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Likely Explanation (likely + explanation)
Selected Abstractsbmp2b and bmp4 are dispensable for zebrafish tooth developmentDEVELOPMENTAL DYNAMICS, Issue 10 2010Sarah B. Wise Abstract Bone morphogenetic protein (Bmp) signaling has been shown to play important roles in tooth development at virtually all stages from initiation to hard tissue formation. The specific ligands involved in these processes have not been directly tested by loss-of-function experiments, however. We used morpholino antisense oligonucleotides and mutant analysis in the zebrafish to reduce or eliminate the function of bmp2b and bmp4, two ligands known to be expressed in zebrafish teeth and whose mammalian orthologs are thought to play important roles in tooth development. Surprisingly, we found that elimination of function of these two genes singly and in combination did not prevent the formation of mature, attached teeth. The mostly likely explanation for this result is functional redundancy with other Bmp ligands, which may differ between the zebrafish and the mouse. Developmental Dynamics 239:2534,2546, 2010. © 2010 Wiley-Liss, Inc. [source] Patchy Myocardial Fibrosis 20 Years after Radiation TherapyECHOCARDIOGRAPHY, Issue 1 2007Rachael A. Wyman M.D. We describe a case of a young woman diagnosed with Ewings sarcoma at age 8 and treated with adriamycin and radiation therapy. Twenty years later the patient has a cardiomyopathy and a focal area of patchy infiltration of fibrotic tissue along the left ventricle and atrium. Although fibrosis due to radiation exposure has been demonstrated on biopsy and autopsy studies, we are not aware of previous reports of echocardiographic demonstration of this finding. The most likely explanation for the fibrosis location is the left posterolateral direction of the radiation beam. [source] Distribution, zoogeography and biology of the Murchison River hardyhead (Craterocephalus cuneiceps Whitley, 1944), an atherinid endemic to the Indian Ocean (Pilbara) Drainage Division of Western AustraliaECOLOGY OF FRESHWATER FISH, Issue 3 2005M. G. Allen Abstract , The Murchison River hardyhead (Craterocephalus cuneiceps) is endemic to the extremely arid Indian Ocean (Pilbara) Drainage Division of Western Australia, where it is found in the Greenough, Hutt, Murchison, Wooramel, Gascoyne and DeGrey rivers, but is absent from numerous rivers within its range. The most likely explanation for the disjunct contemporary distribution is that C. cuneiceps has simply never inhabited the rivers from which it is conspicuously absent (e.g. Ashburton and Fortescue). Biogeographical, geological and palaeoclimatic evidence is presented to support this hypothesis. In the Murchison River, breeding was extremely protracted with recruitment occurring throughout the year. The largest female and male specimens captured were 96 mm total length (TL; 7.73 g) and 86 mm TL (5.57 g), respectively. Sex ratio was 1.09 females:1 male. Batch fecundity ranged from 46 to 454 (mean 167.5 ± 25.7 SE). Estimates for the length at which 50 and 95% of females first spawned were 36.4 and 44.3 mm TL, respectively. Craterocephalus cuneiceps is essentially a detritivore, but also feeds on aquatic invertebrates. Rainfall in the Murchison River catchment is unpredictable and pH, salinity and temperature are variable. A specialised diet, small size and young age at maturity and protracted spawning period, coupled with serial spawning and high fecundity, allows the numerical dominance of this species in competitive, harsh, arid and unpredictable desert environments. Resumen 1. Craterocephalus cuneiceps es una especie endémica de las cuencas del Océano Indico (i.e., Pilbara) de Australia Occidental. Se encuentra en los ríos Greenough, Hutt, Murchison, Wooramel, Gascoyne y DeGrey pero está ausente en numerosos ríos dentro de su área de distribución. La explicación más probable para esta distribución separada en la actualidad es que C. cuneiceps no ha habitado nunca los ríos en los que está ausente tales como los ríos Ashburton y Fortescue. Presentamos evidencia bio-geográfica, geológica y paleo-climática para soportar esta hipótesis. 2. En el río Murchison, la reproducción es extremadamente prolongada con reclutamiento a lo largo de todo el año. Los mayores machos y hembras capturados alcanzaron 96 mm LT (7.73 g) y 86 mm LT (5.57 g), respectivamente. La proporción de sexos fue 1.09 hembras: 1 macho. La fecundidad varió entre 46 y 454 (media 167.5 ± 25.7 SE) y la longitudes a la que el 50 y el 95% de las hembras se reproducen por primera vez alcanzaron 36.4 y 44.3 mm LT, respectivamente. 