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 46 毫秒
1.
Book Reviews     
Book reviewed in this article: Ildiko Beller‐Hann and Chris Hann . Turkish Region: State, Market and Social Identities on the East Black Sea Coast. Santa Fe Lewis Roberts Binford . Constructing Frames of Reference: An Analytical Method for Archaeological Theory Building Using Ethnographic and Environmental Data Sets. Anne Chambers and Keith Stanley Chambers . Unity of Heart: Culture and Change in a Polynesian Atoll Society. Marcus Colchester and Christian Erni (eds) . Indigenous Peoples and Protected Areas in South and Southeast Asia. Michelle Ruth Gamburd . The Kitchen Spoon's Handle: Transnationalism and Sri Lanka's Migrant Housemaids. David N. Gellner and Eric Hirsch (eds.) . Inside Organizations: Anthropologists at Work. Geoffrey Gray (ed.). Jane C. Goodale, Ruth Fink, Jeremy Beckett, L. R. Hiatt, and J. A. Barnes . Before It's Too Late: Anthropological Reflections, 1950–1970. John N. Gray . At Home in the Hills: Sense of Place in the Scottish Borders. Kees Grijns and Peter J. M. Nas (eds) . Jakarta‐Batavia: Socio‐cultural Essays. Stephen Gudeman . The Anthropology of the Economy: Community, Market, Culture. Sarah Lamb . White Saris and Sweet Mangoes: Aging, Gender and Body in North India. Michael O'Hanlon and Robert Welsch (eds) . Hunting the Gatherers: Ethnographic Collectors, Agents and Agency in Melanesia, 1870s–1930s. Sherry B. Ortner . Life and Death on Mt. Everest: Sherpas and Himalayan Mountaineering. Judy and Tashi Tenzing . Tenzing and the Sherpas of Everest. Adrian Peace . A World of Fine Difference: The Social Architecture of a Modern Irish Village. George W. Stocking, Jr . Delimiting Anthropology: Occasional Inquiries and Reflections. Colin Tatz . Aboriginal Suicide Is Different: A Portrait Of Life and Self‐Destruction. Roger Tol, Kees van Dijk, and Greg Acciaioli (eds) . Authority and Enterprise among the Peoples of South Sulawesi Penny Van Esterik . Materializing Thailand.  相似文献   

2.

Shift work is indispensable in our modern society; therefore, measures for maintaining the health of shift workers are urgently required. In this prospective study observing the effects of different types of scheduled light–dark shift conditions in wild-type mice, we reared mice for 630 days under two chronic jet lag conditions with distinct programs of light and darkness: an 8-h phase delay every 7 days (delay, n = 14) or an 8-h phase advance every 4 days (advance, n = 34). “Delay” represents a mild condition in which mice are entrained, whereas “Advance” represents a condition of circadian rhythm disorder in which mice are not entrained. Our results showed that the 26.5% (9/34) mice reared under the “Advance” shift condition died or were sacrificed by humane endpoint throughout the experiment, whereas the first death under “Delay” condition occurred on day 611. The mortality rate of the mice reared under “Advance” condition was higher than the mice under “Delay” condition [HR (95% CI) 4.26 (0.54–33.6)]. In “Advance” mice of shorter lifespan, which showed splenomegaly and increased myeloid cells in bone marrow, which indicates that chronic inflammation existed in those mice. Although this study is still preliminary, these findings suggest that prolonged severe circadian rhythm disorder may result in the induction of chronic inflammation and tend to result in a shorter lifespan. Further studies are needed to understand why and how circadian rhythm disorder increases the risk of various dysfunction of physiology and diseases.

