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PubMedDate not supplied

[Successions in the forest-steppe under climate changes: a modelling approach].

The paper represents an attempt to apply the general principles of modelling vegetation dynamics under climate changes to a study of the long-term vegetation dynamics in the forest-steppe zone of the European territory of Russia, with a purpose to forecast under special climatic scenarios. An original technique is used to construct a Markov chain as a model of vegetation succession. The technique emanated from gebotanic knowledge generalized as a scheme of successional transitions with estimates of the average duration for certain stages of succession. Whenever the knowledge related the stage duration to certain (climate-sensitive) factors of the environment, the fundamental potentiality arises to model the temporal course of succession as a function of a given scenario for how the key factors change. In the formal terms, the model represents a random chain of the Markov kind with a finite number of states and discrete time of transitions by the given scheme. Relative square distributions of succession stages under concern at any time moment (within an adopted scenario) appear as the model outcome (forecasts), as well as estimates of the attainment time for certain states of the vegetation in the territory under study. A method is proposed to describe dynamics of the phytomass production and stores (and the corresponding model trajectories are obtained) for a given scenario.

Adaptation, Physiological↗
PubMed2005

The climatic factors influencing the occurrence of dengue hemorrhagic fever in Thailand.

The aim of this study was to determine the independent effects of climatic factors: rainfall, temperature and relative humidity, on the occurrence of dengue hemorrhagic fever (DHF) in Thailand after adjustment for cyclical pattern. Data regarding monthly DHF reported cases by province, monthly rainfall, rain-days, average daily maximum temperature, average daily minimum temperature and average relative humidity, and mid-year province population from 1978 to 1997 (240 months) in 73 provinces were collected from various governmental departments. The general equation: Incidence of DHF = constant + trends + cyclic effects + climatic factors + noise was used as the statistical model. Out of 73 provinces examined, an increase in temperature was associated with a rise in the incidence of DHF in 9 provinces, whereas increased rainfall was associated with a decreased incidence of DHF in 7 provinces. Analysis by region shows that DHF incidence was negatively associated with extra rainfall in the southern region, but was positively associated with elevated temperatures in the central and northern regions. Variability in incidence was explained mostly (14.7% to 75.3%) by trend and cyclic change and much less (0.2% to 3.6%) by independent climatic factors.

Humans↗
PubMed2005

Climate and life-history evolution in evening primroses (Oenothera, Onagraceae): a phylogenetic comparative analysis.

Evolutionary ecologists have long sought to understand the conditions under which perennial (iteroparous) versus annual (semelparous) plant life histories are favored. We evaluated the idea that aridity and variation in the length of droughts should favor the evolution of an annual life history, both by decreasing adult survival and by increasing the potential for high seedling survival via reduced plant cover. We calculated phylogenetically independent contrasts of climate with respect to life history in a clade of winter-establishing evening primroses (sections Anogra and Kleinia; Oenothera; Onagraceae), which includes seven annuals, 12 perennials, and two variable taxa. Climate variables were quantified from long-term records at weather stations near collection localities. To explicitly account for phylogenetic uncertainty, contrasts were calculated on a random sample of phylogenetic trees from the posterior distribution of a Bayesian analysis of DNA sequence data. Statements of association are based on comparing the per-tree mean contrast, which has a null expectation of zero, to a set of per-tree mean contrasts calculated on the same trees, after randomizing the climate data. As predicted, increased annual aridity, increased annual potential evapotranspiration, and decreased annual precipitation were associated with transitions to the annual habit, but these trends were not significantly different from the null pattern. Transitions to the annual habit were not significantly associated with increases in one measure of aridity in summer nor with increased summer drought, but they were associated with significantly increased maximum summer temperatures. In winter, increased aridity and decreased precipitation were significantly associated with transitions to the annual habit. Changes in life history were not significantly associated with changes in the coefficient of variation of precipitation, either on an annual or seasonal (summer vs. winter) basis. Though we cannot attribute causality on the basis of a correlational, historical study, our results are consistent with the idea that increased heat and drought at certain times of the year favor the evolution of the annual habit. Increased heat in summer may cause adult survival to decline, while increased aridity and decreased precipitation in the season of seedling recruitment (winter) may favor a drought-avoiding, short-lived annual strategy. Not all of the predicted patterns were observed: the capability for drought-induced dormancy may preclude change in habit in response to summer drought in our study group.