3. C. cuneiceps es esencialmente detritívoro pero también se alimenta de invertebrados acuáticos. La lluvia sobre la cuenca del río Murchison es impredecible y el pH, la salinidad y la temperatura son variables. Una dieta especializada, pequeño tamaño, una edad joven en la madurez, y un período reproductivo prolongado, ademos de una freza seriada y alta fecundidad, permiten la dominancia numérica de la especie en ambientes competitivos, duros, áridos e impredecibles. [source] Impact of Collimonas bacteria on community composition of soil fungiENVIRONMENTAL MICROBIOLOGY, Issue 6 2009Sachie Höppener-Ogawa Summary The genus Collimonas consists of soil bacteria that have the potential to grow at the expense of living fungal hyphae. However, the consequences of this mycophagous ability for soil fungi are unknown. Here we report on the development of fungal communities after introduction of collimonads in a soil that had a low abundance of indigenous collimonads. Development of fungal communities was stimulated by addition of cellulose or by introducing plants (Plantago lanceolata). Community composition of total fungi in soil and rhizosphere and of arbuscular mycorrhizal fungi in roots was examined by PCR-DGGE. The introduction of collimonads altered the composition of all fungal communities studied but had no effects on fungal biomass increase, cellulose degrading activity or plant performance. The most likely explanation for these results is that differences in sensitivity of fungal species to the presence of collimonads result in competitive replacement of species. The lab and greenhouse experiments were complemented with a field experiment. Mesh bags containing sterile sand with or without collimonads were buried in an ex-arable field and a forest. The presence of collimonads had an effect on the composition of fungi invading these bags in the ex-arable site but not in the forest site. [source] Dichlorodiphenyltrichloroethane in the aquatic ecosystem of the Okavango Delta, Botswana, South AfricaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Bontle Mbongwe Abstract Concentrations of DDT and its metabolites were measured in water, plants, invertebrates, and fish from lagoons in the Okavango Delta, Botswana (Africa), where DDT has been used for approximately 50 years. The sampling area was sectioned to distinguish spraying for malaria and for African sleeping sickness. Average concentrations of total DDT (sum of DDT and its metabolites) in the Okavango ranged from 0.009 ng/L in water to 18.76 ng/g wet weight in fish. These levels are approximately 1% of those found in piscivorous fish from temperate North America. The dichlorodiphenyl ethylene (DDE) metabolite was the most abundant fraction of total DDT. Although total DDT concentrations were higher in areas treated for malaria than areas treated for sleeping sickness, these concentrations were likely driven by factors other than the historic application of the pesticide. Equilibration with air concentrations is the most likely explanation for these levels. Since the mean annual temperature exceeds the temperature of vaporization of DDT, this research points to the need for reliable transport models. Our results showed that total DDT concentration in fish was best explained by lipid content of the fish and trophic position inferred by ,15N, regardless of DDT application history in those areas. The reservoir above Gaborone Dam, an area downstream of the Okavango but where DDT had not been used, was sampled to compare total DDT levels to the treated areas. The two species (a herbivorous threespot talapia and the omnivorous sharptooth catfish) from Gaborone had levels higher than those found in the Okavango Delta, but these differences can again be explained using trophic position inferred by ,15N rather than by fish size or location. [source] Metachronous testicular teratoma, testicular seminoma and papillary thyroid carcinoma occurring in a single individual: a report of two unrelated casesEUROPEAN JOURNAL OF CANCER CARE, Issue 5 2010A.A. SYED mbbs, specialist registrar in endocrinology SYED A.A., JONES N.A.G., BLISS R.D., ROBERTS J.T., MALLICK U.K., JOHNSON S.J., DOUGLAS S.F., PERROS P. & QUINTON R. (2010) European Journal of Cancer Care19, 701,702 Metachronous testicular teratoma, testicular seminoma and papillary thyroid carcinoma occurring in a single individual: a report of two unrelated cases We describe two unrelated men who both developed teratomas in one testis followed by seminomas in the contralateral testis followed by papillary thyroid carcinomas. Neither man had a family history of cancers. Although random occurrence is possible, genetic predisposition and/or environmental influence would seem a likely explanation for this previously unreported combination of tumours. [source] The effect of a closed area and beach seine exclusion on coral reef fish catchesFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2001T. R. McClanahan Fish