  相似文献   

3.
Phylogeny of birch mice is estimated using sequences of ten nuclear genes and one mitochondrial gene. Based on the results of tree reconstructions and molecular dating, five major lineages are recognized: “tianschanica,” “concolor,” “caudata,” “betulina,” and “caucasica.” It is established that the three latter lineages constitute a clade and that the long‐tailed birch mouse Sicista caudata is the sister group of the “caucasica” lineage. The “tianschanica” lineage is placed as the sister branch to all other species, however, with insufficient support. The cytochrome b tree is generally concordant with the nuclear topology. The molecular clock results suggest that the radiation among the main lineages occurred in the Late Miocene–Early Pliocene (6.0–4.7 Mya). The correspondence between molecular dating and the fossil record is discussed. Based on nuclear data, a high level of divergence between cryptic species in the “tianschanica” lineage is confirmed. Mitochondrial and nuclear data suggest the existence of a potential cryptic species within Sicista strandi.  相似文献   

4.
In birds, many behavioral and physiological processes that occur during reproduction show daily rhythms in response to environmental temporal constraints. In this study, the individual daily organization of laying and its genetic determinant in Japanese quail (Coturnix coturnix japonica) were analyzed. For this purpose, the oviposition time of 102 randomly chosen females, maintained in long-day photoperiodic conditions (LD 14h:10h) for 1 mon was observed and extreme phenotypes selected. Laying is characterized by two parameters: oviposition interval and laying hour.

The birds showed a specific time of laying during 24 h. All eggs were laid in the afternoon between 6.5 and 14 h after lights on (HALO). Two laying profiles were determined: 20% of females with an oviposition interval greater than 24 h (24.7±0.2 h) (the “delayed” profile) laid progressively later each day until a pause day. The remaining 80% of the females laid at the same time each day, with few pause days and an oviposition interval close to 24 h (24.0±0.2 h) (the “stable” profile). Among the females, showing this last profile, an intra-individual stability and an inter-individual variability of laying hour was established. Two extreme laying phenotypes were then determined: the “early” phenotype (E) for females laying on average between 7.5 and 9.5 HALO and the “late” phenotype (L) for females laying between 12.5 and 14 HALO.

In order to study the genetic basis of the laying hour, three females of each extreme phenotype were selected and crossed with two different males. The E and L females produced 57 F1E and 42 F1L daughters, respectively. F1 females displayed both laying profiles. However, the proportion of females displaying a “delayed” profile was higher in the L line (50%) than in the E line (29.8%). For the “stable” daughters, artificial selection induced an advance in laying hour of 4.7% for the E line and a delay of 4.7% for the L line. Realized heritability was estimated at 0.5. Moreover, the laying hour of the daughters was correlated positively to that of the mothers (N=61;r=0.45). These results support the notion of heritability of oviposition time in Japanese quail.  相似文献   

5.
6.
Background: We examine the effect of eradicating Helicobacter in idiopathic parkinsonism (IP). Marked deterioration, where eradication‐therapy failed, prompted an interim report in the first 20 probands to reach de‐blinding. The null‐hypothesis, “eradication has no effect on principal outcome, mean stride length at free‐walking speed,” was rejected. We report on study completion in all 30 who had commenced post‐treatment assessments. Methods: This is a randomized, placebo‐controlled, parallel‐group efficacy study of eradicating biopsy‐proven (culture and/or organism on histopathology) Helicobacter pylori infection on the time course of facets of IP, in probands taking no, or stable long‐t½, anti‐parkinsonian medication. Persistent infection at de‐blinding (scheduled 1‐year post‐treatment) led to open active eradication‐treatment. Results: Stride length improved (73 (95% CI 14–131) mm/year, p = .01) in favor of “successful” blinded active over placebo, irrespective of anti‐parkinsonian medication, and despite worsening upper limb flexor rigidity (237 (57–416) Nm × 10?3/year, p = .01). This differential effect was echoed following open active, post‐placebo. Gait did not deteriorate in year 2 and 3 post‐eradication. Anti‐nuclear antibody was present in all four proven (two by molecular microbiology only) eradication failures. In the remainder, it marked poorer response during the year after eradication therapy, possibly indicating residual “low‐density” infection. We illustrate the importance of eradicating low‐density infection, detected only by molecular microbiology, in a proband not receiving anti‐parkinsonian medication. Stride length improved (424 (379–468) mm for 15 months post‐eradication, p = .001), correction of deficit continuing to 3.4 years. Flexor rigidity increased before hydrogen‐breath‐test positivity for small intestinal bacterial overgrowth (208 (28–388) Nm × 10?3, p = .02), increased further during (171 (67–274), p = .001) (15–31 months), and decreased (136 (6–267), p = .04) after restoration of negativity (32–41 months). Conclusion: Helicobacter is an arbiter of progression, independent of infection‐load.  相似文献   

