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The authors have elaborated a formula to calculate the average number of times an anopheline parous female bites in one day ("L") according to its gonotrophic cycle and more specially to its behaviour before and after oviposition (parameters "alpha" and "A". The formula was applied to Anopheles gambiae observed at Djoumouna village (L = 0.40) and to Anopheles nili observed at M'Pola village (L = 0.30). The value obtained has then to be multiplied by the anthropophilic index to obtain the "a" parameter of MacDonald (1957) when studying malaria transmission in a village. On the other hand such a formula allowed a better evaluation of biting frequency of a vector, thus of risks of transmission of diseases, according to the respective situation of human houses and water storages. An important point which ahs to be born in mind when planning artificial permanent reservoirs.  相似文献   

3.
The intentional introduction of exotic species can increase the level of local biodiversity, enrich people's material lives, and bring significant social and economic benefits that are also the symbols of human progress. However, along with the frequent intercourse among countries and regions, the frequency of uncontrolled crossregional migration of species is increased and there is a lack of scientific management strategy for the intentional introduction of exotic species. Exotic species invasion, which is behind habitat fragmentation, has become the second largest threatening factor to the maintenance of the global-scale level of biological diversity. Exotic species invasion can destroy the structure of an ecosystem, disturb the economic life of a society, and do harm to human health. In this paper, the authors review some of the ecological explanations for issues such as "what causes or mechanisms have led to the successful invasion of exotic species", including the "ideal weeds characteristics", "biodiversity resistance hypothesis", "enemies release hypothesis", "evolution of increased competitive ability hypothesis", "niche opportunity hypothesis", and "novel weapon hypothesis". The authors also analyze and evaluate the background and theoretical basis of the hypotheses, providing explanations for some phenomena, as well as the deficiencies of these explanations.  相似文献   

4.

Background

Bioinformatics is an interdisciplinary field at the intersection of molecular biology and computing technology. To characterize the field as convergent domain, researchers have used bibliometrics, augmented with text-mining techniques for content analysis. In previous studies, Latent Dirichlet Allocation (LDA) was the most representative topic modeling technique for identifying topic structure of subject areas. However, as opposed to revealing the topic structure in relation to metadata such as authors, publication date, and journals, LDA only displays the simple topic structure.

Methods

In this paper, we adopt the Tang et al.’s Author-Conference-Topic (ACT) model to study the field of bioinformatics from the perspective of keyphrases, authors, and journals. The ACT model is capable of incorporating the paper, author, and conference into the topic distribution simultaneously. To obtain more meaningful results, we use journals and keyphrases instead of conferences and bag-of-words.. For analysis, we use PubMed to collected forty-six bioinformatics journals from the MEDLINE database. We conducted time series topic analysis over four periods from 1996 to 2015 to further examine the interdisciplinary nature of bioinformatics.

Results

We analyze the ACT Model results in each period. Additionally, for further integrated analysis, we conduct a time series analysis among the top-ranked keyphrases, journals, and authors according to their frequency. We also examine the patterns in the top journals by simultaneously identifying the topical probability in each period, as well as the top authors and keyphrases. The results indicate that in recent years diversified topics have become more prevalent and convergent topics have become more clearly represented.

Conclusion

The results of our analysis implies that overtime the field of bioinformatics becomes more interdisciplinary where there is a steady increase in peripheral fields such as conceptual, mathematical, and system biology. These results are confirmed by integrated analysis of topic distribution as well as top ranked keyphrases, authors, and journals.
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5.
A screening of antitetanic antibody (AcAT) carriers has been carried out in 4770 blood donors. The percentage of "positive" subjects (with a rate of AcAT greater than or equal to 5 U.I./ml according to Laurell's method) is relatively high: 6,62%. The aim of a statistical study is to find out the distribution of AcAT carriers according to different factors: the chi 2 test allows us to conclude that the relation between the frequency of "positive" AcAT carriers and the blood groups is not significant but there is a significant connection between the frequency of "positive" AcAT carriers, sex and age. Our conclusions agree with those of authors having performed the study after vaccination. Our study has a double advantage: it allows us to know the vaccination state of the blood donors before any vaccination and allows the collecting of "positive" serum samples without having to wait for the vaccination.  相似文献   

6.
Using enlarged mechanical models of the cochlea and true stimuli sinusoidal or transient, the authors give photographics documents which point out in objective way the "basilar" membrane responses. With pure tones, the membrane vibrates along its entire length no matter what the frequency. With transients, there is a maximum displacement in varying sites but always near the base.  相似文献   

