首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
3.
Bioremediation of wastewaters represents an important treatment methodology, especially when examined against the backdrop of ever-stricter legislation that is evolving in order to regulate effluent release into the environment. It has been reported that bioremediation specifically holds promise in solving environmental problems. Crucial questions surrounding the treatment of effluents include: efficiency of the process, economic feasibility, legal requirements, and the mechanisms involved in the remediation process. Of all these issues mentioned, the last requires special attention. This paper investigates these matters and focuses on techniques that are currently employed to determine the efficiency of bioremediation and mechanisms involved therein. The physiological significance of biosorption is also examined, as this subject has not been fully addressed in previous publications.  相似文献   

4.
Twelve years'' experience in providing summer employment for students in official health agencies in British Columbia is reviewed and a two-week orientation course given prior to employment in 1964 is described. In the program, which provides experience in teaching, research and community service, a total of 43 students have been employed. Students seeking this type of employment and accepted for it tend to have high academic standing. They prefer employment in or near Vancouver irrespective of their original home location. Two main employers have been available: specialized agencies in metropolitan Vancouver, or “rural” health units. Students serving in health units showed a strong tendency to enter general practice after graduation. Urban experience tended to lead to specialization.  相似文献   

5.
6.
7.
Auditory verbal hallucinations have attracted a great deal of scientific interest, but despite the fact that they are fundamentally a social experience—in essence, a form of hallucinated communication—current theories remain firmly rooted in an individualistic account and have largely avoided engagement with social cognition. Nevertheless, there is mounting evidence for the role of social cognitive and social neurocognitive processes in auditory verbal hallucinations, and, consequently, it is proposed that problems with the internalisation of social models may be key to the experience.  相似文献   

8.
9.
Small RNA viruses such as influenza viruses extensively manipulate host-cell functions to support their replication. At the same time the infected cell induces an array of defence mechanisms to fight the invader. These processes are mediated by a variety of intracellular signalling cascades. Here we will review the current knowledge of functional kinase signalling and apoptotic events in influenza virus infected cells and how these viruses have learned to misuse these cellular responses for efficient replication.  相似文献   

10.
Adenomas and hamartomas, two genetically transmitted histologic types of gastrointestinal polyposis, are associated in syndromes with extragastrointestinal manifestations. Adenomas that predispose to adenocarcinoma are basic to familial polyposis coli, the Gardner syndrome and the Turcot syndrome. Gastrointestinal polyps and extragastrointestinal lesions serve as a warning, providing time for diagnosis and treatment of adenomas to prevent their malignant transformation in patients and their relatives. Hamartomas with no malignancy potential, but having a tendency toward bleeding and bowel obstruction, are associated with the Peutz-Jeghers syndrome, juvenile polyposis, multiple hamartoma syndrome, basal-cell nevus syndrome and the Cronkhite-Canada syndrome. Most of these lesions and syndromes follow the inheritance pattern of a single autosomal dominant gene.  相似文献   

11.
12.

Background

Bladder cancer is the fourth most common malignancy in men, with a recurrence rate of 33–64%. Tumor documentation during cystoscopy of the bladder is suboptimal and might play a role in these high recurrence rates.

Objective

In this project, a bladder registration and navigation system was developed to improve bladder tumor documentation and consequently increase reproducibility of the cystoscopy.

Materials/Methods

The bladder registration and navigation system consists of a stereo-tracker that tracks the location of a newly developed target, which is attached to the endoscope during cystoscopy. With this information the urology registration and navigation software is able to register the 3D position of a lesion of interest. Simultaneously, the endoscopic image is captured in order to combine it with this 3D position. To enable navigation, navigational cues are displayed on the monitor, which subsequently direct the cystoscopist to the previously registered lesion. To test the system, a rigid and a flexible bladder phantom was developed. The system''s robustness was tested by measuring the accuracy of registering and navigating the lesions. Different calibration procedures were compared. It was also tested whether system accuracy is limited by using a previously saved calibration, to avoid surgical delay due to calibration. Urological application was tested by comparing a rotational camera (fixed to the rotating endoscope) to a non-rotational camera (dangling by gravity) used in standard urologic practice. Finally, the influence of volume differences on registering and navigating was tested.