7.
K C Chou 《Biopolymers》1987,26(2):285-295
By means of the quasi-continuity theory developed recently [Chou, K.-C. (1983) Biochem. J. 209 , 573–580; Chou, K.-C. (1984) Biochem. J. 221 , 27–31; Chou, K.-C. (1985) Biophys. J. 48 , 289–297], the low-frequency breathing motions of the β-barrels in the 12 domains of an IgG antibody molecule have been calculated. The results are in very good agreement with the observed low-frequency peaks in the Raman spectra. Based on this, the resonant couplings among the domains located at its different regions are discussed. It turns out that some very interesting functions of antibody molecules, such as the “chelate effect” and “trigger effect” whose dynamic principle has been so far unknown, can be clearly elucidated in terms of a fundamental natural law; i.e., it is through the channel of low-frequency resonance that the “signal” (or energy) in an antibody is transmitted from one location to the other, so as to be able to induce the relevant conformational change required for operating those important biological functions. The physical picture illustrated here once again provides us with a classic example that structure and function in nature are highly harmonized.  相似文献   

8.
Recent molecular phylogenies conflict with traditional scleractinian classification at ranks ranging from suborder to genus, challenging morphologists to discover new characters that better agree with molecular data. Such characters are essential for including fossils in analyses and tracing evolutionary patterns through geologic time. We examine the skeletal morphology of 36 species belonging to the traditional families Faviidae, Merulinidae, Pectiniidae, and Trachyphylliidae (3 Atlantic, 14 Indo‐Pacific, 2 cosmopolitan genera) at the macromorphological, micromorphological, and microstructural levels. Molecular analyses indicate that the families are not monophyletic groups, but consist of six family‐level clades, four of which are examined [clade XV = Diploastrea heliopora; clade XVI = Montastraea cavernosa; clade XVII (“Pacific faviids”) = Pacific faviids (part) + merulinids (part) + pectiniids (part) + M. annularis complex; clade XXI (“Atlantic faviids”) = Atlantic faviids (part) + Atlantic mussids]. Comparisons among molecular clades indicate that micromorphological and microstructural characters (singly and in combination) are clade diagnostic, but with two exceptions, macromorphologic characters are not. The septal teeth of “Atlantic faviids” are paddle‐shaped (strong secondary calcification axes) or blocky, whereas the septal teeth of “Pacific faviids” are spine‐shaped or multidirectional. Corallite walls in “Atlantic faviids” are usually septothecal, with occasional trabeculothecal elements; whereas corallite walls in “Pacific faviids” are usually trabeculothecal or parathecal or they contain abortive septa. Exceptions include subclades of “Pacific faviids” consisting of a) Caulastraea and Oulophyllia (strong secondary axes) and b) Cyphastrea (septothecal walls). Diploastrea has a diagnostic synapticulothecal wall and thick triangular teeth; Montastraea cavernosa is also distinct, possessing both “Pacific faviid” (abortive septa) and “Atlantic faviid” (paddle‐shaped teeth) attributes. The development of secondary axes is similar in traditional Atlantic faviids and mussids, supporting molecular results placing them in the same clade. Subclades of “Pacific faviids” reveal differences in wall structure and the arrangement and distinctiveness of centers of rapid accretion. J. Morphol. 272:66–88, 2011. © 2010 Wiley‐Liss, Inc.  相似文献   

