wanted to explore the need of projection of an online identity of one‟s self and if it is the performance and the constant simulation that keeps us stimulated and addicted or is it the reflection of the real onto our screens, because some of us project and consume, idealized images through Facebook, and researchers have been trying to figure out how all this flawlessness affects us in the real world.

Higgs→μτas an indication forS4flavor symmetry

Lepton flavor violating Higgs decays can arise in flavor symmetry models where the Higgs sector is responsible for both the electroweak and the flavor symmetry breaking. Here we advocate an ${S}_{4}$ three-Higgs-doublet model where tightly constrained flavor changing neutral currents are suppressed by a remnant ${Z}_{3}$ symmetry. A small breaking of this ${Z}_{3}$ symmetry can explain the $2.4\ensuremath{\sigma}$ excess of Higgs decay final states with a $\ensuremath{\mu}\ensuremath{\tau}$ topology reported recently by CMS if the new neutral scalars are light. The model also predicts sizable rates for lepton flavor violating Higgs decays in the $e\ensuremath{\tau}$ and $e\ensuremath{\mu}$ channels because of the unifying ${S}_{4}$ flavor symmetry.

An experimental investigation of phase separation of gas–liquid two-phase flow through a small break

This paper proposes a specially designed splitting device to study the phase separation of gas–liquid two-phase flow through a small break. The inner pipe diameter of the main test section is 40mm. A small hole with 2.5mm diameter was drilled at the main pipe wall to simulate the break. Three break orientation angles were tested, including 0° (side), −45° (inclined) and −90° (bottom) from horizontal orientation. Experiments were conducted in an air–water two-phase flow loop with a horizontal test section. Stratified wavy, annular and slug flows were observed. Experimental results show that phase separation is affected by the break location, flow pattern and gas and liquid superficial velocities. The fraction of liquid taken off of slug flow is observed much larger than that of stratified wavy or annular flows due to its particular flow behavior. A simplified correlation of break pressure difference is proposed in terms of break outlet mass flow rate and gas quality.

Pilot study of dynamic Bayesian networks approach for fault diagnostics and accident progression prediction in HTR-PM

The first high-temperature-reactor pebble-bed demonstration module (HTR-PM) is under construction currently in China. At the same time, development of a system that is used to support nuclear emergency response is in progress. The supporting system is expected to complete two tasks. The first one is diagnostics of the fault in the reactor based on abnormal sensor measurements obtained. The second one is prognostic of the accident progression based on sensor measurements obtained and operator actions. Both tasks will provide valuable guidance for emergency staff to take appropriate protective actions. Traditional method for the two tasks relies heavily on expert judgment, and has been proven to be inappropriate in some cases, such as Three Mile Island accident. To better perform the two tasks, dynamic Bayesian networks (DBN) is introduced in this paper and a pilot study based on the approach is carried out. DBN is advantageous in representing complex dynamic systems and taking full consideration of evidences obtained to perform diagnostics and prognostics. Pearl's loopy belief propagation (LBP) algorithm is recommended for diagnostics and prognostics in DBN. The DBN model of HTR-PM is created based on detailed system analysis and accident progression analysis. A small break loss of coolant accident (SBLOCA) is selected to illustrate the application of the DBN model of HTR-PM in fault diagnostics (FD) and accident progression prognostics (APP). Several advantages of DBN approach compared with other techniques are discussed. The pilot study lays the foundation for developing the nuclear emergency response supporting system (NERSS) for HTR-PM.

An analytical investigation of cold leg small break accidents of the ATLAS facility

A previous parametric study of the direct vessel injection (DVI) line breaks was re-evaluated to see its applicability to that of the cold leg (CL) pipe breaks in advanced thermal-hydraulic test loop for accident simulation (ATLAS). Evaluation results of the tests and analyses for the major parameters, e.g., the pressurizer (PZR) pressure, downcomer water level, collapsed core water level, and clad temperature, were compared for four different CL pipe break scenarios. The overall trends of the major parameters showed reasonable behaviors between the tests and analyses. The clad temperature showed conservative behaviors in the analyses using the suggested options. The suggested counter-current flow limit (CCFL) options for the fuel alignment plate (FAP) and cross-over legs (COLs) can be applicable to any small-break loss-of-coolant accident (SBLOCA) scenario for the CL pipe and DVI line breaks in the ATLAS tests.