landing data from the Mombasa Marine National Park (MNP) and a marine reserve exploited by various gears were studied over a 5-yr period to determine the influence of the closed area and different gears in fisheries. The number fishing and boats per landing site was constant, but total and catch per unit effort progressively declined in all sites on an annual basis irrespective of the existence of a marine reserve, exclusion of the beach seines or use of gear. Differences between landing sites were most pronounced when analysed on a catch per area as opposed to the more standard catch per fisherman, suggesting compensation in human effort when catches decline. A marine reserve next to a closed area that excluded beach seines had the highest catch per area (5.5 kg ha,1 month,1) despite having the highest density of fishermen (0.07 ± 0.02 fishermen ha,1 month,1). The annual rate of decline in the catch was lower than the other sites at around 250 g day,1 compared with 310,400 g day,1 in the other sites. One landing site, which excluded beach seine landings for more than 20 yrs, had a high catch per area (,5.3 kg ha,1 month,1), but after experiencing a doubling in the effort of other gears (line, speargun and trap), the catch per fisherman and area were reduced. Environmental or habitat degradation and excessive effort remain the most likely explanation for the overall declines in catch from 1995 to 1999. Closed areas and beach seine exclusion have the potential to increase catch rates, but the first often reduces the total fishing area and possibly leads to a loss of total catch, at least on a time scale of less than 10 yrs. The exclusion of beach seines can lead to an increase in other gear types that can also cause reductions in catch. [source] Wing wear, aerodynamics and flight energetics in bumblebees (Bombus terrestris): an experimental studyFUNCTIONAL ECOLOGY, Issue 4 2001A. Hedenström Summary 1,Previous work has shown that wing wear increases mortality rate in bumblebees. Two proximate explanations have been suggested to account for this: increased energy flight costs and increased predation risk due to reduced manoeuvrability. 2,Wing wear was mimicked by experimentally clipping the forewing distal trailing edge, causing a 10% wing area reduction. Experimental and sham control bumblebees were induced to hover in a flight respirometry chamber for measuring metabolic rate of hovering. Simultaneous video and sound recordings were taken for wingbeat kinematic data required for an aerodynamic analysis. 3,In the experimental group with reduced wing area we measured increased wingbeat frequency, lift coefficient and induced power, but a reduced profile power. The mechanical power output, assuming perfect elastic storage in the flight system, remained largely unchanged after the wing-trimming treatment. 4,Metabolic flight costs (CO2 production rate) did not increase significantly in the reduced wing area group, which is in line with the aerodynamic power output. 5,Our results indicate that an increase of flight cost due to wing wear is not a likely explanation for increased mortality rate in bumblebees. Wing wear may, however, affect escape performance from predators. [source] Using Temperature to Test Models of Flow Near Yucca Mountain, NevadaGROUND WATER, Issue 5 2003Scott Painter Ground water temperatures in the fractured volcanic aquifer near Yucca Mountain, Nevada, have previously been shown to have significant spatial variability with regions of elevated temperatures coinciding roughly with near-vertical north-south trending faults. Using insights gained from one-dimensional models, previous investigators have suggested upwelling along faults from an underlying aquifer as a likely explanation for this ground water temperature pattern. Using a three-dimensional coupled flow and heat-transport model, we show that the thermal high coinciding with the Paintbrush fault zone can be explained without significant upwelling from the underlying aquifer. Instead, the thermal anomaly is consistent with thermal conduction enhanced slightly by vertical ground water movement within the volcanic aquifer sequence. If more than -400 m3/day of water enters the volcanic aquifer from below along a 10 km fault zone, the calculated temperatures at the water table are significantly greater than the measured temperatures. These results illustrate the potential limitations in using one-dimensional models to interpret ground water temperature data, and underscore the value in combining temperature data with fully coupled three-dimensional simulations. [source] Training as a vehicle to empower carers in the community: more than a question of information sharingHEALTH & SOCIAL CARE IN THE COMMUNITY, Issue 2 2001MSc (Econ), Nicholas Clarke BSc MSc Abstract Much