9.
In some bacteria, cysteine is converted to cysteine sulfinic acid by cysteine dioxygenases (CDO) that are only ~15–30% identical in sequence to mammalian CDOs. Among bacterial proteins having this range of sequence similarity to mammalian CDO are some that conserve an active site Arg residue (“Arg‐type” enzymes) and some having a Gln substituted for this Arg (“Gln‐type” enzymes). Here, we describe a structure from each of these enzyme types by analyzing structures originally solved by structural genomics groups but not published: a Bacillus subtilis “Arg‐type” enzyme that has cysteine dioxygenase activity (BsCDO), and a Ralstonia eutropha “Gln‐type” CDO homolog of uncharacterized activity (ReCDOhom). The BsCDO active site is well conserved with mammalian CDO, and a cysteine complex captured in the active site confirms that the cysteine binding mode is also similar. The ReCDOhom structure reveals a new active site Arg residue that is hydrogen bonding to an iron‐bound diatomic molecule we have interpreted as dioxygen. Notably, the Arg position is not compatible with the mode of Cys binding seen in both rat CDO and BsCDO. As sequence alignments show that this newly discovered active site Arg is well conserved among “Gln‐type” CDO enzymes, we conclude that the “Gln‐type” CDO homologs are not authentic CDOs but will have substrate specificity more similar to 3‐mercaptopropionate dioxygenases.  相似文献   

10.
Length–weight relationships (LWRs) were determined for seven riverine fish species from the river Ganga, India. Specimens were collected on a bi‐monthly basis from April 2017 to December 2018 using gill nets (mesh size 22–34 mm), cast nets (mesh size 16 mm) and bag nets (mesh size 14–22 mm). Total length was measured to the nearest 0.1 cm using a digital caliper and weight was recorded to the nearest 0.01 g on an electronic balance. From estimated length–weight relationships, the values for parameter “a” ranged from 0.004 (Bregmaceros mcclellandi and Setipinna tenuifilis) to 0.014 (Brachirus pan). Likewise, the values for the parameter “b” of the equation ranged from 2.958 (Bagarius bagarius) to 3.124 (Bregmaceros mcclellandi) and r2 from 0.978 (Gonialosa manmina) to 0.996 (Brachirus pan).  相似文献   

11.
Objective: To test the hypothesis that low‐income African‐American preschool children would have a higher BMI if their mothers reported greater “restriction” and “control” in feeding and if mothers reported that children showed greater “food responsiveness” and “desire to drink.” In addition, to test whether higher maternal “pressure to eat” would be associated with lower child BMI. Research Methods and Procedures: A questionnaire was completed by 296 low‐income African‐American mothers of preschool children. It assessed three constructs on maternal feeding strategies (“restriction,” “pressure to eat,” and “control”) and two on child eating behaviors (“food responsiveness” and “desire to drink”). Children's BMI was measured, and mothers’ BMI was self‐reported. Results: The mean (standard deviation) BMI z‐score of the children was 0.34 (1.5), and 44% of the mothers were obese (BMI ≥30 kg/m2). Only maternal “pressure to eat” had a significant overall association with child BMI z‐score (r = ?0.16, p < 0.01). Both maternal “restriction” and “control” were positively associated with children's BMI z‐score in the case of obese mothers (r = 0.20, p = 0.03 and r = 0.24, p = 0.007, respectively), but this was not so in the case of non‐obese mothers (r = ?0.16, p = 0.05 and r = ?0.07, p = 0.39, respectively). Discussion: Among low‐income African Americans, the positive association between maternal restriction and control in feeding and their preschoolers’ BMI was limited to obese mothers. Relations between parent feeding strategies and child weight status in this population may differ on the basis of maternal weight status.  相似文献   

