Reward modulates spatial neglect

Copyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.BACKGROUND: Reward has been shown to affect attention in healthy individuals, but there have been no studies addressing whether reward influences attentional impairments in patients with focal brain damage. METHODS: Using two novel variants of a widely-used clinical cancellation task, we assessed whether reward modulated impaired attention in 10 individuals with left neglect secondary to right hemisphere stroke. RESULTS: Reward exposure significantly reduced neglect, as measured by total targets found, left-sided targets found and centre of cancellation, across the patient group. Lesion analysis showed that lack of response to reward was associated with damage to the ipsilateral striatum. CONCLUSIONS: This is the first experimental evidence that reward can modulate attentional impairments following brain damage. These results have significant implications for the development of behavioural and pharmacological therapies for patients with attentional disorders.PM is supported by a HEFCE Clinical Senior Lectureship Award and this research was funded by grants from the UK Academy of Medical Sciences/Wellcome Trust and the NIHR Biomedical Research Centre at Imperial College London. DS is supported by a grant from the UK Medical Research Council (89631). CR is supported by a Brunel Research Initiative Award (BRIEF) and a scientific bursary from the Bial foundation, Portugal

Does Size Matter in the Airline Industry?

Over the last decade, the U.S. airline industry has transformed itself through mergers, restructurings, bankruptcies, and dissolutions. Also during this time, the airline industry focused on a business model that was driven by an emphasis on asset utilization. This was driven by increasing the load factor to increase cost efficiencies through economies of scale so that the return on invested capital could be improved by reducing the operating costs. This study evaluates economies of scale and resultant cost efficiencies in the U.S. passenger airline industry for the period 2013 to 2018. The research finds that the airline industry is experiencing cost efficiencies with every increase in the size of the airline, but cost efficiencies are not evenly distributed. The paper also finds that the main source of cost efficiency appears to be aircraft maintenance expenses

Double Acetates of Pb(IV) & Sn(IV) Acetates

52

Effects of Dust Geometry in Lyman Alpha Galaxies at z = 4.4

Equivalent widths (EWs) observed in high-redshift Lyman alpha galaxies could be stronger than the EW intrinsic to the stellar population if dust is present residing in clumps in the inter-stellar medium (ISM). In this scenario, continuum photons could be extinguished while the Lyman alpha photons would be resonantly scattered by the clumps, eventually escaping the galaxy. We investigate this radiative transfer scenario with a new sample of six Lyman alpha galaxy candidates in the GOODS CDF-S, selected at z = 4.4 with ground-based narrow-band imaging obtained at CTIO. Grism spectra from the HST PEARS survey confirm that three objects are at z = 4.4, and that another object contains an active galactic nuclei (AGN). If we assume the other five (non-AGN) objects are at z = 4.4, they have rest-frame EWs from 47 -- 190 A. We present results of stellar population studies of these objects, constraining their rest-frame UV with HST and their rest-frame optical with Spitzer. Out of the four objects which we analyzed, three objects were best-fit to contain stellar populations with ages on the order of 1 Myr and stellar masses from 3 - 10 x 10^8 solar masses, with dust in the amount of A_1200 = 0.9 - 1.8 residing in a quasi-homogeneous distribution. However, one object (with a rest EW ~ 150 A) was best fit by an 800 Myr, 6.6 x 10^9 solar mass stellar population with a smaller amount of dust (A_1200 = 0.4) attenuating the continuum only. In this object, the EW was enhanced ~ 50% due to this dust. This suggests that large EW Lyman alpha galaxies are a diverse population. Preferential extinction of the continuum in a clumpy ISM deserves further investigation as a possible cause of the overabundance of large-EW objects that have been seen in narrow-band surveys in recent years.Comment: Submitted to the Astrophysical Journal. 35 pages, 7 figures and 4 table

Periodic Peritoneal Dialysis in End Stage Renal Disease: Is it Still Relevant? A Single Center Study from India

Background: High cost of maintenance hemodialysis (HD) and continuous ambulatory peritoneal dialysis (PD) in India has made renal replacement therapy out of reach of many patients with end stage renal disease (ESRD). Repeated puncture PD although inferior to HD biochemically, is easily and freely available across Rajasthan, India, and is simple to perform, and does not require sophisticated machines, thus making it an attractive option for dialysis for ESRD. Aim: To analyze the outcomes of periodic PD in patients with ESRD requiring dialysis support. Subjects and Methods: A prospective study analyzing the data of patients who underwent PD between August 2010 and January 2013 in Sawai Man Singh Hospital, Jaipur, India was conducted. Patients were divided into three groups based on the time period between first and second session of PD. Detailed demographic and clinical data during the study period were collected along with PD related complications. The main outcome studied was technique survival 1 year post initiation of PD. Results: 234 patients received an initial session of PD, of which 174 had a good response and were included in the study. 19 patients received the second PD within 7 days of first (Group 1), 45 patients within 8–14 days (Group 2) and 110 patients within 15–21 days (Group 3). The overall 1 year technique survival was 68.4% (91/133), with a rate of 50% (5/10), 56.8% (21/37), and 75.6% (65/86) for Group 1, Group 2, and Group 3, respectively. The time duration between first and second PD proved to be reliable indicator of the subsequent response, with a technique survival rate significantly lower in Group 1 patients compared to Groups 2 and 3 (P = 0.04). Median dialysis free days were 11, 16 and 21 days in Group 1, Group 2, and Group 3, respectively. Peritonitis rate observed was 2.1% (49/2261) during the study period. Conclusion: Periodic PD is a simple, safe and cheap procedure, which can be considered as used as a palliative measure in terminal uremia in underprivileged areas.Keywords: Peritoneal dialysis, End stage renal disease, Renal replacement therap