Comparative study on effect of air–water and steam–water mediums on liquid entrainment through ADS-4 in AP1000

For the previous experiments of entrainment at T-junction, the air–cold water two-phase flow is always selected as working medium, and the theoretical models of liquid entrainment are established mainly based on the experimental data of air–water entrainment through a small break. The saturated steam–water entrainment experiments are gravely insufficient, especially the steam–water experiments of entrainment through a large size branch are even fewer. Hence, a scale-down experiment of steam–water entrainment at T-junction has been conducted referring to liquid entrainment through ADS-4 (Fourth Stage Automatic Depressurization System) in AP1000 nuclear plant. The steam–water experimental results are comprehensively compared with the results of the previous similar air–water experiment: The visualization research shows that the same entrainment phenomena can be observed including intermittent flow entrainment, stratified flow entrainment and annular flow entrainment; The transition conditions between the two entrainment phenomena have a little difference but can be negligible; The comparison of experimental data of entrainment onset and stable entrainment indicates that the experimental data of steam–water and air–water have the same change tendency, and the air–water correlation can agree well with the steam–water data. Hence, we can make a conclusion that effect of different working mediums on liquid entrainment is negligible. In addition, based on the analysis of model formation, we suppose that effect of the system pressure on entrainment can be neglected under 0.22MPa.

Fermion masses and mixing in general warped extra dimensional models

We analyze fermion masses and mixing in a general warped extra dimensional model, where all the Standard Model (SM) fields, including the Higgs, are allowed to propagate in the bulk. In this context, a slightly broken flavor symmetry imposed universally on all fermion fields, without distinction, can generate the full flavor structure of the SM, including quarks, charged leptons and neutrinos. For quarks and charged leptons, the exponential sensitivity of their wave functions to small flavor breaking effects yield hierarchical masses and mixing as it is usual in warped models with fermions in the bulk. In the neutrino sector, the exponential wave-function factors can be flavor blind and thus insensitive to the small flavor symmetry breaking effects, directly linking their masses and mixing angles to the flavor symmetric structure of the five-dimensional neutrino Yukawa couplings. The Higgs must be localized in the bulk and the model is more successful in generalized warped scenarios where the metric background solution is different than five-dimensional anti--de Sitter (${\mathrm{AdS}}_{5}$). We study these features in two simple frameworks, flavor complimentarity and flavor democracy, which provide specific predictions and correlations between quarks and leptons, testable as more precise data in the neutrino sector becomes available.

Some phenomenological studies of a U(1)R — lepton number model with a right handed neutrino

We discuss the Higgs sector and neutrino mass and mixing in the context of a supersymmetric model with a U(1)R symmetry augmented by a single right handed neutrino superfield. The lepton number of the standard model fermions are identified with the negative of their R-charges. The presence of the neutrino Yukawa coupling (f) plays a very interesting role in Dirac neutrino mass generation as well as providing a tree level correction to the Higgs boson mass, when f ∼ O(1). In order to fit the complete neutrino mass and mixing, a small breaking of the U(1)R symmetry is considered in the context of anomaly mediated supersymmetry breaking. We also show that when f ∼ 10-4, the right handed neutrino can be identified with a 7 keVsterile neutrino dark matter as recent studies have speculated.

Modeling of AP1000 and simulation of 10-inch cold leg small break LOCA using the CESAR thermal-hydraulic module of ASTEC

The Westinghouse AP1000 main characteristic that distinguish it with respects to the modern PWRs is the adoption of several Passive Core Cooling Systems (PCCS) to recover the normal operation or to mitigate the consequences in case of accident. In this paper, modeling and nodalisation of the Reactor Coolant System (RCS), the secondary circuit and all the PCCS for the AP1000 reactor have been studied and a 10-in. small break LOCA scenario has been analyzed using CESAR, the thermal-hydraulic module of the ASTEC V2r2 integral code. The simulation results were compared with those coming from the Westinghouse-developed NOTRUMP code used as reference, showing a reasonable agreement. In case of a 10 inches small break LOCA, the results indicate that the PCCS ensure that the fuel and cladding temperature and the other thermal-hydraulic parameters respect the safety criteria and the safety systems perform their design role during the transient, leading the plant to cold shutdown conditions.

