酸沉降对森林生态系统影响的研究现状及展望

酸沉降影响下物质循环及其不平衡研究;酸沉降对土壤理化性质的影响;森林水化学方面的研究;酸沉降下重金属的活化研究;酸沉降对植物生长的影响研究;酸沉降和气候变化对森林的影响;模拟酸雨对土壤理化性质和植物生长的影响;酸沉降下土壤风化问题的研究;运用模型对酸化问题的研究;森林土壤人为和自然的酸化;酸沉降临界负荷的研究;酸沉降和其它污染物对植物的联合影响;酸化土壤恢复研究等方面介绍了酸沉降对森林生态系统影响的研究现状,并阐明了今后研究的方向及应该注意的问题。     

A comparative study of integrated pest management strategies based on impulsive control

The paper presents a comprehensive numerical study of mathematical models used to describe complex biological systems in the framework of integrated pest management. Our study considers two specific ecosystems that describe the application of control mechanisms based on pesticides and natural enemies, implemented in an impulsive and periodic manner, due to which the considered models belong to the class of impulsive differential equations. The present work proposes a numerical approach to study such type of models in detail, via the application of path-following (continuation) techniques for nonsmooth dynamical systems, via the novel continuation platform COCO (Dankowicz and Schilder). In this way, a detailed study focusing on the influence of selected system parameters on the effectiveness of the pest control scheme is carried out for both ecological scenarios. Furthermore, a comparative study is presented, with special emphasis on the mechanisms upon which a pest outbreak can occur in the considered ecosystems. Our study reveals that such outbreaks are determined by the presence of a branching point found during the continuation analysis. The numerical investigation concludes with an in-depth study of the state-dependent pesticide mortality considered in one of the ecological scenarios.     

An In Vivo Study of Self-Regulated Study Sequencing in Introductory Psychology Courses

Study sequence can have a profound influence on learning. In this study we investigated how students decide to sequence their study in a naturalistic context and whether their choices result in improved learning. In the study reported here, 2061 undergraduate students enrolled in an Introductory Psychology course completed an online homework tutorial on measures of central tendency, a topic relevant to an exam that counted towards their grades. One group of students was enabled to choose their own study sequence during the tutorial (Self-Regulated group), while the other group of students studied the same materials in sequences chosen by other students (Yoked group). Students who chose their sequence of study showed a clear tendency to block their study by concept, and this tendency was positively associated with subsequent exam performance. In the Yoked group, study sequence had no effect on exam performance. These results suggest that despite findings that blocked study is maladaptive when assigned by an experimenter, it may actually be adaptive when chosen by the learner in a naturalistic context.     

To What did They Consent? Understanding Consent Among Low Literacy Participants in a Microbicide Feasibility Study in Mazabuka,Zambia

We conducted a study to review the consenting process in a vaginal Microbicide feasibility study conducted in Mazabuka, Zambia. Participants were drawn from those participating in the microbicide study. A questionnaire and focus group discussion were used to collect information on participants understanding of study aims, risks and benefits. Altogether, 200 participants took part in this study. The results of the study showed that while all participants signed or endorsed their thumbprints to the consent forms, full informed consent was not attained from most of the participants since 77% (n = 154) of the participants had numerous questions about the study and 34% (n = 68) did not know who to get in touch with concerning the study. Study objectives were not fully understood by over 61% of the participants. Sixty four percent of the participants were not sure of the risks of taking part in the microbicide study. A significant number thought the study was all about determining their HIV status. Some participants were concerned that their partners were not on the trial as they were convinced that being on the study meant that that they had a lifetime protection from HIV infection. The process of obtaining consent was inadequate as various phases of the study were not fully understood. We recommend the need for researchers to reinforce the consenting process in all studies and more so when studies are conducted in low literacy populations.     