confusion still surrounds the concept of empowerment and how it is to be translated into practice within the context of community care for service users and carers. A major limitation has been the tendency to treat empowerment as synonymous with participation in decision-making with little attention given to the ,ecological' model of empowerment where linkages have been found between community participation and measures of psychological empowerment. Training has been suggested as a means through which carers might become empowered, yet to date little empirical evidence has appeared within the literature to support this proposition. This study investigated whether attendance on a training programme to empower carers resulted in improvements in carers' levels of perceived control, self-efficacy and self-esteem as partial measures of psychological empowerment. The findings demonstrated that whereas carers' knowledge of services and participation increased as a result of the programme, no changes were found in measures of carer empowerment. The failure to consider how training needs to be designed in order to achieve changes in individual competence and self-agency are suggested as the most likely explanation for the lack of change observed in carers' psychological empowerment. It is suggested that community care agencies should focus greater energies in determining how the policy objectives of empowerment are to be achieved through training, and in so doing make far more explicit the supposed linkages between training content, design, and its posited impact on individual behaviour or self-agency. [source] Age-dependent reproductive performance in Northern Goshawks Accipiter gentilisIBIS, Issue 1 2003Jan Tøttrup Nielsen The age-specific reproductive performance of Northern Goshawks Accipiter gentilis was studied over 22 years in Denmark. The age of the breeding female in relation to the number of young raised was known in 929 breeding attempts, while the age of both the male and the female was known in 496 breeding attempts. The number of fledglings raised per breeding attempt increased with both male and female age, but only for females was it possible to conduct a detailed analysis of this age-dependent relationship. The annual production of fledglings increased with female age from 1 to 7 years of age, whereupon it started to decline. A longitudinal analysis showed that this mean population trend could be attributed to similar age-related trends in individual females. Previous breeding experience did not influence the number of fledglings produced by individual females, and poorly performing females apparently survived with the same probability as well performing ones. The most likely explanation for the age-dependent reproductive performance in the observed Goshawk population appeared to be age-related improvements in competence, such as foraging efficiency. [source] How work-place conditions, environmental toxicants and lifestyle affect male reproductive function,INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 5 2002Jens Peter Bonde Summary Major temporal and geographical shifts in male reproductive function is presently an issue worldwide. The hormonal disruption hypothesis has achieved considerable attention but epidemiological evidence in support of the theory is lacking. Several occupational hazards to male reproductive function are known but exposure prevalences are hardly sufficient to play a role for reduced sperm count in the general male population. Sedentary work may be an exception. Perhaps prolonged time in the sedentary position exhausts the testicular heat regulation. But so far studies addressing implications of the heat hypothesis in the general population are few. Neither change of sexual behaviour nor reduced period of sexual continence seems to be a likely explanation. Tobacco smoking and consumption of caffeine and alcoholic beverages in adulthood have a rather marginal impact on spermatogenesis and can hardly explain major shifts or regional differences in male reproductive health. However, prenatal effects following smoking during pregnancy might play a role because we have witnessed a smoking epidemic among fertile women in some countries during the second half of the twentieth century. Moreover, if genetic factors play more than a marginal role for testicular function and sperm count, pregnancy planning resulting in reduced family size during the past 100 years could possibly explain a decline in semen quality because the most fertile part of the population reproduce less while the subfertile probably continue to get a limited number of children. [source] Incidence rates of hepatocellular carcinoma in the U.S. and Denmark: Recent trendsINTERNATIONAL JOURNAL OF CANCER, Issue 7 2007Peter Jepsen Abstract