12.
Molecular and “adaptive” evolution, cladistic and phylogeny. Supplementations to a working hypothesis The methods of molecular biology and morpholo for the taxonomical assessment have given in several cases very different results. The following examples are discussed: Ailuropoda melanoleuca as an ursoid member of the Carnivora (Ursidae or Ailuropodidae?), Homo saiens and his position to the African apes (Pan and Gorilla) (Pongidae or Hominidae?), Theroipithecus gelada and its affinities to the baboons (Papionini or Theropithecini ?) and Oreopithecus bambolii from the late Miocene of Italy and its taxonomical position within the catarrhine primates. For the three extant species not only the “two level evolution” (molecular and morphological-adaptative evolution) is evident, but also the working hypothesis, that the “adaptative” evolution is more rapidly as the molecular evolution, as the author is suggesting since 1969. The results of molecular methods (immunoloy, amino acid sequences, electrophoresis, DNA-DNA hybridization) are more important for the phylogeny than for the taxonomy. For the cladistic method it is clear, that a cladogram is not a phylogenetic tree, as suggested Peter Ax (1984).  相似文献   

13.
In the preceding study (Feder et al., 1990), we report that paired apple and hawthorn infesting populations of Rhagoletis pomonella are genetically differentiated for six allozymes. Here, we show that patterns of intra- and inter-host allele frequency variation seen for these six loci across the eastern United States are consistent on a more fine grained spatial scale in western Michigan. Malic enzyme, Aconitase-2, Mannose phosphate isomerase, and Hydroxyacid dehydrogenase all displayed significant linear relationships with latitude among five “regional” hawthorn populations sampled along a north-south transect between the cities of Cadillac and Portage, Michigan. Clines were not as evident among “regional” apple populations in western Michigan, although allele frequencies for Malic enzyme100, Mannose phosphate isomerase100 and Aconitase-295 varied with latitude among six “local” apple populations within a 60 km2 area near the town of Grant. Significant allele frequency differences were observed between hawthorn and apple populations at all “regional” and “local” collecting sites analyzed in the study (a total of 20 different apple and hawthorn populations). As was the case in the geographic survey of the eastern United States, the magnitude and pattern of inter-host frequency differences at “regional” and “local” sites were a function of latitude. Host related genetic differentiation was consistent on a “microgeographic” scale as well. Allele frequencies for Malic enzyme100 and Aconitase-295 were significantly higher over a four-year period (1984 to 1987) for flies sampled from individual hawthorn trees (N = 6) than apple trees (N = 7) within an old field (0.09-km2 area) located near Grant. The fine level of genetic subdivision between hawthorn and apple populations of R. pomonella in western Michigan substantiates the existence of host associated polymorphism in the fly and supports a sympatric mode of divergence for the “apple race”.  相似文献   

14.
Modelling load bearing in diarthrodial joints is challenging, due to the complexity of the materials, the boundary and interface conditions and the geometry. The articulating surfaces are covered with cartilage layers that are filled with a fluid that plays a major role in load bearing [Mow, V.C., Holmes, M.H., Lai, W.M. (1984) “Survey article: fluid transport and mechanical properties of articular cartilage: a review”, Journal of Biomechanics 17(5), 377–394]. Researchers have tended to approximate joint geometry using axisymmetry [Donzelli, P.S., Spilker, R.L., Ateshian, G.A., Mow, V.C. (1999) “Contact analysis of biphasic transversely isotropic cartilage layers and correlations with tissue failure”, Journal of Biomechanics 32, 1037–1047], often with a rounded upper articulating surface, creating a form of Hertz problem [Donzelli, P.S., Spilker, R.L., Ateshian, G.A., Mow, V.C. (1999) “Contact analysis of biphasic transversely isotropic cartilage layers and correlations with tissue failure”, Journal of Biomechanics 32, 1037–1047]. However, diarthrodial joints (shoulder, hip and knee) are equipped with peripheral structures (glenoid labrum, acetabular labrum and meniscus, respectively) that tend to deepen the joint contact and thus cause initial contact to be established at the periphery of the joint rather than “centrally”. The surface geometries are purposefully incongruent, and the incongruency has a significant effect on the stresses, pressures and pressure gradients inside the tissue. The models show the importance of the peripheral structures and the incongruency from a load-bearing perspective. Joint shapes must provide a compromise between demands for load-bearing, lubrication and the supply of nutrients to the chondrocytes of the cartilage and cells of the peripheral structures. Retention and repair of the functionality of these peripheral structures should be a prime consideration in any surgical treatment of an injured joint.  相似文献   