The Measurement of Sexual Selection Using Bateman's Principles: An Experimental Test in the Sex-Role-Reversed Pipefish Syngnathus typhle

Angus J. Bateman's classic study of sexual selection in Drosophila melanogaster has had a major influence on the development of sexual selection theory. In some ways, Bateman's study has served a catalytic role by stimulating debate on sex roles, sexual conflict and other topics in sexual selection. However, there is still considerable disagreement regarding whether or not "Bateman's principles" are helpful in the study of sexual selection. Here, we test the idea that Bateman's principles provide the basis for a useful method to quantify and compare mating systems. In this study, we focus on the sex-role-reversed pipefish Syngnathus typhle as a model system to study the measurement of sexual selection. We set up artificial breeding assemblages of pipefish in the laboratory and used microsatellite markers to resolve parentage. Three different sex-ratio treatments (female-biased, even and male-biased) were used to manipulate the expected intensity of sexual selection. Measures of the mating system based on Bateman's principles were calculated and compared to the expected changes in the intensity of sexual selection. We also compare the results of this study to the results of a similar study of Bateman's principles in the rough-skinned newt, a species with conventional sex roles. The results of this experiment show that measures of the mating system based on Bateman's principles do accurately capture the relative intensities of sexual selection in the different treatments and species. Thus, widespread use of Bateman's principles to quantify mating systems in nature would facilitate comparative studies of sexual selection and mating system evolution.     

Molecular mechanical study of the stability of the Lys-Ala-Ala tripeptide dimer.

A molecular mechanical study of two Lys-Ala-Ala tripeptide chains in interaction is presented. The study was carried out to explore the feasibility of dimer formation and explain some features of the crystal structure not completely understood. The role of the counterions present in the crystal structure on the conformation has been included in this study by investigating the effect of removing the charges on the lysyl side chains. The results of the present molecular mechanical study explains well the structural features found by X-ray crystallography, complementing that study.     

Assessment of feto-placental well-being in the mare from mid-gestation to term: transrectal and transabdominal ultrasonographic features

Ultrasound assessment of feto-placental well-being has found its application in the equine field, as a valid diagnostic tool. Most reports on equine fetal parameters focus on advanced to late gestation. The aim of the present study was to further validate the technique of ultrasound evaluation of the equine fetal environment, by extending its application to earlier stages of pregnancy. Fetal parameters were collected (on 150 pregnancies) over a 3-year period. Data included in the study were selected according to the clinical behaviour of the mare, the neonate/fetus and fetal membranes at the termination of gestation. Validation of the ultrasound technique was also undertaken on a number of specimens collected at an abbatoir. At the completion of the study, a substantial number of measurements and observations were collected. No fetal parameters associated in previous reports with a negative outcome were observed at any of the examinations during this study. Therefore, data collected during the present study should be of value in feto-placental assessment of well-being, in mid- to late-gestation.     

Effects of a 21 day metabolic study on serum opsonic activity in female college students, assessed by a chemiluminescence technique.

A metabolic study to evaluate nutritional balance, in which subjects have to eat all the foods supplied and maintain a set schedule, is thought to be stressful for the subjects. The effects of stress on the immune system have been studied extensively. However, there are no studies of non-specific immunological changes during a metabolic study. Serum opsonic activity (SOA) is a direct and suitable indicator of non-specific humoral immunity. In this study, we used luminol-dependent chemiluminescence (LmCL) to measure reactive oxygen species (ROS) generation from pooled human neutrophils as an indicator of SOA. We also measured serum immunoglobulin levels and plasma myeloperoxidase (MPO) activity. Eleven female college students took part in this 21 day metabolic study after giving their written informed consent. The results obtained suggest that the metabolic study has almost no effect on immunoglobulin levels. According to MPO levels, neutrophils in vivo may be deactivated to some minor extent. In contrast to these results, peak time (PT) and peak height (PH) of LmCL were changed significantly during the metabolic study. In conclusion, SOA increased during the 21 day metabolic study. There was no significant correlation between SOA and serum immunoglobulin levels on any of the study days.     