7.
In order to identify the endocrine cell types in various parts of the Ruminant gut, we have applied ultrastructural, both morphological and cytochemical, techniques, in parallel to the histochemical ones, to study the rectal mucosa of the adult Ox. In these studies we show that: "EC" cells, of the intestinal type, contain predominantly pleiomorphic granules, which are very electron dense and heavily reactive to "Masson" and "Grimelius" methods; "L" cells are recognizable by their numerous granules, which are fairly homogeneous in shape and osmiophilia. They do not react with "Masson" and are weak or negative to Grimelius s reaction. These granules occur near to others that are less dense, unreactive to "Masson", and that contain an argyrophilic matrix, with an eccentric electron dense core, which does not react with silver; "F-like" cells contain granules which are variable in shape, size and osmiophilia. They are unreactive to "Masson" and weak or unreactive to Grimelius silver; "H" cells contain few, small and uniformly osmiophilic granules. These are unreactive to "Masson" and uniformly reactive to "Grimelius". Our data suggest that the morphology, frequency and distribution of the cell types we have identified in the mucosa of the bovine rectum correspond with those reported in large intestine and rectum of Monogastrics, as by other authors described.  相似文献   

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The dangerous effects of phototherapy have been matter of discussion in recent years. In order to evaluate its in vitro action on the human DNA, the authors have performed the karyotypic analysis on 20 cultures of lymphocytes. In different times 16 cultures have been exposed to the action of a "blue light" fluorescent lamp, commonly used for the treatment of neonatal jaundice. The authors have not evidenced any morphological or numerical change of the karyotype in any of the cultures.  相似文献   

10.
The authors consider the spondylolysis a polyetiologic abnormality with an important part of congenital factors in its origin. The frequency of spondylolysis can be considered a feature characterizing a population. This opinion is confirmed by finds in skeletal materials from old Slavonic and Slavonic-Avaric cemeteries. The frequency of spondylolysis in the Slavonic part is significantly lower than in the Slavonic-Avaric part of the materials. The share of unilateral spondylolysis is also different (15 and 7%) when comparing these two population groups, but statistically insignificant. The so-called "combined" type of spondylolysis is, however, significantly higher in the number of unilateral cases of spondylolysis than in the bilateral ones.  相似文献   

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Vibrations of a homopolymer DNA with localized hydrogen bond defects have been examined using the recently developed decaying mode theory for long-chain polymers with local structural defects. For a poly(dA)-poly(dT) homopolymer having perturbed hydrogen bonds in one base pair, a localized mode at 63.2 cm-1 has been found. This mode has a very nearly pure H-bond stretch or "breathing" character, although the backbones do not separate. This agrees in frequency with a similar result found by other authors using a different approach. We search the full microwave frequency range for other local modes for several models of weakened H bonds. Besides the local mode with breathing characteristics, local modes with other characteristic motions were found, but only for asymmetrically perturbed bonds. We find in general that local modes are not very robust, requiring quite specific, narrow ranges in parameter space. They are also not abundant, there being only three in our most prolific model.  相似文献   

13.
The ampullae ofLorenzini of elasmobranchs have a high sensitivity to temperature, as has been found bySand (1938) andHensel (1955) in single fibre preparations. Rapid cooling results in a steep, although temporary increase in impulse frequency; rapid warming is followed by a short and temporary inhibition of discharges. This behaviour very closely resembles that of the “cold” receptors of warm blooded animals. During experiments with isolated ampullae ofLorenzini of the infra- and supraorbital group ofScyllium canicula, we found in two animals some ampullae with an opposite response to temperature changes: rapid cooling inhibited the discharges of the ampullae, while rapid changes to warmth initiated a temporary increase in impulse rate. In some of the ampullae a kind of “adaptation” after fast temperature changes was observed which was also different from what has been described by other authors. The high dynamic response after rapid cooling was followed by a strong diminution in discharge rate. Only after several minutes the impulse frequency again rose to a new and constant level. With rapid warming the behaviour of the spike rate was the mirror image: initially, the frequency dropped to low values but then rose again to a level which was higher than before warming. After this maximum the discharge role fell to a constant frequency. From the results it may be concluded that the localization of the ampullae might be of importance for the “specific” function of the receptor as well as for the differentiation of the peripheral stimulus patterns.  相似文献   

14.
The coherency characteristics of the brain electrical activity were studied in two groups of subjects: 1) with high and 2) low indexes of "emotional ear" (an ability to successfully recognize emotions in the speech). Comparison of the coherency links between two groups of subjects permitted the authors to make a conclusion that the persons of the first group had a much lower coherency level, especially in the alpha- and gamma-rhythms. The subjects of the second group were characterized by the opposite tendency: an increase in coherent links on the majority of frequency bands.  相似文献   

15.
The phenomenon of trunk twisting in Pinus sylvestris L. and Picea obovata Ldb. during a vegetation period has been revealed and described by direct measurements. The frequency of this phenomenon, magnitude, and direction of twists and their 2-year dynamics have been studied on five sample plots located in different forest-growing conditions. The average rotation angle is 0.2°–0.5°, while its maximum values reach 1.3°–1.7°. These characteristics depend on forest type and weather conditions. Next year more, than half of the trees change their twisting direction to the opposite one, whereas 8–19% of pine trees keep it unchanged. Based on an analysis of our results and the data of other authors, a qualitative model of morphogenetic processes has been proposed to explain the mechanism of this phenomenon.  相似文献   

