408 research outputs found
Hi Spin Temperatures and Heating Requirements in Outer Regions of Disk Galaxies
ABSRACT:We show how to use 21-cm emission and absorption studies to estimate
the heat inputs to the neutral gas in low pressure environments, such as in
outer disks of spiral galaxies, in galactic halos or in intergalactic space.
For a range of model parameters we calculate the gas kinetic and spin
temperatures ( and ) and the relation between and the heat
input to the gas. We outline the conditions for a ``two phase medium'' to
exist. We find that although can be much smaller than , is
always K for column densities greater that
cm. This excludes the possibility that relevant HI masses at the
periphery of galaxies are invisible at 21-cm in emission. The outermost
interstellar gas in a disk galaxy is more directly affected by external
processes and in this paper we estimate the intensity of the extragalactic
background at energies close to 0.1 keV by comparing our theoretical results
with HI emission/absorption studies. We take into account the possibility that
some energy produced in the inner regions affects the energy balance in outer
regions. We find that in the absence of any other local heat source QSO
dominated background models are still compatible with the spin temperature
limits derived for the two best documented HI emission/absorption studies in
outer regions.Comment: 24 pages, 8 figures ARCETRI-PR-93-2
Influence of polydispersity on the critical parameters of an effective potential model for asymmetric hard sphere mixtures
We report a Monte Carlo simulation study of the properties of highly
asymmetric binary hard sphere mixtures. This system is treated within an
effective fluid approximation in which the large particles interact through a
depletion potential (R. Roth {\em et al}, Phys. Rev. E{\bf 62} 5360 (2000))
designed to capture the effects of a virtual sea of small particles. We
generalize this depletion potential to include the effects of explicit size
dispersity in the large particles and consider the case in which the particle
diameters are distributed according to a Schulz form having degree of
polydispersity 14%. The resulting alteration (with respect to the monodisperse
limit) of the metastable fluid-fluid critical point parameters is determined
for two values of the ratio of the diameters of the small and large particles:
and . We find that inclusion of
polydispersity moves the critical point to lower reservoir volume fractions of
the small particles and high volume fractions of the large ones. The estimated
critical point parameters are found to be in good agreement with those
predicted by a generalized corresponding states argument which provides a link
to the known critical adhesion parameter of the adhesive hard sphere model.
Finite-size scaling estimates of the cluster percolation line in the one phase
fluid region indicate that inclusion of polydispersity moves the critical point
deeper into the percolating regime. This suggests that phase separation is more
likely to be preempted by dynamical arrest in polydisperse systems.Comment: 11 pages, 10 figure
An Inquiry into the Competitiveness of Emerging Philippine Cities
This paper attempts to approximate the competitiveness of the country’s ten leading emerging urban centers: Angeles, Baguio, Cagayan de Oro, Davao City, General Santos, Iligan, Iloilo, San Fernando La Union, Tacloban and Zamboanga. The study uses both ranking and scoring methods to rate the cities in eight major drivers: cost competitiveness, human resources endowment, infrastructure, linkages with major urban centers and growth areas, quality of life, responsive of local government units and dynamism of local economy. It best serves as a policy and urban management tool for concerned local officials and leaders of various private sector groups in identifying the cities’ strength and areas of improvement. Insights on overall scores and rankings point to the importance of local leadership, emphasis on improving quality of lives in urban centers and the role of surrounding local and/or international growth formations in enhancing urban competitiveness. Any combination of these factors actually explains the high rankings garnered by General Santos City, Angeles City and Baguio.urban management, urbanization, competitiveness, urban development
Pedestrian–vehicle interaction at unsignalized crosswalks: a systematic review
A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), to generate a document that supports the development of future research, compiling the various studies focused on the analysis of the pedestrian-vehicle interaction at unsignalized crosswalks. Firstly, 381 studies were identified by applying the search protocol in the database sources; however, only nine studies were included in this review because most of the studies are not focused on this type of crosswalks or have not considered the micro-simulation perspective. For each study, an analysis of the used methodology for data collection was carried out, in addition to what type of model it was applied, including the variables that represent the PVI (Pedestrian-Vehicle Interaction). The outcomes obtained by this systematic review show that although the video camera observation technique is the most used, it is possible to complement them with other tools to add specific field information. Additionally, variables such as the adjacent yields, speed variables vehicles, pedestrian attitude, and the number of pedestrians waiting at the crossing were those most used in the cellular automata model or micro-simulation, which are the commonly developed models to simulate this interaction.This research was funded by “Fundação para a Ciência e a Tecnologia”, through the project
AnPeB–Pedestrian behavior analysis based on simulated environments and their incorporation into risk modeling
(PTDC/ECMTRA/3568/2014)
92 OESTROGEN DEFICIENCY, BUT NOT GLUCOCORTICOIDS ADMINISTRATION, INDUCES KNEE CARTILAGE LESIONS IN AN EXPERIMENTAL MODEL OF OSTEOPOROSIS IN RABBITS
Longitudinal Speckle Tracking Strain Abnormalities in Chagas Disease: A Systematic Review and Meta-Analysis.