Sources and Patterns of Wolverine Mortality in Western Montana

ABSTRACT We instrumented 36 wolverines (Gulo gulo) on 2 study areas in western Montana and one study area on the Idaho-Montana (USA) border: 14 (9 M, 5 F) on the Pioneer study area, 19 (11 M, 8 F) on the Glacier study area, and 3 (2 M, 1 F) on the Clearwater study area. During 2002–2005, harvest from licensed trapping accounted for 9 (6 M, 3 F) of 14 mortalities, including individuals from all 3 study areas. Based on Akaike's Information Criterion adjusted for small sample sizes (AIC_c) rankings of 8 a priori models, a trapping model and a trapping-by-sex interaction model were equally supported (ΔAIC_c < 2) in explaining wolverine survival. Estimated annual survival was 0.80 when we did not consider harvest, whereas additive mortality from harvest reduced annual survival to 0.57. Glacier National Park in the Glacier study area provided some refuge as evidenced by an annual survival rate of 0.77 compared to 0.51 for the Pioneer Mountain study area. We incorporated these survival rates into a simple Lefkovitch stage-based model to examine rates of population change. The finite rate of population change (Λ) for the Glacier study area was 1.1, indicating a stable to slightly increasing population, whereas Λ for the Pioneer study area was 0.7, indicating a 30% annual population decrease during our study. Changes in Λ for both study areas were most sensitive to adult survival. In 2004, we used a Lincoln Index to estimate that 12.8 ± 2.9 (95% CI) wolverines resided in the 4 mountain ranges comprising the Pioneer study area, suggesting that small, island ranges in western Montana supported few individuals. Our results suggest that if wolverines are harvested, they should be managed within individual mountain ranges or small groupings of mountain ranges to limit mortality to within biologically defined limits in recognition of the increased vulnerabilities owing to low fecundity and low population numbers in small mountain ranges. We found that refugia, such as Glacier National Park, were important by reducing trap mortality and providing immigrants to the surrounding population, but even large parks were inadequate to provide complete protection to wolverines from trapping as they ranged outside park borders.     

Effects of dietary protein and butylated hydroxytoluene on the kidneys of rats

Semipurified diet using Na-caseinate or lactalbumin as the only protein source was given to female rats to study the influence of nephrocalcinosis on butylated hydroxytoluene (BHT) induced kidney damage. The study showed, that BHT induces nephropathy in female rats irrespective of the diet used. Pronounced nephrocalcinosis was only found in rats fed the Na-caseinate diet. Thus, this study does not indicate a connection between the development of the BHT-nephropathy and nephrocalcinosis. The results from this study once more stress the influence of the diet on reaction of the animal to experimental procedures.     

Nest predation in hole-nesting birds in relation to habitat edge: an experiment

We experimentally tested the hypothesis that nest predation rate in hole-nesting birds, especially the common goldeneye Bucephala clangula , was related to the edge between aquatic and terrestrial habitats We also studied whether nest predation rate was related to habitat patch (lake) size In three study areas nest-boxes were erected in pairs one nest-box was erected at the shoreline and the other one inside the forest at a varying distance (range from 14 to 140 m) from the shoreline One chicken egg was placed in each nest-box (dummy nest) Overall predation rate on dummy nests varied from 34 6% to 52 6% depending on the study area The pine marten Martes manes was the primary nest predator m all study areas Daily predation rates did not differ between natural and dummy nests Predation rate on dummy nests was not related to the distance of the nest-box from the shoreline in any study area Predation rate was not related to lake size in two study areas but in one area predation rate on dummy nests was lower around largest lakes However, the result may be accidental and not because of lake size per se because the proportion of forest was exceptionally low in that part of the study area     

Summary of a Canadian Study of Smoking and Health

The object of this study was to investigate the relationship between residence, occupation and smoking habits, and mortality from chronic diseases, particularly lung cancer. It was a prospective study, initiated by a questionnaire sent to Canadian veteran pension recipients. The study was based on the replies of 78,000 males and 14,000 females, together with data on the deaths occurring among these respondents over a six-year follow-up period—July 1, 1956 to January 30, 1962.The outstanding finding of this study was that cigarette smokers compared to non-smokers had excessive mortality, particularly from heart and circulatory diseases, lung cancer, and bronchitis and emphysema. The mortality ratios for heart and circulatory diseases were elevated even for those who smoked cigarettes less than five years, and remained relatively constant as the duration of smoking increased. The mortality ratios for lung cancer increased markedly as the duration of smoking increased. A small excess in mortality was noted among urban residents. An association between cause of death and occupation was not evident in this study.Findings based on the data on smoking collected in this study were incorporated into the Report of the U.S. Surgeon-General''s Advisory Committee on Smoking and Health.     

Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether

The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.     

Thermal expansion of blood vessels in low cryogenic temperatures, Part II: Vitrification with VS55, DP6, and 7.05 M DMSO

As part of the ongoing effort to study the mechanical behavior of biological materials in cryopreservation processes, the current study focuses on thermal expansion during vitrification (vitreous in Latin means glassy). A new device is utilized in this study, which has been described in detail in the companion paper (Part I). The current study (Part II) focuses on measurements of vitrified blood vessels permeated with the cryoprotectants VS55, DP6, and DMSO. Data analysis in this study includes polynomial approximation of experimental results in the lower part of the cryogenic temperature range, where the material behaves as solid over a practical time scale. The study further includes a unified thermal expansion analysis throughout the entire cryogenic temperature range by compiling the current results with previously reported data. Finally, analysis of the glass transition temperature, based on thermal strain data is presented.     