Computer analyses on loop seal clearing experiment at PWR PACTEL

Water seal formation in the loop seal in pressurized water reactors can occur during a small or intermediate break loss-of-coolant accident, causing temporary fuel overheating. Quantification of the accuracy of overheating prediction is of interest in the best-estimate safety analyses, even though the peak cladding temperatures due to the water seal formation in the loop seal seldom approach acceptance criteria as such. The aim of this study was to test and evaluate the accuracy with which the thermal–hydraulic system code nodalizations of the PWR PACTEL predict loop seal clearing in a small break loss-of-coolant-accident test performed with the PWR PACTEL facility. PWR PACTEL is a thermal–hydraulic test facility with two loops and vertical inverted U-tube steam generators. Post-test simulations were performed with the TRACE and APROS system codes. In the post-test simulations, the main events of the transient such as the decrease in the core water level, depressurization of the primary circuit, and the behavior of the water seal formation and clearing in the loop seal were predicted satisfactorily by both codes. However, discrepancies with the experiment results were observed in the analyses with both codes, for example the core temperature excursions were halted too early and the peak temperature predictions were too low. The core water level increase caused by loop seal clearing was overestimated with both codes, and the pressure and temperature were overestimated on the secondary side of the steam generators. Loop Seal 2 was evidently cleared out while Loop Seal 1 remained closed, just like in the experiment. It was noticed that, which of the loop seals clears in the simulations, was sensitive on the nodalization structure and initial conditions. The simulations indicate that the PWR PACTEL nodalizations are capable of simulating loop seal clearing quantitatively well. A quantitative error in the non-conservative direction was observed in peak cladding temperatures in both codes.

Tu1201 Effects of Transcutaneous Electrical Acupuncuture on Vagal Function and CNS Control for Nausea in Patients With Diabetic Gastroparesis

The introduction of high resolution esophageal motility (HREM) has redefined the understanding of esophageal motor disorders (EMD) as new patterns have been identified. The prevalence of these disorders using HREM has not been studied in specific populations. AIM: Describe the prevalence of EMD in a Mexican population. METHDOS: A prospective study was conducted in four community referral hospitals (750 beds) of the metropolitan area of the northern Mexican city of Monterrey (third largest city in the country, population > 4 million). All consecutive patients referred for esophageal motility testing (EMT) during March 1st 2013 to August 31, 2014 were included. Data collected included demographics and indications. EMT was performed with Given ManoScanTM HREM and the Chicago Classification was employed for diagnostic criteria. All studies were interpreted by a single experienced gastroenterologist with focused interest on esophageal diseases. RESULTS: During the study period, 342 patients had EMT. Six were excluded due to inability to tolerate the test. A normal EMT was found in 214 (64%). The most frequent motor disorder recognized was frequent failed peristalsis (n = 35, 29%), followed by weak peristalsis with small breaks (n = 26, 21%). Table 1 summarizes our manometric findings grouped based on the test indication. CONCLUSIONS: This is the first descriptive study of a large Mexican population undergoing EMT using HREM. In this population, the majority of these patients were studied for GERD. Most patients (64%) had a normal test. For those with abnormal results, a spectrum of abnormalities was observed with peristaltic defects representing the most common abnormality. Further studies are required to compare the scope of our findings with USA and other world-wide populations. Table 1. Manometric findings

Tu1422 Questioning the Significance of Large and Small Breaks on High Resolution Esophageal Manometry With Liquids and Solids in Patients With Dysphagia

Tu1422 Questioning the Significance of Large and Small Breaks on High Resolution Esophageal Manometry With Liquids and Solids in Patients With Dysphagia

Dispersion relations of Nambu-Goldstone modes at finite temperature and density

We discuss the dispersion relations of Nambu-Goldstone (NG) modes associated with spontaneous breaking of internal symmetries at finite temperature and/or density. We show that the dispersion relations of type-A (I) and type-B (II) NG modes are linear and quadratic in momentum, whose imaginary parts are quadratic and quartic, respectively. In both cases, the real parts of the dispersion relations are larger than the imaginary parts when the momentum is small, so that the NG modes can propagate far away. We derive the gap formula for NG modes in the presence of a small explicit breaking term. We also discuss the gapped partners of type-B NG modes, when the expectation values of a charge density and a local operator that break the same symmetry coexist.

Lumped parameter method application in nuclear engineering – AP1000 DVI line break accident analysis by RELAP5

Based on the PWR best estimate program RELAP5/MOD3.3, the reactor coolant system and the passive core cooling system of AP1000 Nuclear Power Plant were modeled and analyzed. Some key transient parameters were obtained, including RCS pressure, break discharge, etc. The result is in close agreement with the result generated by NOTRUMP code from Westinghouse USA. The calculation results show that safeguard system of APl000 can effectively reduce the pressure of the first loop, also can prevent core uncovered. The safety of AP1000 during a small break Loss of Coolant Accident caused by DVI line breaking is verified.