Results/Conclusion

The bladder registration and navigation system has an acceptable accuracy for bladder lesion registration and navigation. Limitations for patient determinants included changes in bladder volume and bladder deformation. In vivo studies are required to measure the effect of these limitations and functionality in urological practice as a tool to increase reproducibility of the cystoscopy.  相似文献   

13.
The 1998–2000 war between Ethiopia and Eritreapitted former allies against each other, endingnew opportunities for development anddemocracy. We examine discursive constructionof the war, including Western media coverageand propaganda from both governments, but focuson discourse of exiled Ethiopians committed topolitical struggles in their former homeland,using the concept of long-distance nationalism.To investigate one form of long-distancenationalism, resurgent Abyssinianfundamentalism, we turn to sites of itsdiscursive production, including the magazine,Ethiopian Review, and the Internet. Theorists of transnationalism have consideredthe Internet as a site for new forms ofcommunication and community and argue thatInternet discourse among diaspora professionalsand academics embodies a creolizeddiscourse produced by a distinctive type, thecybernaut. In the case of the Abyssiniancybernauts, however, we detect not a newcreolized discourse but a ghostly repetitionof old views.  相似文献   

14.
The theory of behavioral syndromes focuses on quantifying variation in behavior within and among individual organisms and attempts to account for the maintenance of differences in behavior that occur in a consistent manner among individuals. Behavioral syndromes have potentially important ecological consequences (e.g. survivorship tradeoffs) and can be shaped by population dynamics through selective mortality. Here, we search for any evidence for consistency of behavior across situations in juveniles of a common damselfish, Pomacentrus amboinensis (Pomacentridae) at the transition between larval habitats in the plankton and juvenile habitats on the reef. Naïve fish leaving the pelagic phase to settle on reefs were caught by light traps and their behaviors observed using similar methods across three different situations (small aquaria, large aquaria, field setting); all of which represent low risk and well-sheltered environments. Seven behavioral traits were compared within and among individuals across situations to determine if consistent behavioral syndromes existed. No consistency was found in any single or combination of behavioral traits for individuals across all situations. We suggest that high behavioral flexibility is likely beneficial for newly-settled fish at this ontogenetic transition and it is possible that consistent behavioral syndromes are unlikely to emerge in juveniles until environmental experience is gained or certain combinations of behaviors are favored by selective mortality.  相似文献   

15.
Increased muscle activation during whole-body vibration (WBV) is mainly ascribed to a complex spinal and supraspinal neurophysiological mechanism termed the tonic vibration reflex (TVR). However, TVR has not been experimentally demonstrated during low-frequency WBV, therefore this investigation aimed to determine the expression of TVR during WBV.  Whilst seated, eight healthy males were exposed to either vertical WBV applied to the leg via the plantar-surface of the foot, or Achilles tendon vibration (ATV) at 25Hz and 50Hzfor 70s. Ankle plantar-flexion force, tri-axial accelerations at the shank and vibration source, and surface EMG activity of m. soleus (SOL) and m. tibialis anterior (TA) were recorded from the unloaded and passively loaded leg to simulate body mass supported during standing.  Plantar flexion force was similarly augmented by WBV and ATV and increased over time in a load- and frequency dependent fashion. SOL and TA EMG amplitudes increased over time in all conditions independently of vibration mode. 50Hz WBV and ATV resulted in greater muscle activation than 25Hz in SOL when the shank was loaded and in TA when the shank was unloaded despite the greater transmission of vertical acceleration from source to shank with 25Hz and WBV, especially during loading. Low-amplitude WBV of the unloaded and passively loaded leg produced slow tonic muscle contraction and plantar-flexion force increase of similar magnitudes to those induced by Achilles tendon vibration at the same frequencies. This study provides the first experimental evidence supporting the TVR as a plausible mechanism underlying the neuromuscular response to whole-body vibration.  相似文献   

16.
Coxsackievirus A16 (CVA16) is responsible for nearly 50% of all the confirmed hand, foot, and mouth disease (HFMD) cases in mainland China, sometimes it could also cause severe complications, and even death. To clarify the genetic characteristics and the epidemic patterns of CVA16 in mainland China, comprehensive bioinfomatics analyses were performed by using 35 CVA16 whole genome sequences from 1998 to 2011, 593 complete CVA16 VP1 sequences from 1981 to 2011, and prototype strains of human enterovirus species A (EV-A). Analysis on complete VP1 sequences revealed that subgenotypes B1a and B1b were prevalent strains and have been co-circulating in many Asian countries since 2000, especially in mainland China for at least 13 years. While the prevalence of subgenotype B1c (totally 20 strains) was much limited, only found in Malaysia from 2005 to 2007 and in France in 2010. Genotype B2 only caused epidemic in Japan and Malaysia from 1981 to 2000. Both subgenotypes B1a and B1b were potential recombinant viruses containing sequences from other EV-A donors in the 5’-untranslated region and P2, P3 non-structural protein encoding regions.  相似文献   