睡眠研究中相关动物选择的进展

在睡眠研究使用的各种实验动物中,除了常用的啮齿类动物,还有猫、果蝇、猴和斑马鱼等.啮齿类动物因制作其睡眠相关的模型简便易行而得到广泛的应用,主要是采用各种物理化学方法制作失眠动物模型;转基因小鼠主要应用于药物干预睡眠及睡眠发生机制的研究;果蝇和斑马鱼多用于遗传学中睡眠的研究;猫用于睡眠研究的历史悠久,多用于体内试验,对内源性神经递质进行定量分析;猴睡眠结构与人相似,被广泛用于神经生物学,行为药理学等领域与睡眠的关系研究中.由于各种实验动物特殊的生理特征,在睡眠研究中多根据研究目的选择不同的实验动物.     

Accelerated laboratory test to study fungal biodeterioration of cementitious matrix

The present study aimed to develop an accelerated laboratory test to study the biodeteriorative effect of different fungal strains to a cementitious matrix. The test developed in this study permits to obtain a rapid fungal development on cement specimens. Three months of experiments only are needed to obtain first results, which is rather shorter than other test developed to date to study fungal biodeterioration. Results are mainly related to aesthetical biodeterioration. Results show that in these experimental conditions, fungal growth occurs since the first week of incubation. Stereomicroscopy observations showed that microbial growth was noticed only on the surface of specimens, while PAS staining revealed the real extent of microbial growth on and within the matrix as later confirmed by SEM observations of cross section showing the penetration of hyphae inside the matrix. Test can be used with short time of incubation, to test and to compare bioreceptivity of cement-based materials; and several months of incubation should allow the study of mechanisms involved in biodeterioration.     

Effects of electromagnetic field emitted by cellular phones on the EEG during an auditory memory task: a double blind replication study

The effects of electromagnetic fields (EMF) emitted by cellular phones on the event related desynchronization/synchronization (ERD/ERS) of the 4-6, 6-8, 8-10, and 10-12 Hz electroencephalogram (EEG) frequency bands were studied in 24 normal subjects performing an auditory memory task. This study was a systematic replication of our previous work. In the present double blind study, all subjects performed the memory task both with and without exposure to a digital 902 MHz field in a counterbalanced order. We were not able to replicate the findings from our earlier study. All eight of the significant changes in our earlier study were not significant in the present double blind replication. Also, the effect of EMF on the number of incorrect answers in the memory task was inconsistent. We previously reported no significant effect of EMF exposure on the number of incorrect answers in the memory task, but a significant increase in errors was observed in the present study. We conclude that EMF effects on the EEG and on the performance on memory tasks may be variable and not easily replicable for unknown reasons.     

Is it a good idea to train fillies and colts separately?

This study compared the physiological response to novel situations in sex-separated and sex-mixed groups of horses, as measured by heart rate (HR). The study evaluated the possibility of training horses in a mixed-sex system. The study included 41 Purebred Arabian 2?-year-olds during their first walk on an automated horse walker. Four groups, divided by manner of care and training, consisted of 10 colts and 10 fillies kept in separate stables and trained in separate male or female groups and 12 colts and 9 fillies kept in the same stable and trained together. The study measured HR when horses were at rest before exercise, while moving from stable to walker, during 30 min of exercise on walker, while moving from walker to stable, and at rest after exercise. Mean HR scores recorded from training on the walker were higher in sex-mixed groups. Results obtained while horses were moving from stable to walker, then from walker to stable, were significantly higher in the sex-mixed groups. The study did not recommend training young horses in sex-mixed groups.     

Evaluation of endothelial permeability in brain tumors by dynamic magnetic resonance tomography with magnevist contrast imaging on low-field MR-tomograph

In order to study the endothelial permeability to hydrophilic macromolecules in brain tumors we have developed a technique based on Gjedde-Rutland-Patlak approach to dynamic MRI study with Gd-DTPA injected intravenously, performed with low-field MRI tomograph Magnetom Open (Siemens medical). 27 patients with various brain tumors were referred for the study. The indices of Gd-DTPA transport to tumor tissue (KGd-DTPA) vary substantially, depending on the degree of malignancy and deliver essential information on microvascular permeability of tumor capillary bed.