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1.

Objective

Sex-ratio at birth in families with previous girls is worse than those with a boy. Our aim was to prospectively study in a large maternal and child unit sex-ratio against previous birth sex and use of traditional medicines for sex selection.

Main Outcome Measures

Sex-ratio among mothers in families with a previous girl and in those with a previous boy, prevalence of indigenous medicine use and sex-ratio in those using medicines for sex selection.

Results

Overall there were 806 girls to 1000 boys. The sex-ratio was 720∶1000 if there was one previous girl and 178∶1000 if there were two previous girls. In second children of families with a previous boy 1017 girls were born per 1000 boys. Sex-ratio in those with one previous girl, who were taking traditional medicines for sex selection, was 928∶1000.

Conclusion

Evidence from the second children clearly shows the sex-ratio is being manipulated by human interventions. More mothers with previous girls tend to use traditional medicines for sex selection, in their subsequent pregnancies. Those taking such medication do not seem to be helped according to expectations. They seem to rely on this method and so are less likely use more definitive methods like sex selective abortions. This is the first such prospective investigation of sex ratio in second children looked at against the sex of previous children. More studies are needed to confirm the findings.  相似文献   

2.
The latency of a simple psychophysiological (visual motor) response (SPPR) was studied as dependent on the waiting time, which was the period between the previous response to a subsequent stimulus and was varied from 1 to 3000 ms. An ordinal approximation was used for the resulting monotonic dependence. The latency of the simple psychophysiological response at shorter intervals between the previous response and a subsequent stimulus was observed to be far greater than at longer intervals. The latency decreased with the increasing waiting time until 3–4 s after the previous response. The decrease included at least two components. The components were found to be interdependent. The decrease in latency was assumed to result from autoinhibition due to the previous response.  相似文献   

3.
A determination of some of the factors that predict the outcome of contests between male tree lizards, Urosaurus ornatus, was made using logistic regression modelling on matched-pair data. Two-day-long encounters were staged between pairs of males differing in size (snout-vent length and mass), previous contest status (previous winners and previous losers), and coloration (dorsal coloration during their previous contest and throat coloration, a fixed trait). Mass proved to be the best single predictor of contest outcome, resulting in an 80% correct classification rate for predicting winners and losers, far better than the less than 57% correct classification rate for snout-vent length. Previous social status (winner or loser) also was a powerful single predictor of contest outcome with a 793% correct classification rate, as was previous dorsal coloration (76.7%). When combined, mass and previous status produced the strongest combination of predictors with a better than 86% correct classification rate. Contrary to several previous studies, which implicated throat coloration as an important status signal of dominance, our results failed to show that throat coloration is a strong predictor of contest outcome. Possible reasons for this discrepancy with earlier findings are discussed. The logistic regression models also allow prediction of the magnitude of difference in mass between two contestants for there to be an equal chance of winning, given a second asymmetry in contest predictors.  相似文献   

4.
The expression for the form of organisms in terms of their biological functions, outlined in a previous paper, is carried out somewhat more in detail. Making definite assumptions about functions left arbitrary in the previous paper, expressions for different shapes of plants are derived. In continuation of the previous paper, the relation between the amount of nervous tissue and the form of an animal is discussed in more detail.  相似文献   

5.
The responsiveness to sex pheromone of males of Epiphyas postvittana was reduced by previous brief exposure to pheromone. Males were exposed to a standard quantity of pheromone for various durations and at various intervals before the time at which bioassay was performed.The reduction in responsiveness was related both to the duration of the previous exposure and to the time at which the previous exposure was given in relation to the bioassay. It was not related to the occurrence or intensity of any behavioural response elicited at the time of previous exposure to the pheromone.  相似文献   

6.
The time interval since previous anaesthesia was compared in a surgical population in South Wales and in patients who developed jaundice after halothane. There was a significant difference in the pattern of time interval since previous general anaesthetics in the surgical population and in those patients who developed jaundice after halothane. In the group who developed jaundice there was an “excess” of patients who had had a previous halothane anaesthetic within four weeks. Halothane should if possible be avoided in patients who have had it before, particularly if this was within the previous four weeks. In the case of repeat halothane anaesthetics within four weeks, the risk seems to lie between 1 in 6,000 and 1 in 22,000.  相似文献   

