54 research outputs found
Forecasting bond returns using asymmetric regression and investment management
The first section of this research formulates the forecasting task important for managing investment portfolio as well as discusses certain statistical data. The second section is devoted to potential regressors frequently used to forecast risk premiums of bonds, this section extensively use the ideas presented in article [4]. The third section includes the research of asymmetry of relation between risk premiums and regressors. The fourth section is devoted to the investigation of applicability received results in practice
Vibrations generator with a motion converter based on permanent magnet interaction
The paper deals with a new type of vibrations exciters whose operation is based on the forces developed by permanent magnets interacting between input and output members. Classification and some diagrams of vibrations exciters are presented. Mathematical models of one-dimensional vibrations exciters are set up. In cases when mean velocities of the magnets of input member and output member are equal and when velocity of an output member magnet is lower than that of an input member, dynamics is studied by means of approximate analytic methods. More complicated cases are studied by means of numerical methods. Estimated dynamic characteristics of the system, its established peculiarities and properties make it possible to apply the mentioned exciters to some technological processe
Research of dynamics of rotary vibration actuators based on magnetic coupling
The article analyses a new type of a mechanical rotary oscillator – vibrator, the base of which is made of steady magnets. The scheme of a vibrator’s regulated power is submitted to excite the rotary oscillations of a turning frame. Some of the dynamical characteristics of a vibrator have been researche
Research of dynamics of rotary vibration actuators based on magnetic coupling
The article analyses a new type of a mechanical rotary oscillator – vibrator, the base of which is made of steady magnets. The scheme of a vibrator’s regulated power is submitted to excite the rotary oscillations of a turning frame. Some of the dynamical characteristics of a vibrator have been researche
Erratum to: genetic structure of fragmented southern populations of African Cape buffalo (Syncerus caffer caffer)
Erratum to: genetic structure of fragmented southern populations of African Cape buffalo (Syncerus caffer caffer)
Genetic structure of fragmented southern populations of African Cape buffalo (Syncerus caffer caffer)
peer reviewedBackground
African wildlife experienced a reduction in population size and geographical distribution over the last millennium, particularly since the 19th century as a result of human demographic expansion, wildlife overexploitation, habitat degradation and cattle-borne diseases. In many areas, ungulate populations are now largely confined within a network of loosely connected protected areas. These metapopulations face gene flow restriction and run the risk of genetic diversity erosion. In this context, we assessed the “genetic health” of free ranging southern African Cape buffalo populations (S.c. caffer) and investigated the origins of their current genetic structure. The analyses were based on 264 samples from 6 southern African countries that were genotyped for 14 autosomal and 3 Y-chromosomal microsatellites.
Results
The analyses differentiated three significant genetic clusters, hereafter referred to as Northern (N), Central (C) and Southern (S) clusters. The results suggest that splitting of the N and C clusters occurred around 6000 to 8400 years ago. Both N and C clusters displayed high genetic diversity (mean allelic richness (Ar) of 7.217, average genetic diversity over loci of 0.594, mean private alleles (Pa) of 11), low differentiation, and an absence of an inbreeding depression signal (mean FIS = 0.037). The third (S) cluster, a tiny population enclosed within a small isolated protected area, likely originated from a more recent isolation and experienced genetic drift (FIS = 0.062, mean Ar = 6.160, Pa = 2). This study also highlighted the impact of translocations between clusters on the genetic structure of several African buffalo populations. Lower differentiation estimates were observed between C and N sampling localities that experienced translocation over the last century.