BACKGROUND
Chronic Chagas cardiomyopathy (CCM) is ranked among heart failure etiologies with the highest mortality rates. CCM is characterized by alterations in left ventricular function with a typical and unique pattern of myocardial involvement. Left ventricle longitudinal speckle tracking strain is emerging as an important additive method for evaluating left ventricular function and risk of future cardiovascular events. This systematic review aimed to characterize the left ventricle (LV) longitudinal strain by speckle tracking patterns in the different stages of Chagas disease, compared to healthy controls.
METHODS
Searches in Medline, EMBASE, and LILACS databases (from inception to 20 May 2021) were performed. Articles written in any language that assessed patients with Chagas disease and reported any measures derived from the left ventricular strain by speckle tracking were included. Two reviewers independently selected the studies, extracted the data, and assessed the quality of evidence. Standardized mean differences (SMD) were pooled using random-effects meta-analyses.
RESULTS
Of 1044 references, ten studies, including a total of 1222 participants (CCM: 477; indeterminate form: 444; healthy controls: 301), fulfilled the selection criteria and were included in the final analysis. Patients with CCM had a significantly higher mean global longitudinal strain (GLS) value than indeterminate form (IF) patients (SMD 1.253; 95% CI 0.53, 1.98. I2 = 94%), while no significant difference was observed between IF patients and healthy controls (SMD 0.197; 95% CI -0.19, 0.59. I2 = 80%). Segmental strain analyses revealed that patients with the IF form of CD had significantly worse strain values in the basal-inferoseptal (SMD 0.49; 95% CI 0.24, 0.74. I2: 24%), and mid-inferoseptal (SMD 0.28; 95% CI 0.05, 0.50. I2: 10%) segments compared to healthy controls.
CONCLUSIONS
Our results suggest different levels of functional derangements in myocardial function across different stages of Chagas disease. Further research is needed to assess the prognostic role of LV longitudinal strain and other measures derived from speckle tracking in CD patients regarding progression to cardiomyopathy and clinical outcomes prediction
Detection of aluminium hydroxide-induced granulomas in sheep by computed tomography: A feasible approach for small ruminant lentiviruses diagnosis and research
Aluminium (Al) hydroxide use as adjuvant induces local formation of long-lasting subcutaneous granulomas in sheep. Macrophages within these granulomas have been identified as a new small ruminant lentivirus (SRLV) replication site in naturally infected animals. Diagnosis of Al hydroxide-induced granulomas in sheep is mostly based on postmortem observations but little information is available on in vivo detection. Computed tomography (CT) is used for studying these reactions in other animal species. To determine if CT could be a tool for in vivo diagnosis and research of subcutaneous Al hydroxide-induced granulomas in sheep. A retrospective survey on thoracic CT scans was performed on 46 adult sheep. Analysis included absence or presence, number and location of subcutaneous nodules. Thoracic CT scans and pathological studies were prescribed to two further sheep. Single or multiple subcutaneous nodules were detected in 26 (56.52%) sheep. One or two nodules per animal were most often observed (36.95%). Size ranged between 1.5 and 4.5 cm. Pre-contrast two-dimensional (2D) CT images showed focal or multifocal increases in subcutaneous tissue thickness. Post-contrast 2D CT images revealed hypointense areas in the centre. Histopathology indicated the presence of granulomas composed by a large number of activated macrophages, surrounding a central core of necrosis. Large intracytoplasmic Al-positive aggregates were demonstrated by lumogallion staining. CT is a useful tool to detect subcutaneous Al hydroxide-induced granulomas in vivo in sheep. CT provides a diagnostic and research tool that can be very useful in future works in Al hydroxide-induced pathology, SRLV infection, or both. © 2021 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd
Effect of specific amino acid substitutions in the putative fusion peptide of structural glycoprotein E2 on Classical Swine Fever Virus replication
AbstractE2, along with Erns and E1, is an envelope glycoprotein of Classical Swine Fever Virus (CSFV). E2 is involved in several virus functions: cell attachment, host range susceptibility and virulence in natural hosts. Here we evaluate the role of a specific E2 region, 818CPIGWTGVIEC828, containing a putative fusion peptide (FP) sequence. Reverse genetics utilizing a full-length infectious clone of the highly virulent CSFV strain Brescia (BICv) was used to evaluate how individual amino acid substitutions within this region of E2 may affect replication of BICv. A synthetic peptide representing the complete E2 FP amino acid sequence adopted a β-type extended conformation in membrane mimetics, penetrated into model membranes, and perturbed lipid bilayer integrity in vitro. Similar peptides harboring amino acid substitutions adopted comparable conformations but exhibited different membrane activities. Therefore, a preliminary characterization of the putative FP 818CPIGWTGVIEC828 indicates a membrane fusion activity and a critical role in virus replication
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