7.
It was hypothesized that (1) previous experience of aphids on a host plant leads to differences in their feeding behavior relative to aphids without previous experience on it and that (2) a change in the physiological state of the aphid modifies their experience-induced behavior. Using electronic recording, the feeding behavior of the aphid Sitobion fragariae (Walker) on wheat Triticum aestivum L. and oat Avena sativa L. was examined, comparing aphids with or without previous experience on a given host and with or without a period of starvation before assessing probing behavior. All comparisons were performed within a single aphid clone to minimize the effect of genetic variation. Feeding behavior on wheat was significantly affected by previous experience and starvation. The effect of previous experience interacted with the host plant where feeding behavior was tested. Aphids feeding on wheat following previous experience on wheat showed a longer time and a higher number of pathway activities and less time in waveform F (i.e., mechanical stylet work and penetration difficulties) than did aphids feeding on wheat after a previous experience on oat. No differences in the time from the beginning of the recording until the first salivation into the sieve elements were found. When aphids were subjected to a period of starvation, the time devoted to xylem ingestion increased compared with that of nonconstrained aphids. These results are discussed in terms of factors affecting foraging decisions.  相似文献   

8.
Questions: Do differences in previous land use cause long-lasting changes in soil chemistry? Is vegetation composition affected by the previous land use after 50 years of secondary succession? Is the effect of previous land use caused by pre-existing differences in environmental conditions or mediated through changes in soil chemistry? How important is the effect of previous land use in relation to other factors? Location: Doupovské Mountains, Czech Republic. Methods: A stratified random sampling design was used to collect 91 vegetation relevés with accompanying soil samples. The effects of previous land use (arable field, meadow, pasture) on soil pH, organic carbon (C), total nitrogen (N), C:N ratio and available phosphorus were tested by an analysis of covariance. A canonical correspondence analysis and variation partitioning procedure were used to reveal relationships among previous land use, environmental factors and species composition. Results: Organic C, total N and C:N ratio were significantly influenced by previous land use, while available phosphorus and soil pH were not. Previous land use explained a significant part of the variation in species composition and its effects only partly overlapped with the effects of soil chemistry and terrain attributes. However, the species composition of post-agricultural forests was mostly determined by environmental factors not modified by previous land use. Conclusions: Forest communities that originate on abandoned agricultural land are primarily determined by natural environmental conditions. Nevertheless, the type of previous land use also modifies the species assemblages of these forests and needs to be considered as an important determinant of their composition.  相似文献   

9.
The present study was designed to establish whether factors such as previous estrus synchronization, corpus luteum and embryo number at the time of pregnancy diagnosis, changes in body condition score, milk production, clinical disease (mastitis or lameness) and the inseminating bull affect pregnancy loss from 38 to 90 days of gestation. We derived data from 601 pregnant lactating dairy cows from a single herd. Pregnancy diagnosis was performed by ultrasonography between Day 38 and 44 following insemination. We also recorded corpus luteum and embryo number at this time. Pregnancy loss was defined as a negative pregnancy diagnosis on the second palpation per rectum undertaken between 90 and 96 days after insemination. Data were analyzed using multiple logistic regression methods. Cows that had an additional corpus luteum were eight times less likely to miscarry. The risk of pregnancy loss was 3.1 times higher in cows bearing twins. A one unit reduction in body condition score from previous partum to 30 days postpartum resulted in a 2.4-fold increase in pregnancy loss. We noted a higher incidence of pregnancy loss in cows inseminated using semen from one of the six bulls used. This particular bull led to a 3.4-fold increase in the rate of pregnancy loss. Logistic regression analysis showed no significant effects of previous estrus synchronization, milk production, clinical disease, body condition at previous partum or at pregnancy diagnosis, or body condition change between previous partum and pregnancy diagnosis. Our findings indicate a positive relationship between the presence of an additional corpus luteum and the maintenance of gestation. Risk factors for pregnancy loss were twin pregnancy, reduced body condition after previous parturition and the inseminating bull.  相似文献   

10.
The purpose of this study was to evaluate the degree of cytological radiation damage to peripheral blood lymphocytes induced by 153Sm-EDTMP applied for palliation of metastatic bone pain. Blood samples from 16 patients (46-82 years old), 10 without previous radiotherapy and 6 with previous radiotherapy, were collected before and one hour after the administration of a mean activity of 41.7+/-5.8 MBq/kg of 153Sm-EDTMP. Then the lymphocytes were cultured for cytokinesis block micronucleus (MN) assay. The number of MNper binucleated cells (BC) in patients without previous radiotherapy before the treatment was of 0.030 (+/- 0.016) and after one hour 0.035 (+/- 0.013), although we could find inter individual differences. The basal MN/BC of the patients with no previous radiotherapy was similar to the controls. The increment in the percentage of BC with MN was similar in patients with and without previous radiotherapy. The observed mean of MN/BC is equivalent to a dose range of 0.05 to 0.10 Gy of 153Sm-EDTMP in vitro. The relatively low frequency of lymphocyte with micronuclei after the exposure to 153Sm-EDTMP supported the contention that radiation damage in lymphocytes of patients with painful bone metastases is minimal.  相似文献   