Base Sequence↗
PubMed2005

The role of climate on Malaria Incidence Rate in four governorates of Yemen.

The aim of study was to investigate the role of climate on the Malaria Incidence Rates (MIR) in some regions in of Yemen. For such purpose, the monthly (MIR) were calculated from the records of the hospitals' laboratories and centers of the Malaria Rollback centers in the main cities of the governorates Hudeidah, Taiz, Sana'a and Hadramout for the period 1989-1998. The readings of the climatic factors (CF) particularly the average monthly temperature (T), relative humidity (RH), volume of rain fall (RF) and wind speed (WS) for the same period of time were also collected from different weather and climatic information resources. Descriptive statistics, simple linear regression and multiple linear regression techniques were used to analyse the relationship between MIR and CF. The analysis shows highly significant relationship between MIR and the CF in these regions of Yemen (p-value 0.001).

Climate↗
PubMed2005

[Study on the relations between epidemiology of respiratory syncytial infection in children and climate factors in Hangzhou].

OBJECTIVE: To study the epidemiolgy of respiratory syncytial virus (RSV) infection in children and its relations to climate factors in Hangzhou. METHODS: Monthly positive rate of RSV in pneumonia inpatients and climate factor including mean air temperature, mean relative humidity and rainy days per month were continuously observed for 3 years. Correlation analysis for RSV positive rate and these three climate factors were performed using partial correlation, and regression methods between the positive rate and significant factor was done. RESULTS: 13 642 cases were detected and 25.8% showed positive of RSV. The positive rate of RSV in children < or =1 years old, 1-3 years old, > 3 years old were 33.1%, 19.7% and 5.1% respectively with significant difference (chi2 = 763.7, P = 0.000). Rate of RSV infection was increased from December and kept in high level until May or April next year, but were varied at different years. Partial correlations between positive rate and rainy days, mean relative humidity, and mean air temperature per month were 0.32 (P= 0.066), -0.27 (P = 0.117) and -0.83 (P = 0.000) respectively. The regression equation of RSV positive rate and mean air temperature was: RSV positive rate (%) = 52.933 - 1.914 x mean air temperature (degrees C). CONCLUSION: RSV was one of the main factors causing of pneumonia in children while the highest infectious rate was in children < or =1 year old and infectious rate reduced along with the increase of age. Low air temperature was the main factor affecting the epidemiology of RSV. RSV was prevalent both in spring and winter in Hangzhou area.

Adolescent↗
PubMed2006

Impact of climate variability in the occurrence of leishmaniasis in northeastern Colombia.

Previous studies have shown that variation in the distribution of vectors associated to the transmission of Leishmania species may be related to climatic changes. However, the potential implications of these ecological changes in human health need to be further defined in various endemic populations where leishmaniasis carries a substantial burden of disease such as in Northeastern Colombia. Herein, we report the impact of El Niño Southern Oscillation climatic fluctuations during 1985-2002 in the occurrence of cases of leishmaniasis in two northeastern provinces of Colombia. During this period, we identified that during El Niño, cases of leishmaniasis increased, whereas during La Niña phases, leishmaniasis cases decreased. This preliminary data show how climatic changes influence the occurrence of leishmaniasis in northeastern Colombia and contributes to the growing body of evidence that shows that the incidence of vector-borne diseases is associated with annual changes in weather conditions.

Animals↗
PubMed1991

Indoor climate, air pollution, and human comfort.

The term sick building syndrome (SBS) is frequently used to describe a set of symptoms often reported by occupants of certain buildings. The symptoms are supposed to be direct or indirect consequences of an inadequate indoor climate. Typically, a majority of the occupants in these buildings complain, and the most frequent complaint is irritation of eyes, nose, and throat. Many different factors are known to be potential agents for the symptoms and no definitive causality has been identified yet. In consequence authors of publications on indoor air quality have been using the SBS term in different ways. A review of literature indicates that in supposed "sick buildings" only the prevalence of irritation of mucosal membranes and headaches seems to differ significantly from the prevalence in buildings considered to have a normal indoor climate. Volatile organic compounds (VOC) are known to have a potency to cause symptoms like those included in SBS. A dose-response relation for sensory reactions and mucosal irritation caused by volatile organic air pollutants is discussed, and a tentative guideline at 3 mg/m3 (about 0.9 PPM toluene equivalent) for the total volatile organic compounds (TVOC) is suggested for the nonindustrial indoor climates.