15.
Fatigue is a major risk factor for occupational ‘accidents’ and injuries, and involves dimensions of physical, mental, and muscular fatigue. These dimensions are largely influenced by temporal aspects of work schedules. The “Risk Index” combines four fatigue-related components of work schedules to estimate occupational ‘accident’ and injury risk based on empirical trends: shift type (morning, afternoon/evening, night), length and consecutive number, and on-shift rest breaks. Since its first introduction in 2004, several additional studies have been published that allow the opportunity to improve the internal and external validity of the “Risk Index”. Thus, we updated the model’s estimates by systematically reviewing the literature and synthesizing study results using meta-analysis. Cochrane Collaboration directives and MOOSE guidelines were followed. We conducted systematic literature searches on each model component in Medline. An inverse variance approach to meta-analysis was used to synthesize study effect sizes and estimate between-studies variance (‘heterogeneity’). Meta-regression models were conducted to explain the heterogeneity using several effect modifiers, including the sample age and sex ratio. Among 3,183 initially identified abstracts, after screening by two independent raters (95–98% agreement), 29 high-quality studies were included in the meta-analysis. The following trends were observed: Shift type. Compared to morning shifts, injury risk significantly increased on night shifts (RR = 1.36 [95%CI = 1.15–1.60], n = 14 studies), while risk was slightly elevated on afternoon/evening shifts, although non-significantly (RR = 1.12 [0.76–1.64], n = 9 studies). Meta-regressions revealed worker’s age as a significant effect modifier: adolescent workers (≤ 20 y) showed a decreased risk on the afternoon/evening shift compared to both morning shifts and adult workers (p < 0.05). Number of consecutive shifts. Compared to the first shift in a block of consecutive shifts, risk increased exponentially for morning shifts (e.g., 4th: RR = 1.09 [0.90–1.32]; n = 6 studies) and night shifts (e.g., 4th: RR = 1.36 [1.14–1.62]; n = 8 studies), while risk on afternoon/evening shifts appeared unsystematic. Shift length. Injury risk rose substantially beyond the 9th hour on duty, a trend that was mirrored when looking at shift lengths (e.g., >12 h: RR = 1.34 [1.04–1.51], n = 3 studies). Rest breaks. Risk decreased for any rest break duration (e.g., 31–60 min: RR = 0.35 [0.29–0.43], n = 2 studies). With regards to time between breaks, risk increased with every additional half hour spent on the work task compared to the first 30 min (e.g., 90–119 min: RR = 1.62 [1.00–2.62], n = 3 studies). Rest break duration and interval seem to interact such that with increasing duration, the time between breaks becomes irrelevant. The updated “Risk Index”. All four components were combined to form the updated model and the relative risk values estimated for a variety of work schedules. The resulting “Risk Map” shows regions of highest risk when rest breaks are not taken frequently enough (i.e. <4 h) or are too short (i.e. <30 min), when shift length exceeds 11 h, and when work takes place during the night (particularly for >3 consecutive night shifts). The “Risk Index” is proposed as an empirical model to predict occupational ‘accident’ and injury risk based on the most recent data in the field, and can serve as a tool to evaluate hazards and maximize safety across different work schedules.  相似文献   

