Survey of Control Characteristics of Circular Air Dampers in Variable Air Volume Ventilation Systems

AbstractDue to the fact that importance of energy efficiency of building services is consistently growing also demand based VAV ventilation systems are becoming more common. Almost all available terminal VAV dampers on the market are single blade dampers, but is this damper configuration the most suitable for VAV functionality? The aim of this study was to test the control characteristics of the most widespread circular damper configurations. The results show that under typical operation conditions IRIS diaphragm type damper control characteristics are the most suitable for VAV functionality in means of linearity between damper opening position and relative air flow

The Impact of Revascularization in a Patient with Atypical Manifestations of Hypoperfusion

Publisher Copyright: © 2022 by the authors.Background and Objectives: Carotid revascularization is one of the most effective treatment options in patients with severe carotid artery stenosis causing hypoperfusion in basal ganglia. Atypical manifestations include hyperkinetic movements, noted as extremely rare. We report a case about a patient with 2-months-long complaints of Uncontrollable movements in his right side of the body subsided after carotid revascularization. Case presentation: A 71-year-old male was admitted to Pauls Stradins Clinical University Hospital with the main complaints of 2-months-long uncontrollable movements in his right hand and his right leg. When performing coordination tasks, slight inaccuracy was noted with the right-side extremities. Hyperkinetic movements—choreoathetosis in the right side of the patient’s face, arm, and leg—were seen. Computed tomography angiography revealed subocclusion in the proximal segment of the left internal carotid artery and 30% stenosis in the proximal segment of the right internal carotid artery. The patient was consulted by a vascular surgeon. Eversion endarterectomy of the left internal carotid artery was performed. The early postoperative period occurred without complications. The patient was discharged from the hospital 2 days after the surgery in good overall health condition. Two months later, choreoathetotic movements in his right side of the body had markedly decreased. No focal neurologic deficits were noted. Conclusions: Revascularization may be effective by eliminating emboli and stenosis, leading to hypoperfusion in watershed territories. A case of a 71-year-old male patient with the main complaints of 2-months-long uncontrollable movements in his right side of the body subsiding after carotid revascularization was demonstrated. It is vital to recognize atypical manifestations of hypoperfusion, associated with stenosis in internal carotid arteries, to early make a diagnosis, to perform an appropriate treatment, and to reduce the risk of cerebral infarction in the future, resulting in a longer high-quality life for the patient.publishersversionPeer reviewe

Tunneling luminescence in long lasting afterglow of SrAl2O4:Eu,Dy

The publication is prepared with the financial support of National Research Programme IMIS2.A long lasting (afterglowing) luminescent material SrAl2O4: Eu2+, Dy3+ was prepared by high temperature solid-state reaction method. The processes responsible for long lasting luminescence were studied by means of luminescence spectra, thermally stimulated luminescence and afterglow kinetics. Two processes are found to contribute in excited Eu 2+ creation – the thermally released electrons recombination and electron tunneling from trap to Eu3+. The possible scheme of long lasting luminescence mechanism is proposed.IMIS2; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Fatigue and associated factors in multiple sclerosis patients in Latvia

Sum mary. Back ground and ob jec tives. Fa tigue is one of the most com mon symp toms of mul ti ple scle ro sis (MS). The aim of this study was to de ter mine the pres ence of fa tigue in MS pa tients in Lat via and its re la tion to life style fac tors, neu ro log i cal dis abil ity and de pres sion. Ma te rial and meth ods. This cross-sec tional study in cluded 117 par tic i pants (44 pa tients with MS and 73 healthy con trol group). Ap plied re search in stru ments were: Ex panded Dis - abil ity Sta tus Scale (EDSS), Pa tient Health Ques tion naire (PHQ-9), Fa tigue Se ver ity Scale (FSS), and the gen eral ques tion naire for the col lec tion of socio-de mo graphic, life style hab its and clin i cal data con structed for the pur poses of this study. Re sults. Mean FSS score was 3.9±1.9 in MS group. 26 (59.1%) patients had FSS score of 3.8 or more and were clas si fied as a fa tigue group (MSF) while 18 (40.9%) patients had FSS of 3.7 or less and were clas si fied as a non-fatigue (MSNF) group. There was sta tis ti cally sig - nif i cant dif fer ence be tween MSF and MSNF groups con sid er ing PHQ-9 score (p=0.019), FSS score (p<0.001) and EDSS score (p<0.001). Sig nif i cant cor re la tions of fa tigue with depres sion (r=0.48, p=0.001), fa tigue with neu ro log i cal dis abil ity (r=0.49, p=0.001) and fatigue with smok ing (r=0.29, p=0.054) were con firmed. Con clu sions. Fa tigue is a com mon symptom in MS pa tients in Lat via. This study supports sig nif i cant as so ci a tion be tween fa tigue and clin i cal fac tors (dis abil ity, de pres sion) and mod i fi able life style fac tor – smok ingpublishersversionPeer reviewe