Air Pollution, Indoor↗
PubMedDate not supplied

[The effect of climatic treatment in the central highlands on the lipid, cortisol, renin and aldosterone content of the blood in patients with an acute myocardial infarct].

124 capable men who had survived large focal myocardial infarction underwent a 24-day course of treatment in a cardiological sanatorium situated in climatic conditions of low mountains (1600 m above the sea level). It was found that posthospital rehabilitation under conditions of low-mountain climate promoted antiatherogenic shifts in blood lipoproteins composition most distinct in patients with hyperlipidemias. Hydrocortisone and renin levels returned to normal values, physical performance rose. These positive trends make nonpharmacological rehabilitation and secondary prevention of coronary heart disease in low-mountain climate promising.

Adult↗
PubMed1978

Response of the respiratory tract of calves kept at controlled climatic conditions to bovine Herpesvirus 1 in aerosol.

Seven experiments with four calves each were conducted in which the calves spent at least four days of adaptation in an environmental chamber and then were subjected to climatic stress in the form of a number of constant ambient temperature and humidity combinations. On the second day of climatic stress the calves were individually exposed to measured numbers of infectious units of bovine herpesvirus 1 (BHV1, virus of infectious bovine rhinotrachetis) in aerosol. The calves were killed seven or eight days later. Mycoplasma were found in some nasal swabs and in one lung. Certain bacteria but no Pasteurella were often isolated from the lungs. Bovine herpesvirus 1 was isolated from chamber air and from most postinoculation nasal swabs, tracheas and lungs. The number of macro- and microscopic lesions did not appear to be influenced by the climatic conditions of the experiments. The histopathological changes in epithelium at all levels of the respiratory tract were described in detail.

Animals↗
PubMed1990

[The stress process of hot-dry climatic conditions in a simulation chamber].

On the basis of investigations in the potash mining industry of GDR were formulated the starting conditions for experiments in a simulation chamber. The results of the experiments in a climatic chamber to complex dry-hot mining climatics are published and compared with hitherto existing results. Comprehensions to work load limits for dry-hot climatic conditions are established.

Body Temperature Regulation↗
PubMed1988

Plant life in cold climates.

Structural and functional features of plants from cold regions such as high mountain and tundra environments are characterized. Cold climates are not necessarily cold for plants at all times and influences of plant-growth form on canopy climate are substantial. Extreme low temperatures can cause temporal cessation of metabolic processes or partial tissue losses, but rarely represent an existential problem for plants native to cold regions. Low temperatures induce drastic changes in plant physiognomy and leaf anatomy, but dry matter allocation to the different plant compartments does not show a uniform trend. This suggests that generalizations of optimization and adaptation theories are not appropriate in this respect and that the functional importance of carbohydrate budgets is commonly over-estimated. Inconsistent with widespread beliefs, photosynthetic capacity in plants from cold regions is not essentially different from that in temperate regions, when comparable life forms are considered. Prevailing leaf temperatures exert minor limitations to seasonal photosynthetic carbon gain. Low temperatures come into play primarily in two ways: indirectly, via the length of the growing season and perhaps mineral nutrient availability, and directly, through influences on the growth process per se. Inherited slow or temporally restricted growth resembles an evolutionary response to long-term expectations of low resource availability. Within these genetic constraints the mitotic rate seems to be an essential point of action where low temperature determines the growth of an individual under respective local climates. Evidence is provided to support this view of an overruling significance of developmental processes in plant performance under cold conditions.

Climate↗
PubMed1987

[Effect of the climate of the Anapa health resort on the effectiveness of treatment of chronic aspecific lung diseases in adolescents].