Assessment of quality of life in Indian patients with vitiligo, an observational study

Background: Vitiligo is the most common hypopigmentary disorder. In India, the incidence of vitiligo is 0.25-2.5%. It considerably influences the patient’s quality‑of‑life (QoL) and psychological well‑being.Methods: A prospective, observational study was conducted from April 2016 to September 2016 in dermatology outpatient department. Patients clinical characteristic were noted and Quality of life was assessed by using Vitiligo Quality of Life Questionnaires [VQLQ]. During item development, none of the questions were changed according to the results of cognitive and understand ability testing. The scale consisted of 25 questions. The answer to each question was scored as ‘never = 1’, ‘sometimes = 2’, ‘often = 3’ and ‘all the time = 4’, so the total score ranged between 25 and 100. Higher scores represented more severely impaired quality of life.Results: We enrolled 78 Vitiligo patients who were attending dermatology department for phototherapy. Out of them 53 were female. Mean age was 37.12±12.270. Most common age group was 31-40 years. Mean VLQL score 40.92±6.081. Patients were divided based on VQLQ score in Moderate (50-75) and Low score group (25-50). Vitiligo patients presented with symptoms of pain, irritation and itching (P<0.0001). Vitiligo patients when assessed for feeling domain were significantly embarrassed for their overall look and appearance. (P < 0.0001). When Personal relationship domain was analysed physical contact was a major concern (P <0.002). Patients suffering from Vitiligo were significantly worried about spread of vitiligo and occurrence of cancer (P<0.0001). Therapy for Vitiligo was time consuming time and was a work place challenge for the patients (P <0.0001). The reliability of VQLQ in our study was Cronbach’s α coefficient was 0.876.Conclusions: QoL impairment was relatively high in vitiligo patients. Medical intervention and counselling should focus to improve feelings, personal relationship, anxiety, school/work, leisure and symptom domains

Asteroid Belts in Debris Disk Twins: VEGA and FOMALHAUT

Vega and Fomalhaut, are similar in terms of mass, ages, and global debris disk properties; therefore, they are often referred as "debris disk twins". We present Spitzer 10-35 um spectroscopic data centered at both stars, and identify warm, unresolved excess emission in the close vicinity of Vega for the first time. The properties of the warm excess in Vega are further characterized with ancillary photometry in the mid infrared and resolved images in the far-infrared and submillimeter wavelengths. The Vega warm excess shares many similar properties with the one found around Fomalhaut. The emission shortward of ~30 um from both warm components is well described as a blackbody emission of ~170 K. Interestingly, two other systems, eps Eri and HR 8799, also show such an unresolved warm dust using the same approach. These warm components may be analogous to the solar system's zodiacal dust cloud, but of far greater. The dust temperature and tentative detections in the submillimeter suggest the warm excess arises from dust associated with a planetesimal ring located near the water-frost line and presumably created by processes occurring at similar locations in other debris systems as well. We also review the properties of the 2 um hot excess around Vega and Fomalhaut, showing that the dust responsible for the hot excess is not spatially associated with the dust we detected in the warm belt. We suggest it may arise from hot nano grains trapped in the magnetic field of the star. Finally, the separation between the warm and cold belt is rather large with an orbital ratio >~10 in all four systems. In light of the current upper limits on the masses of planetary objects and the large gap, we discuss the possible implications for their underlying planetary architecture, and suggest that multiple, low-mass planets likely reside between the two belts in Vega and Fomalhaut.Comment: 14 pages, accepted for publication in Ap

Signatures of Planets in Spatially Unresolved Disks

Main sequence stars are commonly surrounded by debris disks, composed of cold dust continuously replenished by a reservoir of undetected dust-producing planetesimals. In a planetary system with a belt of planetesimals (like the Solar System's Kuiper Belt) and one or more interior giant planets, the trapping of dust particles in the mean motion resonances with the planets can create structure in the dust disk, as the particles accumulate at certain semimajor axes. Sufficiently massive planets may also scatter and eject dust particles out of a planetary system, creating a dust depleted region inside the orbit of the planet. In anticipation of future observations of spatially unresolved debris disks with the Spitzer Space Telescope, we are interested in studying how the structure carved by planets affects the shape of the disk's spectral energy distribution (SED), and consequently if the SED can be used to infer the presence of planets. We numerically calculate the equilibrium spatial density distributions and SEDs of dust disks originated by a belt of planetesimals in the presence of interior giant planets in different planetary configurations, and for a representative sample of chemical compositions. The dynamical models are necessary to estimate the enhancement of particles near the mean motion resonances with the planets, and to determine how many particles drift inside the planet's orbit. Based on the SEDs and predicted $\it{Spitzer}$ colors we discuss what types of planetary systems can be distinguishable from one another and the main parameter degeneracies in the model SEDs.Comment: 40 pages (pre-print form), including 16 figures. Published in ApJ 200