First-principles study of electronic structure of Ce3+ centres in alkaline-earth fluorides including spin-orbit and scalar relativistic effects

In this paper we present the results of ab initio calculations of Ce3+ impurity centres in CaF2 crystal. The cubic and tetragonal (interstitial fluorine compensated) configurations of centres were considered. The embedded cluster approach with polarizible crystalline lattice and CASSCF/CASPT2 methods were used to study the structural configurations and electronic properties of defects under consideration. Scalar relativistic corrections were taken into account at Douglas-Kroll-Hess level and spin-orbit effects were calculated with the RASSI approach. Calculated optical absorption spectra for cubic and tetragonal centres demonstrate good agreement with the experiment. Small symmetry breaking displacements of neighbouring ions were observed for cubic Ce3+ centre ground state.

Water flow based geometric active deformable model for road network

A width and color based geometric active deformable model is proposed for road network extraction from remote sensing images with minimal human interception. Orientation and width of road are computed from a single manual seed point, from which the propagation starts both right and left hand directions of the starting point, which extracts the interconnected road network from the aerial or high spatial resolution satellite image automatically. Here the propagation (like water flow in canal with defined boundary) is restricted with color and width of the road. Road extraction is done for linear, curvilinear (U shape and S shape) roads first, irrespective of width and color. Then, this algorithm is improved to extract road with junctions in a shape of L, T and X along with center line. Roads with small break or disconnected roads are also extracts by a modified version of this same algorithm. This methodology is tested and evaluated with various remote sensing images. The experimental results show that the proposed method is efficient and extracting roads accurately with less computation time. However, in complex urban areas, the identification accuracy declines due to the various sizes of obstacles, over bridges, multilane etc.

Nanofluid application in post SB-LOCA transient in VVER-1000 NPP

This paper is the third in a series of four papers that the application of nanofluid as a coolant to improve heat transfer in a VVER-1000 nuclear reactor is investigated. In the first and second papers, neutronics and thermo-hydraulic behavior of nano-particles in normal operation mode of the reactor were reported. In this study, the effects of nanofluids in Small Break Loss of Coolant Accident (SB-LOCA) to complement the existing safety systems is investigated. During SB-LOCA transient, due to reduced mass flow rate and Reynolds number, flow boiling along with vapor formation around the fuel rods occur. The fuel assembly coolant channel of a VVER-1000 core is modeled using a CFD code and heat transfer coefficients, pressure drop and volume fraction distribution of phases are computed for water/Al2O3 nanofluid. We observe that with the escalation of heat transfer enhancement, due to reduction in void fraction, pressure drop along the channel is reduced. This new phenomenon of lower pressure drop along with heat transfer enhancement, would be a significant factor for the use of nanofluids during reactor SB-LOCA transients.

DİŞ HEKİMLİĞİNDE ERGONOMİ

Dentists are at risk in terms of pain, because of usually hold on particular position, use of highly precision instruments and make repetitive movements in narrow field of study. As well as pain in the musculoskeletal system, dentist could be encountered with restlessness. Avoidance of postural deficiencies, as well as subsequent pathological changes, such as muscle imbalances, muscle necrosis and spinal disk degeneration could be prevented assuring the application of ergonomics in dentistry. Exercises in accordance with advice of a physician should be done daily, the spaces between appointments and small breaks into the treatment session. Dentists could mantain their profession successfully and healthily long time carrying out regular excersize program, accurate posture and postioning strategies

Cold leg condensation model for analyzing loss-of-coolant accident in PWR

Direct contact condensation in the cold leg of pressurized water reactor is an important phenomenon during a postulated loss-of-coolant accident. The amount of condensation in the cold legs impacts the thermal hydraulic behavior of the reactor coolant system and eventually the integration of reactor nuclear core. A cold leg condensation model was developed for the WCOBRA/TRAC-TF2 safety analysis code. The model correlated the COSI test data and addressed the scaling issues with respect to geometry, pressure, and steam and water flow rates expected during a typical PWR LOCA. The correlation was found to be in good agreement with separate effects and integral effects experimental data and implemented in the WCOBRA/TRAC-TF2 safety analysis code. The cold leg condensation model was assessed against various small break and large break LOCA separate effects tests such as COSI experiments, ROSA experiments and UPTF experiments. Those experiments cover a wide range of cold leg dimensions, system pressures, mass flow rates, and fluid properties. All the predicted condensation results match reasonably well with the experimental data.Scalability discussions on the diameter, flow area, length, superficial velocity, Reynolds number of both cold leg and SI line, and Froude number of SI line in the Westinghouse COSI test facility were provided. The distortion of the SI jet Reynolds number is moderate. The scaling analysis together with the validation matrix covering a wide range of cold leg diameter, SI flow rate and SI Reynolds number support the scalability of the developed cold leg condensation model to the full scale PWR application.