16.
Objective: The purpose of this study was to examine both cross‐sectional and longitudinal associations between frequency of family dinner and overweight status in a large sample of 9‐ to 14‐year‐old children. Research Methods and Procedures: We studied a cohort of 7784 girls and 6647 boys, 9 to 14 years of age at baseline in 1996, participating in the Growing Up Today Study. From annual mailed surveys, we calculated BMI from self‐reported height and weight and assessed frequency of family dinner over the previous year. We defined “overweight” as age‐ and sex‐specific BMI >85th percentile. We performed multiple logistic regression analyses; the longitudinal analyses assessed the association of previous year family dinner consumption with 1‐year incidence of becoming overweight, using prospective data from 1996 through 1999. Results: At baseline in 1996, 16% of participants had family dinner “never or some days,” 40% on “most days,” and 44% “every day.” Across these categories, overweight prevalence for girls was 19.4%, 16.6%, and 16.7% and for boys was 24.6%, 23.3%, and 22.7%, respectively. In cross‐sectional analyses, adjusting for potential confounders, the odds of being overweight was 0.85 [95% confidence interval (CI): 0.76, 0.96] among children who ate family dinner on “most days” or “every day” compared with those who ate family dinner “never or some days.” In longitudinal multivariate models, the odds ratios between previous year frequency of eating family dinner and 1‐year incidence of becoming overweight were 0.95 (95% CI: 0.78, 1.16) and 1.04 (95% CI: 0.85, 1.27) for children who ate family dinner on “most days” and “every day,” respectively, compared with those who ate family dinner “never or some days.” Discussion: The frequency of eating family dinner was inversely associated with overweight prevalence at baseline but not with likelihood of becoming overweight in longitudinal analyses.  相似文献   

17.
Visual orientation in the greenhouse whitefly (Trialeurodes vaporariorum Westwood, Hemiptera: Aleyrodidae) is the result of “wavelength‐specific behaviours.” Green–yellow elicits “settling behaviour” while ultraviolet (UV) radiation initiates “migratory behaviour.” The only available physiological study of the photoreceptors' spectral efficiency showed peaks in the green and the UV range and whitefly vision was said to be dichromatic so far. In order to study the visual behaviour of T. vaporariorum, 19 narrow‐bandwidth light emitting diodes (LEDs) covering the UV‐A and visible range were used in combination with light scattering acrylic glass screens in a small‐scale choice arena under greenhouse conditions. Multiple‐choice and dual‐choice assays were performed, resulting in LED‐based behavioural action spectra of settling (green) and migratory behaviour (UV). A potential inhibitory blue–green chromatic mechanism was studied by combining yellow with different bluish LEDs. Intensity dependencies were illustrated by changing LED intensities. Regarding the “settling response,” highest attraction was achieved by a green LED with a centroid wavelength of 550 nm, while a blue LED with 469 nm proved to be most inhibitory. Besides this inhibitory interaction, an intensity dependence was observed within the action spectrum in the green–yellow range. “Migratory behaviour” was elicited the most by the UV LED with the shortest available wavelength of 373 nm. The results provide compelling behavioural evidence for the presence of a green and a yet undescribed blue sensitive photoreceptor and a blue–green opponent mechanism. Furthermore, empirical colour choice models were built and receptor peaks were estimated around 510–520 nm (green), 480–490 nm (blue) and 340–370 nm (UV). Consequently, a trichromatic receptor setup is suggested for T. vaporariorum.  相似文献   