11.
K Matsuno  J Lu 《Bio Systems》1991,25(4):213-218
The natural language processor in the brain generates information when it disambiguates words while reading a text in which information generation refers to making semantic commitments. Contextual facilitation of disambiguation of words appearing in the perturbed text that is derived from the unperturbed and natural one by deleting words randomly, lets the language processor revise the previous semantic commitments continuously. As the frequency of revising the previous semantic commitments increases, the amount of information generated by the language processor also increases. Revising previous semantic commitments in a continuous fashion is the functional property intrinsic to the language processor in the brain.  相似文献   

12.
Predator diet is known to influence antipredator behaviour in prey. Yet, it is not clear how antipredator behaviour is affected by diet changes of the predator. We studied the effect of previous and present diet of a predatory mite Typhlodromips swirskii on the antipredator response of its prey, the whitefly Bemisia tabaci. An earlier study showed that adult female whiteflies that had experienced predators, had learned to avoid ovipositing on plants with predators whose previous and present diet consisted of whitefly eggs and immatures. Here, we investigate whether adult whiteflies also avoid plants with predators whose present and/or previous diet consisted of a non-whitefly food source. Adult whiteflies were found not to avoid plants with predators whose present diet consisted of pollen and whose previous diet had consisted of either pollen or whitefly eggs and larvae. They did avoid plants with predators whose present diet consisted of whiteflies and whose previous diet had consisted of pollen, but to a lesser extent than when previous and present diet consisted of whiteflies. In a choice experiment, whiteflies discriminated between plants with predators whose present diet consisted of whiteflies, but that differed in previous diet. Our results show that both previous and present diets of predators are important in eliciting antipredator behaviour.  相似文献   

13.
In the present study determinative factors for ragweed (Ambrosia elatior) pollination were studied in Budapest between 1991 and 1996. The aim was to create a model to predict the day-to-day pollen count variation. The pollen concentration is determined mostly by the potential concentration and the mean concentration of the three previous days. These two variables can explain 56% of the total variance. Daily mean and maximum temperature, daily temperature fluctuation and the number of hours of sunshine in the previous day have a significant positive effect on the pollen count. The amount of precipitation on the previous day, relative humidity on the actual and on the previous day influence it negatively. When a cyclone prevails, pollen concentration is usually lower than the seasonal average. Some anticyclonal situations have a similar effect, while other anticyclonal types promote pollination. A predictive model was then created by multiple regression using the potential concentration, the mean concentration of the three previous days, the daily temperature fluctuation and the synoptic type as independent variables. This model can explain more than 68% of the total variance, and its accuracy is >71%. The model seems to predict accurately the trends during the pollen seasons, thus it will probably be a good tool in the practical prediction in Budapest, and the methodology will hopefully be applicable to other sites of the Carpathian Basin too.  相似文献   

14.
The hypothesis that growth in Pacific salmon Oncorhynchus spp. is dependent on previous growth was tested using annual scale growth measurements of wild Chinook salmon Oncorhynchus tshawytscha returning to the Yukon and Kuskokwim Rivers, Alaska, from 1964 to 2004. First-year marine growth in individual O. tshawytscha was significantly correlated with growth in fresh water. Furthermore, growth during each of 3 or 4 years at sea was related to growth during the previous year. The magnitude of the growth response to the previous year's growth was greater when mean year-class growth during the previous year was relatively low. Length (eye to tail fork, L ETF) of adult O. tshawytscha was correlated with cumulative scale growth after the first year at sea. Adult L ETF was also weakly correlated with scale growth that occurred during freshwater residence 4 to 5 years earlier, indicating the importance of growth in fresh water. Positive growth response to previous growth in O. tshawytscha was probably related to piscivorous diet and foraging benefits of large body size. Faster growth among O. tshawytscha year classes that initially grew slowly may reflect high mortality in slow growing fish and subsequent compensatory growth in survivors. Oncorhynchus tshawytscha in this study exhibited complex growth patterns showing a positive relationship with previous growth and a possible compensatory response to environmental factors affecting growth of the age class.  相似文献   