16.
Agrobacterial Transformation of Uninjured Plants   总被引:1,自引:0,他引:1  
The capacity for agrobacterial transformation (using Agrobacterium tumefaciens strain GV3101 with the activated vir genes) was investigated in uninjured seedlings of tobacco (Nicotiana tabacum L.), rice (Oryza sativa L.), and wheat (Triticum aestivum L.) along with the effect of various factors on the frequency of tobacco seedling transformation. Transformed cells were found at the base of the rice leaf sheath and in the upper part of tobacco leaves, whereas they were absent from wheat leaves. Illumination and temperature, which were below and over the optimum, were the factors limiting agrobacterial transformation of uninjured plants. Preincubation of tobacco seedlings in 100 M ABA, 10 mM EGTA, and 0.1 mM colchicine decreased the frequency of agrobacterial T-DNA penetration into plant cells. The authors conclude that transformation occurs predominantly in young growing cells, and its frequency is related to the state of stomata and plasmodesmata of the target plant cells. The elements of the cytoskeleton probably participate in T-complex transport.  相似文献   

17.
Spectral and time characteristics of forced expiratory sound, recorded in the trachea, were analyzed in 96 subjects. Sick and healthy subjects and the risk group demonstrated substantial differences in the acoustic parameters (total sound duration, vortex stoppage duration, and emergence of spectral components with high frequency and narrow band at the end of an expiration). The authors suggest and substantiate acoustic criteria of the bronchial patency disorder, assuming on this basis that such disorders are more common in patients with chronic nonobstructive bronchitis (70.8%) and subjects at risk for chronic obstructive pulmonary diseases (45.4%) than is demonstrated by conventional functional methods.  相似文献   

18.
Response characteristics of human operators in manual pursuit tracking with auditory input are investigated. The human operator hears in his left ear a sound whose frequency varies in proportion to an external random signal. At the same time, he hears in his right ear another sound whose frequency varies in proportion to the angle of a control lever of a potentiometer. The operator controls the angle of the lever so that the frequencies of the sounds in both ears remain as close as possible. The dynamics of the human operator is studied by assuming a manmachine system whose input is the external signal and whose output is the voltage of the potentiometer. A learning identification method proposed by one of the authors is used to calculate the weighting function of the man-machine system, which is displayed on a CRT screen in real time. During the tracking task, the skin potential activity (SPA) is measured as an index of arousal of the operator.  相似文献   

19.
The authors present the results obtained in the survey of graduates from the sanitary and hygienic departments of 4 medical institutes of the Ukrainian SSR carried out in a special pedagogical experiment with the aim to determine the "survival" of their knowledge in epidemiology. As a result, variations in the stability of knowledge in different branches of this discipline, especially in disinfection, the problems requiring the integration of knowledge in epidemiology and hygiene (municipal and alimentary), etc., have been revealed. The authors propose some measures for the improvement of teaching.  相似文献   

20.

Background

Litigation documents reveal that pharmaceutical companies have paid physicians to promote off-label uses of their products through a number of different avenues. It is unknown whether physicians and scientists who have such conflicts of interest adequately disclose such relationships in the scientific publications they author.

Methods and Findings

We collected whistleblower complaints alleging illegal off-label marketing from the US Department of Justice and other publicly available sources (date range: 1996–2010). We identified physicians and scientists described in the complaints as having financial relationships with defendant manufacturers, then searched Medline for articles they authored in the subsequent three years. We assessed disclosures made in articles related to the off-label use in question, determined the frequency of adequate disclosure statements, and analyzed characteristics of the authors (specialty, author position) and articles (type, connection to off-label use, journal impact factor, citation count/year). We identified 39 conflicted individuals in whistleblower complaints. They published 404 articles related to the drugs at issue in the whistleblower complaints, only 62 (15%) of which contained an adequate disclosure statement. Most articles had no disclosure (43%) or did not mention the pharmaceutical company (40%). Adequate disclosure rates varied significantly by article type, with commentaries less likely to have adequate disclosure compared to articles reporting original studies or trials (adjusted odds ratio [OR] = 0.10, 95%CI = 0.02–0.67, p = 0.02). Over half of the authors (22/39, 56%) made no adequate disclosures in their articles. However, four of six authors with ≥25 articles disclosed in about one-third of articles (range: 10/36–8/25 [28%–32%]).

Conclusions

One in seven authors identified in whistleblower complaints as involved in off-label marketing activities adequately disclosed their conflict of interest in subsequent journal publications. This is a much lower rate of adequate disclosure than has been identified in previous studies. The non-disclosure patterns suggest shortcomings with authors and the rigor of journal practices. Please see later in the article for the Editors'' Summary  相似文献   

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