17.
Objective: To test women's ability to recall their past binging and purging behaviors. Design: Ten-year follow-up study of women who had participated in a cross-sectional survey during college. Subjects: In 1982, a sample of freshman and senior women at a large university in the Boston area were questioned about their weight, dieting history, bulimic symptoms, and eating patterns, attitudes, and concerns. In 1992, all subjects who responded to the 1982 survey were followed up to assess changes in bulimic symptoms and ability to recall past behaviors. Results: Among the 476 women who responded to both surveys, the percentage in 1992 who reported having ever binged and/or purged was less than the percentage in 1982, indicating that the recall of past behaviors was less than perfect. Denial in 1992 of ever having engaged in the behaviors ranged from 22% among the women who were self-inducing vomiting in 1982 to 64% among the women who had reported current fasting or strict dieting in 1982. Recall of past behaviors in 1992 was better among the women who had been current bingers or purgers in 1982. Conclusion: Our results demonstrate that ability to recall past binging and purging is only modest. Therefore to better understand the mental and physical health consequences of these behaviors this information should be collected prospectively.  相似文献   

18.

Background

Globally there are only less long-term-studies on hypertension available to provide reliable estimates and identify risk groups. This study aims to analyse the prevalence and long-term-trend of hypertension in Austria, recognize affected subpopulations and investigate social inequalities.

Methods

This representative population-based study is based on self-reported data of adults (mean age: 47.7 ± 17.5; n = 178,818) that were taken from five health surveys between 1973 and 2007. An adjustment of self-reported BMI was performed based on a preliminary validation study. Absolute changes (AC) and aetiologic fractions (AF) were calculated from logistic regressions in order to measure trends. To quantify the extent of social inequality, a relative index of inequality (RII) was computed.

Results

During the study period the age-standardized hypertension prevalence increased from 1.0% to 18.8%, with a considerable rise from 1991 onwards. There was a positive trend in all subpopulations, with the highest AC among obese women (+50.2%) and obese subjects aged 75 years and older (+54.4%), whereas the highest risk was observed among the youngest obese adults (AF: 99.4%). The RII for hypertension was higher for women than men, but in general unstable during the investigation period.

Conclusions

Obesity and older age are significant factors for increased morbidity of hypertension. The most undesirable trends occurred in obese women and obese subjects aged 75 years and older. These risk groups should be given special attention when planning hypertension prevention programs. The high increase in the prevalence of hypertension is due to different aspects, e.g. a demographic change and a change in the definition of hypertension. These findings help to understand why hypertension is becoming more common in the Austrian population.  相似文献   

19.
Point mutations in the human prion protein gene, leading to amino acid substitutions in the human prion protein contribute to conversion of PrPC to PrPSc and amyloid formation, resulting in prion diseases such as familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease (GSS), and fatal familial insomnia. We have investigated impressions of prevalent mutations including Q217R, D202N, F198S, on the human prion protein and compared the mutant models with wild types. Structural analyses of models were performed with molecular modeling and molecular dynamics simulation methods. According to our results, frequently occurred mutations are observed in conserved and fully conserved sequences of human prion protein and the most fluctuation values occur in the Helix 1 around residues 144-152 and C-terminal end of the Helix 2. Our analysis of results obtained from MD simulation clearly shows that this long-range effect plays an important role in the conformational fluctuations in mutant structures of human prion protein. Results obtained from molecular modeling such as creation or elimination of some hydrogen bonds, increase or decrease of the accessible surface area and molecular surface, loss or accumulation of negative or positive charges on specific positions, and altering the polarity and pKa values, show that amino acid point mutations, though not urgently change the stability of PrP, might have some local impacts on the protein interactions which are required for oligomerization into fibrillar species.  相似文献   

20.
Abstract

Point mutations in the human prion protein gene, leading to amino acid substitutions in the human prion protein contribute to conversion of PrPC to PrPSc and amyloid formation, resulting in prion diseases such as familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease (GSS), and fatal familial insomnia. We have investigated impressions of prevalent mutations including Q217R, D202N, F198S, on the human prion protein and compared the mutant models with wild types. Structural analyses of models were performed with molecular modeling and molecular dynamics simulation methods. According to our results, frequently occurred mutations are observed in conserved and fully conserved sequences of human prion protein and the most fluctuation values occur in the Helix 1 around residues 144–152 and C-terminal end of the Helix 2. Our analysis of results obtained from MD simulation clearly shows that this long-range effect plays an important role in the conformational fluctuations in mutant structures of human prion protein. Results obtained from molecular modeling such as creation or elimination of some hydrogen bonds, increase or decrease of the accessible surface area and molecular surface, loss or accumulation of negative or positive charges on specific positions, and altering the polarity and pKa values, show that amino acid point mutations, though not urgently change the stability of PrP, might have some local impacts on the protein interactions which are required for oligomerization into fibrillar species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号