18.
Background and Aim: The prevalence of Helicobacter pylori infection is exceptionally low among the Malays in the north‐eastern region of Peninsular Malaysia. The reasons are unknown. Our aim was to compare environmental factors that differed in relation to H. pylori prevalence among Malays born and residing in Kelantan. Methods: A case–control study was conducted among Malays in Kelantan who underwent upper endoscopy between 2000 and 2008. Helicobacter pylori status was determined by gastric histology. Sociocultural and dietary factors were assessed using a validated investigator‐directed questionnaire administered after 2008, and the data were analyzed using logistic regression analysis. Results: The study group consisted of 161 subjects (79 H. pylori positive and 82 controls). Univariable analysis identified five poor sanitary practices associated with an increased prevalence of H. pylori infection: use of well water, use of pit latrine, less frequent boiling of drinking water, and infrequent hand wash practice after toilet use and before meals. Multivariable logistic regression analysis identified three variables inversely associated with H. pylori infection: frequent consumption of tea (OR: 0.023, 95% CI: 0.01–0.07), frequent use of “budu” or local anchovy sauce (OR: 0.09, 95% CI: 0.1–0.7), and frequent use of “pegaga” or centenella asiatica (OR: 0.25, 95% CI: 0.1–0.65). Conclusions: Under the assumption that sanitary, sociocultural, and dietary habits have not changed over the years, we can conclude that an increased risk of H. pylori was associated with unsanitary practices whereas protection was associated with consumption of tea and locally produced foods, “pegaga” and “budu.” These dietary factors are candidates for future study on the effects on H. pylori transmission.  相似文献   

19.
Niv Y  Hazazi R 《Helicobacter》2008,13(1):56-61
Objective: Recurrence of Helicobacter pylori infection after eradication is rare in developed countries and more frequent in developing countries. Most recurrent cases are attributed to recrudescence (recolonization of the same strain within 12 months) rather than to reinfection (colonization with a new strain after more than 12 months). The aim of the study was to analyze recurrence rates in developed and developing countries and to deduce the relative roles of recrudescence and reinfection. Methods: The PubMed database was searched up to January 31, 2007 using the keywords “Helicobacter pylori” or “H. pylori” and “recurrence” or “recrudescence,” or “reinfection.” Only prospective case studies in adults that used the 13C‐urea breath test (13CUBT) were included. Meta‐analyses were performed with statdirect Statistical software, version 2.6.1, StatsDirect Ltd, Chesire, UK. Results: The literature search yielded 10 studies of H. pylori recurrence in developed countries (3014 patients followed for 24–60 months) and 7 studies in developing countries (2071 patients followed for 12–60 months). The calculated annual recurrence rates were 2.67% and 13.00%, respectively. Nested meta‐analysis of cases with a longer follow‐up after eradication revealed an annual recurrence rate of 1.45% (RR 0.54) in developed countries and 12.00% (RR 0.92) in developing countries. Conclusions: The similarity of the annual recurrence rates during the first year after eradication and the annual recurrence rates in the second year after successful eradication in developing countries supports reinfection as the main cause in the second period. Therefore, a different approach for follow‐up of H. pylori eradication may be needed between developed and developing countries.  相似文献   

20.
Currently, there are three recognized ecotypes (or species) of killer whales (Orcinus orca) in Antarctic waters, including type B, a putative prey specialist on seals, which we refer to as “pack ice killer whale” (PI killer whale). During January 2009, we spent a total of 75.4 h observing three different groups of PI killer whales hunting off the western Antarctic Peninsula. Observed prey taken included 16 seals and 1 Antarctic minke whale (Balaenoptera bonaerensis). Weddell seals (Leptonychotes weddellii) were taken almost exclusively (14/15 identified seal kills), despite the fact that they represented only 15% of 365 seals identified on ice floes; the whales entirely avoided taking crabeater seals (Lobodon carcinophaga; 82% relative abundance) and leopard seals (Hydrurga leptonyx; 3%). Of the seals killed, the whales took 12/14 (86%) off ice floes using a cooperative wave‐washing behavior; they produced 120 waves during 22 separate attacks and successfully took 12/16 (75%) of the Weddell seals attacked. The mean number of waves produced per successful attack was 4.1 (range 1–10) and the mean attack duration was 30.4 min (range 15–62). Seal remains that we examined from one of the kills provided evidence of meticulous postmortem prey processing perhaps best termed “butchering.”  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