15.
The composition of weed species in spring barley and weed biodiversity was evaluated in experiments in different growing seasons and with different previous crops. The aim of the experiments was to evaluate the composition of weed species in spring barley during a four year period in weather conditions of different growing seasons and with different previous crop as well as to assess the biodiversity in the experiments where the different groups of herbicides were applied. Over years and previous crops, the dicotyledonous weed community was dominated by Chenopodium album, followed by Viola arvensis. The herbicides from different groups had significant influences on the biodiversity of weeds.  相似文献   

16.
MOTIVATION: Expressed sequence tag (EST) data reflects variation in gene expression, but previous methods for finding coexpressed genes in EST data are subject to bias and vastly overstate the statistical significance of putatively coexpressed genes. RESULTS: We introduce a new method (LNP) that reports reasonable p-values and also detects more biological relationships in human dbEST than do previous methods. In simulations with human dbEST library sizes, previous methods report p-values as low as 10(-30) on 1/1000 uncorrelated pairs, while LNP reports significance correctly. We validate the analysis on real human genes by comparing coexpressed pairs to gene ontology annotations and find that LNP is more sensitive than the three previous methods. We also find a small but statistically significant level of coexpression between interacting proteins relative to randomized controls. The LNP method is based on a log-normal prior on the distribution of expression levels.  相似文献   

17.
The effects of feeding with a histidine-excess diet and subsequent starvation on liver and muscle glycogen, and on serum glucose were investigated in young and adult rats.

Feeding with a histidine-excess diet resulted in the accumulation of liver glycogen in both young and adult rats. The hepatic glycogen continued to decrease during starvation, and the liver became almost totally depleted of glycogen after starvation for 48 hr. Glycogen in the liver of young rats starved for 24 hr after previous feeding with a histidine-excess diet was significantly higher than that of young rats starved for 24 hr after previous feeding with a basal diet.

Muscle glycogen after feeding and subsequent starvation was not affected by the types of diets fed previously, muscle glycogen during starvation showing a slight decrease in young rats and a slight increase in adult rats.

Feeding with a histidine-excess diet caused a significant decrease of serum glucose in young rats, but not in adult rats. Serum glucose in young rats was markedly reduced by starvation after previous feeding with a basal diet, but not after previous feeding with a histidine-excess diet. In adult rats, there were no changes in serum glucose between rats starved after feeding with either a basal diet or a histidine-excess diet, and serum glucose was decreased slightly by starvation after feeding with the test diets.

The overall results indicate that the maintenance of serum glucose in young rate even during starvation after previous feeding with a histidine-excess diet might be partially concerned with the export of glucose from the accumulated glycogen in the liver due to the diet.  相似文献   

18.
Hydrogen exchange-rate probability density functions for lysozyme have been derived by numerical Laplace inversion with the computer program CONTIN. The resulting solution set includes a smooth bimodal solution in agreement with previous analytical results together with a smooth three-peak solution. Numerical analysis of lysozyme hydrogen-exchange data in glycerol/water cosolvent mixtures confirms the previous assignment of the slow-exchange peak to an exchange mechanism involving reversible unfolding. Physicochemical constrations that can reduce the size of the solution set are described. The results are compared with those obtained from previous analytical methods and the limitations of the discrete class and analytical appraches are discussed.  相似文献   

19.
A previous model for lipid-anesthetic interaction is modified to account for anesthetics which bind to the headgroup-interface region of the bilayer rather than the acyl chain region. The new models account for anesthetic-induced changes in membrane phase transition temperature and permeability as well as the previous model, while still accounting for pressure reversal of anesthesia. In addition, the new models account for a 'saturation' of the effect of increasing concentrations of anesthetic on the membrane phase transition temperature, in agreement with experiment and in contrast to our previous model.  相似文献   

20.
The study presented in this article was designed to complete a dosimetry protocol required to establish the RF exposure levels at 100 MHz for measurement of the effect on cognition in human volunteers near the resonant frequency in seated positions. The results are compared with those reported previously using the same experimental procedures, except with the vertically radiating dipole antenna and corner reflector raised by .30 m to the vertical center of the anechoic chamber. The average whole body SAR for the high and low SAR conditions used in the previous study was achieved with a 12% increase in transmitter forward power. However, the incident power density averaged over the body was increased by 42%, from 40 and 80 W/m(2) in the previous study to 57 and 113 W/m(2) in the current study to achieve the same whole body average SAR used in the previous study. The differences in field patterns and field intensities between the previous and current studies were introduced by interactions between the E-field and RF absorbers in the floor and ceiling, which represent resonant structures at 100 MHz.  相似文献   

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