Conclusions
We showed that the current genetic structure of southern African Cape buffalo populations results from both ancient and recent processes. The splitting time of N and C clusters suggests that the current pattern results from human-induced factors and/or from the aridification process that occurred during the Holocene period. The more recent S cluster genetic drift probably results of processes that occurred over the last centuries (habitat fragmentation, diseases). Management practices of African buffalo populations should consider the micro-evolutionary changes highlighted in the present study
Escape to Ferality: The Endoferal Origin of Weedy Rice from Crop Rice through De-Domestication
Ultrasound Use in Prehospital Setting
Aim: To find out the peculiarities of the use of ultrasound diagnostics in the prehospital setting. Objectives: 1. To determine whether ultrasound usage is feasible in prehospital setting 2. To determine the accuracy of ultrasound diagnostics in prehospital conditions 3. To find out if performed point-of-care ultrasound changes patient management 4. To find out what difficulties are encountered in using ultrasound in pre-hospital conditions Methods: A systematic review and analysis of the literature was performed according to the PRISMA methodology. The searches were performed on PubMed, ScienceDirect, Cochrane, and WebOfScience electronic databases using keywords and their synonyms. Articles not older than 10 years were included in the review and selected according to pre-established inclusion and exclusion criteria. Results: After conducting a search in databases 1736 entries were found. After rejecting duplicates, reviewing article titles and abstracts, 95 publications were selected for full article analysis. After full-text analysis, 15 articles were included in the systematic review. Six articles examined the peculiarities of lung ultrasound examination, two - the use of ultrasound during resuscitation, all the remaining articles did not focus on a specific area. The vast majority (14/15) of the articles analyzed the accuracy of prehospital ultrasound by assessing sensitivity, specificity, positive prognostic value, negative prognostic value, or kappa consensus level. Conclusions: 1. Ultrasound examination of a patient is a suitable diagnostic method in prehospital conditions. 2. The accuracy of ultrasound diagnostics varies depending on the area being studied and increases with repeated examination during the patient's care period. 3. Ultrasound examination of the patient provides useful information about his condition, helps to make important decisions related to the patient's care and helps to avoid unnecessary or harmful interventions. 4. The most common obstacles are weather and environmental conditions, which make it difficult to access the patient optimally. Ultrasound examination is more difficult and the quality of the examination is lower in patients who weigh more. Recommendations: Given the benefits of diagnostics for the patient, ultrasound examination of patients is also recommended in the pre-hospital phase
SCP paradigmos taikymas Baltijos šalių bankinių sektorių tyrimui
The aim of this paper is to conduct a research on Lithiuania‘s, Latvia‘s and Estonia‘s banking sector, to estimate the impact of concentration on the performance of a sector by applying SCP paradigm. Research period cover period from 2002 to 2012. The paper consists of three main parts. First part represents the theoretical framework of SCP paradigm and related empirical literature. Second parts provides substantiation for the research, hypothesis are formulated and methodology is designed. In the third part results of the research are provided. The results revealed that while impact of banking sectors concentration on profitability in Lithuania and Estonia is not significant, in Latvia there exists some evidence for traditional SCP hypothesis, i.e., banking sectors structure have a significant impact on performance of a sector.Šio darbo tikslas – ištirti Lietuvos, Latvijos ir Estijos bankų sektoriaus koncentracijos įtaką jų pelningumui pritaikant SCP paradigmą. Tyrimo laikotarpis apima 2002-2012 metus. Tyrimas susideda iš trijų pagrindinių dalių. Pirmoje dalyje pristatoma teorinė SCP paradigmos samprata ir supažindinama su empiriniais SCP paradigmos taikymo rezultatais. Antroje dalyje pateikiamas temos aktualumo pagrindimas atliekant objekto analizę, iškeliamos hipotezės ir sudaroma tyrimo metodologija. Trečiojoje dalyje pristatomi tyrimo rezultatai. Jie atskleidė, kad Lietuvos ir Estijos bankiniuose sektoriuose koncentracija neturi reikšmingos įtakos bankų pelningumui. Tuo tarpu Latvijos bankiniame sektoriuje nustatyta, kad sektoriaus koncentracija turi reikšmingos įtakos pelningumui, dėl to SCP hipotezė gali būti patvirtinta. Vytauto Didžiojo universiteta
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