Carotid Artery Stenosis Correlation with Hyperhomocysteinemia in Stroke Patient Group: a Prospective Study

Introduction. Stroke is the second most common cause of death worldwide and one of the major causes of long-term disability. Carotid artery stenosis is an independent risk factor for ischemic stroke and related forms of atherosclerotic vascular disease. Aim of the Study was to examine plasma homocysteine (tHcy) levels in the stroke patient's group with significant carotid artery stenosis, to determine hyperhomocysteinemia correlation with degree of carotid artery stenosis. Materials and methods. This study was prospective and all patients (n=102) included in the study were hospitalized in Pauls Stradins Clinical University hospital in Clinic of Neurology with diagnosis of acute ischemic stroke. In the group of significant carotidal stenosis we included 48 patients with various degree of stenosis ranging from 50% to total occlusion. Evaluations of stenosis of extracranial carotid arteries were done by duplex ultrasonography method. The blood of these patients was tested for homocysteine level by ELISA (IMMULITE 2000). Results. Study did not demonstrated statistically significant difference between levels of tHcy in all groups. Mean homocysteine level was not significantly higher in the symptomatic carotid stenosis patient's group. Also there were no significant differences between levels of homocysteine in patient group with different degree of stenosis. Conclusions. We found no meaningful association between a high tHcy level and extent of carotid stenosis.publishersversionPeer reviewe

History of Academic Neurology in Latvia

Peer reviewe

X-ray excited luminescence of SrAl2O4:Eu,Dy at low temperatures

This research project was supported financially by ERDF Project No 1.1.1.1/16/A/182.ERDF Project No 1.1.1.1/16/A/182; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

The search for defects in undoped SrAl2O4 material

This research project was supported financially by ERDF Project No: Nr.1.1.1.1/16/A/182 .SrAl2O4:Eu,Dy is a very efficient long afterglow phosphor with wide range of possible applications. The luminescence properties and the possible luminescence mechanism of this material have been studied extensively, but there is almost no information available about the undoped material. Therefore, this article deals with the luminescence and thermally stimulated luminescence of an undoped SrAl2O4, revealing the possible defects that might be involved in the creation of the long afterglow in doped material. We conclude that undoped material exhibits some luminescence under X-ray irradiation in low temperature; close to room temperatures luminescence is almost fully thermally quenched in comparison to low temperatures. We can observe F and F2 center luminescence as well as trace metal luminescence in the emission spectrum. TSL glow curve yields the peaks that are close to those observed in material with Eu and Dy doping; therefore these peaks are clearly related to intrinsic defects. The peak at around 400 K, that is shifting with rare earth doping, might be due to dopant interaction with intrinsic defects.European Regional Development Fund Nr.1.1.1.1/16/A/182; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Functional and Structural Evaluation of Afferent Visual System in Multiple Sclerosis Patients

Publisher Copyright: © 2015 by Daina Pastare.There is insufficient information about the progress and variability of multiple sclerosis (MS). Afferent visual pathways are an appropriate MS clinical model. Optical coherence tomography (OCT) allows to perform precise measurements of axonal tissue in the retinal nerve fibre layer (RNFL). Visual evoked potentials (VEP) provide information about the functional status of visual pathways. The aim of our study was to use OCT and VEP to evaluate MS patients with and without optic neuritis (ON) history and to determine relationships between functional and structural changes. The cross-sectional study included 76 relapsing-remitting MS patients and 28 healthy controls. The lowest mean VEP N75/P100 amplitude was found in ON affected eyes (8.16 mkV, SD = 4.60). However, it was observed that the mean amplitude in patients without ON (M = 9.86; SD = 4.63) was by 4.64 mkV lower than in controls (p 0.001) between RNFLT and mean P100 latency. In summary, we found that deterioration in the visual system was not associated with the clinical ON episode. Regardless of ON symptoms in history, there exists correlation between functional and structural changes.publishersversionPeer reviewe

Recent progress in understanding the persistent luminescence in SrAl2O4:Eu,Dy

This work was conducted with the funding of Scientific Research Project for Students and Young Researchers realised at the Institute of Solid State Physics, University of Latvia [SJZ/2018/2].Ever since the discovery of SrAl2O4:Eu,Dy persistent afterglow material, that can intensively glow up to 20 h, the mechanism of long-lasting luminescence has been a popular area of research. The research is focused on discovering the mechanism of persistent luminescence in order to prolong the duration and intensity of afterglow in a controlled way. Although most researchers agree on the general things, there are still many unclarities and ambiguities to discuss upon. This review paper briefly sketches in the highlights of past research on the luminescence mechanism in SrAl2O4:Eu,Dy, mainly focusing on the research conducted in the past decade dedicated to clearing these ambiguities. This paper provides an overview of the latest persistent luminescence mechanisms offered by researchers.Latvijas Universitate SJZ/2018/2; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART