The regulation of malaria parasitaemia: parameter estimates for a population model

SUMMARYClassical studies of non-immune individuals infected with Plasmodium falciparum reveal that the infection may be regulated for long periods at a relatively stable parasite density, despite the enormous growth potential of a parasite that continually replicates within host erythrocytes. This suggests that the parasite population may be controlled by density-dependent mechanisms, and in theory the most obvious of these is competition between parasites for host erythrocytes. Here we evaluate the role of this mechanism in the regulation of parasitaemia, by modelling the basic population interaction between parasites and erythrocytes in a form that allows all the essential parameters to be estimated from clinical data. Our results show that competition cannot account for the total regulation of P. falciparum, but when combined with immune mechanisms it may play a more important role than is generally supposed. Further analysis of the model indicates that in the long term, parasite replication at low parasite densities can contribute significantly to the high degree of anaemia observed in natural infection, a conclusion which is not obvious from simple clinical observation.

Download Full-text

Export of Services by Kazakhstan: Trends, Structure, Growth Potential

Russia and New States of Eurasia ◽

10.20542/2073-4786-2021-4-128-144 ◽

2021 ◽

pp. 128-144

Author(s):

V. Dodonov

Keyword(s):

Foreign Trade ◽

Significant Contribution ◽

Growth Potential ◽

Trade In Services ◽

Advanced Development

The article examines the situation with the export of services from Kazakhstan. The dynamics of the volume and relative parameters of export of services, its structure by main types and geographical areas are analyzed. Long-term tendencies of foreign trade in services are revealed, the role of export of services in the total volume of exports of Kazakhstan is compared with other countries and their groups. The features of the export of the two largest types of Kazakhstani export of services – transport and travel are considered in detail. The directions of stimulating export of certain types of services that can make a significant contribution to increasing exports and ensure the advanced development of non-resource foreign trade are substantiated.

Download Full-text

Bluetongue in Europe and the role of wildlife in the epidemiology of disease

Polish Journal of Veterinary Sciences ◽

10.1515/pjvs-2015-0060 ◽

2015 ◽

Vol 18 (2) ◽

pp. 455-461 ◽

Cited By ~ 7

Author(s):

W. Niedbalski

Keyword(s):

Roe Deer ◽

Natural Infection ◽

Carrier State ◽

Clinical Disease ◽

Domestic Sheep ◽

African Buffalo ◽

Wild Sheep ◽

South Eastern Europe

Abstract The article reviews a current bluetongue (BT) epidemiological situation in Europe, BT restricted zones and the role of wild ungulates as a reservoir for bluetongue virus (BTV) and its transmission. BT has been eradicated from central and northern Europe, however it is still circulating in some regions of southern and south-eastern Europe. According to the recent information of the Directoriate General for Health and Consumer Affairs (DG SANCO) disease caused by BTV1 was spreading at the beginning of 2014 in Corsica (France). Moreover, four BTV1 cases were noticed in the west Spain (Cáceres province), 59 BTV4 outbreaks in south Spain (Andalusia), 10 in the region of Algarve in Portugal and about 200 outbreaks of BTV4 in Greece (Peloponesse and Evros regions). On 4th July the first outbreak of BTV4 was also confirmed at the south Bulgarian border and by 5th September 2014 disease was noticed in 21 of 28 administrative districts of Bulgaria. In August 2014 the BTV4 disease was reported in south-east of Romania and as for 8th September 184 outbreaks of BT were confirmed in 17 counties of this country. As of 3 September 2014 in Europe there has been fourteen BT-affected zones, in different regions of Italy, Spain, Portugal, Cyprus, Malta, France (Corsica), Greece, Bulgaria and Romania. Most species of wild ruminants and camelids are susceptible to BTV infection, although frequently asymptomatically. Wild sheep, bighorn and mouflon, are susceptible to BTV infection and can develop fatal clinical disease, as do domestic sheep. Experimental or natural infection of antelope, wapiti, musk, ox, bison, yak, white-tailed deer and African buffalo also produced clinical disease, whereas blesbock, mountain gazelle, roe deer, red deer and Eurasian elk did not show clinical sign after natural or experimental infection and infection was recognized by the presence of BTV viral RNA or specific antibodies. The wildlife due to the long-term carrier state may act as a reservoir for BTV and play an important role in its transmission.

Download Full-text

The Role of Net Working Capital in the Financing of the Operating Activities of Mining Companies

Inżynieria Mineralna ◽

10.29227/im-2021-01-16 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Maria SIERPIŃSKA ◽

Małgorzata KOWALIK

Keyword(s):

Raw Materials ◽

Working Capital ◽

Short Term ◽

Excess Liquidity ◽

Current Asset ◽

Relationship Of ◽

High Degree ◽

Operating Activities

The paper examines how companies’ net working capital is used to finance their operating activities. Net working capital is a source oflong-term financing (equity and long-term external capital) and is more expensive than financing through short-term sources, henceits rational use has a significant impact on the efficiency of companies’ operations. The computed level of net working capital is usedto calculate ratios enabling companies to control this capital. The ratios indicate the relationship of net working capital to currentassets, to the sum of accounts receivable and short-term investments, to cash and cash equivalents, and sales revenues. Based on thesecalculations of the relationships, an assessment was made of net working capital engagement in the financing of operating activities inmining companies. These companies maintain a high degree of current asset financing through long-term capital. In mining companieswith diverse mining activities, the level of current assets financing through long-term capital is higher than in coal mining companies.This is due to the maintenance of a higher level of inventories of extracted raw materials, the distance of outlets from the place ofextraction and the method of transport used. Based on the ratio of net working capital to cash and cash equivalents, it was found thatsome companies were overly liquid. Cash balances significantly exceed the value of this capital over a period of three to four years. Asurplus of cash over net working capital in the short term cannot be treated as excess liquidity, as it is the due to flexible managementof this capital.

Download Full-text

Pseudopelade of Brock: clinical observation

RUDN Journal of Medicine ◽

10.22363/2313-0245-2020-24-4-368-372 ◽

2020 ◽

Vol 24 (4) ◽

pp. 368-372

Author(s):

S. K. Ryabov ◽

O. A. Mesnyankina

Keyword(s):

Histological Examination ◽

Rare Variant ◽

Hair Loss ◽

Clinical Observation ◽

Detailed Examination ◽

Close Attention ◽

Scarring Alopecia ◽

Skin Biopsies

The article presents clinical observation of a rare variant of scarring alopecia - pseudopelade Brock. The presented case demonstrates the important role of detailed examination and close attention to patients with long-term foci of hair loss in the absence of positive dynamics from the therapy, maintaining clinical alertness and conducting a broad differential diagnostic search to exclude rare dermatoses, and also confirms the need for histological examination of skin biopsies to verify the diagnosis.

Download Full-text

Does Trade Liberalisation Hurt Nigeria’s Manufacturing Sector?

International Journal of Economics and Finance ◽

10.5539/ijef.v8n6p175 ◽

2016 ◽

Vol 8 (6) ◽

pp. 175

Author(s):

Callistus Ogu ◽

Chibueze Aniebo ◽

Paul Elekwa

Keyword(s):

Trade Liberalization ◽

Competition Policy ◽

Manufacturing Sector ◽

Parameter Estimates ◽

Export Trade ◽

Medium Term ◽

Real Potential ◽

Short Run

<p>This study examines the role of trade liberalization in the growth of manufacturing output in Nigeria, focusing on the short to medium term period while not ignoring the very important long term on which most studies have focused. Data for the period 1980 to 2013 were obtained from CBN and WDI, with which parameter estimates were extracted for the short to medium term using the error correction mechanism. Trade liberalization was found to hurt manufacturing output in the short run although it showed a real potential to boost it in the long term. An overhaul of competition policy was recommended with a view to establishing Neutral Status in manufacturing export trade.</p>

Download Full-text

Growth Volatility and Economic Growth in Brazil

10.1093/oxfordhb/9780190499983.013.17 ◽

2018 ◽

Author(s):

Jorge Arbache ◽

Sarquis J. B. Sarquis

Keyword(s):

International Standards ◽

Growth Potential ◽

Limited Growth ◽

Term Outcome ◽

Long Term Outcome ◽

Substantial Growth ◽

International Convergence ◽

High Degree ◽

Growth Volatility

One of the most puzzling pieces of evidence surrounding Brazil’s economic performance is that, despite the country’s ability to grow at high rates, its long-term growth has been disappointing. Behind this deficient long-term outcome, Brazil shows a high degree of growth volatility. It has experienced substantial growth booms and busts as measured by international standards. This chapter provides an analysis of growth volatility and its impact on Brazil’s growth performance and long-term trajectory. Particular attention is given to its long-term underperformance, its macroeconomic regularities, and the possible causes and implications of its limited growth potential and degree of international convergence.

Download Full-text