The results of examination of 2144 adolescents with bronchial asthma and chronic bronchitis coming to the health resort area of the Black Sea coast of the Caucasus from various regions of the USSR showed a significant effect of the climatic and weather factors on the efficacy of sanatorium treatment. Change of climatic zones resulted in the reduction of therapeutic efficacy due to dysadaptation reactions of the body necessitating stricter indications for a differentiated selection of adolescents coming from contrast climatic zones of the Urals, Siberia and the Far East.

Adolescent↗
PubMed1986

[Comparative study between cerebral seizure and the climatic trend in the province of Brescia].

This study seeks to identify which of the various climatic parameters is the most significant causative factor for the onset of cerebral ictus or TIA in subjects clinically "at risk". The research was conducted in the province of Brescia, where it was discovered that the most stressful climatic factor was a warm, dry south-westerly wind (SW). It was postulated that such climatic conditions may favour platelet aggregation by means of an increase in the charge of positive ions in the air.

Cerebrovascular Disorders↗
PubMedDate not supplied

[Body function in nutrition with a diet made up of canned products during acclimatization to a hot climate].

Eight physically trained male volunteers living in tropical countries were examined. Being under high physical load they were given the diet (for 3 weeks) containing food concentrates and canned food with a caloric value of 3860 calories. Energy expenditures amounted to 3600-4100 kcal/day. According to the physiological data the central and peripheral nervous systems and higher nervous activity remained unchanged throughout the entire observation period. As shown by the PWC170 test, the orthostatic stability and exercise tolerance were lowered at the initial period of the living in hot climate. Subjectively this was manifested by excessive fatigue toward the end of the working day. All the characteristics under study returned to normal by the 10th day of living in hot climate. The data obtained indicate that under the conditions of hot climate and appreciable physical loading, it is necessary to take into account the changes in body function in order to improve the diet for the people to be able to get adapted to the conditions in question.

Acclimatization↗
PubMed1979

As to the influence of climate on head form.

In two quite different geographical regions--Moçambique and Hierro (an island of the Canaries)--observations have been made which point to an influence of climatic conditions on head dimensions: In localities of higher altitude or/and with colder climate maximum head breadth, minimum frontal breadth and auricular height proved to show higher dimensions compared with localities of milder (more hot) climate.

Angola↗
PubMed1983

Relation between geographical distribution of liver cancer and climate-aflatoxin B1 in China.

This paper analyses, for the first time in China, the relationship between the data on climate (temperature and humidity) in the country, aflatoxin, hepatitis B and primary liver cancer mortality, by using the methods of geographical epidemiology and generalized factor analysis, and also approaches the characteristics of the geographical distribution of liver cancer in China from a climate-mould viewpoint. The authors come to the conclusion that climate is an important environmental condition that determines the differences in the distributions of liver cancer in different areas, and that aflatoxin B1 is one of the main carcinogenic factors of liver cancer.

Aflatoxin B1↗
PubMed1980

[The influence of climatic treatment on INT-reductase activity in leukocytes of patients with asthma bronchiale (author's transl)].

The mean values of INT-reductase in nonstimulated (nonphagocytising) polymorphs as well as in polymorphs stimulated by zymosan were higher in patients with asthma bronchiale than in a group of clinically healthy volunteers of the same age. The activities of INT-reductase in the leukocytes of patients with asthma bronchiale decreased during a climatic treatment in the high mountain conditions of Strbské Pleso (altitude 1,350 m) and after 3-5 weeks of treatment they reached the normal values ascertained in healthy volunteers. When the climatic treatment ended and the patients returned back to Bratislava, the ability of their leukocytes to reduce INT gradually increased to the levels which were found before the treatment. The changes in the activity of INT-reductase are statistically significant and may be used as an objective criterion for the control of climatic treatment and for its rational dosage.

Adult↗
PubMed1980

[Climatic chambers for animals].

The KTLK 20 000 is a climatic thermolight chamber developed for plant research by VEB Nema Netzschkau. It was modified into a climatic thermal chamber for animals by the Institute of Applied Livestock Hygiene in cooperation with the above manufacturers. Two climatic chambers are in operation. They are different in size. Their structure and working principle are described.

Animals↗