Hepatocellular carcinoma (HCC) incidence rates vary by gender, age, time and place. Geographic differences in gender-, age- and time-specific HCC incidence rates may improve the understanding of HCC risk factors. We computed annual standardized HCC incidence rates for the United States (U.S.) 1978,2004 and for Denmark 1978,2003. Among U.S. white men aged 45,59 the HCC incidence rates were comparable to the Danish rates until 1995, but more than tripled over the following 8 years to become over 2.5-fold higher than the Danish rate by 2003, with an additional small increase in 2004. HCC rates in black U.S. men aged 45,59 also increased sharply after 1995. Among women aged 45,59 the U.S. HCC rates were elevated in recent years, but did not show the sharp increase after 1995 observed among men; the Danish rates showed a decreasing trend throughout 1978,2003. U.S. rates in the 60,74 years age groups showed a protracted and gradual increase with no evidence of a sharp increase after 1995. In the 60,74 years age group, rates for Danish men were comparable to those for U.S. white men, but rates for Danish women decreased. The U.S. prevalence rates of hepatitis C virus (HCV) infection are 2.1 and 1.1% for men and women, respectively, the Danish 0.2%. The disparity in HCV prevalence is the most likely explanation for the differences between Danish and U.S. trends in HCC incidence. Intravenous drug use and blood transfusions are the major sources of HCV, and we suggest that increased HCV infection prevalence among Vietnam era military veterans may contribute to the earlier and steeper HCC incidence increase for U.S. men than for U.S. women. © 2007 Wiley-Liss, Inc. [source] CASSCF study into the mechanism for predissociation of the allyl radicalINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2006Milena Shahu Abstract A theoretical study has been carried out on the allyl radical in its ground and first excited electronic states. Complete active space self-consistent field (CASSCF) calculations show the presence of a conical intersection between the ground and first excited electronic states (,400 cm,1 above the adiabatic excited state energy), reached by decreasing the CCC angle and twisting the CC bonds. The presence of this conical intersection provides a likely explanation for the very rapid predissociation in the excited electronic state. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Combined effects of climate and biotic interactions on the elevational range of a phytophagous insectJOURNAL OF ANIMAL ECOLOGY, Issue 1 2008Richard M. Merrill Summary 1The ranges of many species have expanded in cool regions but contracted at warm margins in response to recent climate warming, but the mechanisms behind such changes remain unclear. Particular debate concerns the roles of direct climatic limitation vs. the effects of interacting species in explaining the location of low latitude or low elevation range margins. 2The mountains of the Sierra de Guadarrama (central Spain) include both cool and warm range margins for the black-veined white butterfly, Aporia crataegi, which has disappeared from low elevations since the 1970s without colonizing the highest elevations. 3We found that the current upper elevation limit to A. crataegi's distribution coincided closely with that of its host plants, but that the species was absent from elevations below 900 m, even where host plants were present. The density of A. crataegi per host plant increased with elevation, but overall abundance of the species declined at high elevations where host plants were rare. 4The flight period of A. crataegi was later at higher elevations, meaning that butterflies in higher populations flew at hotter times of year; nevertheless, daytime temperatures for the month of peak flight decreased by 6·2 °C per 1 km increase in elevation. 5At higher elevations A. crataegi eggs were laid on the south side of host plants (expected to correspond to hotter microclimates), whereas at lower sites the (cooler) north side of plants was selected. Field transplant experiments showed that egg survival increased with elevation. 6Climatic limitation is the most likely explanation for the low elevation range margin of A. crataegi, whereas the absence of host plants from high elevations sets the upper limit. This contrasts with the frequent assumption that biotic interactions typically determine warm range margins, and thermal limitation cool margins. 7Studies that have modelled distribution changes in response to climate change may have underestimated declines for many specialist species, because range contractions will be exacerbated by mismatch between the future distribution of suitable climate space and the availability of resources such as host plants. [source] Oilseed rape crops distort plant,pollinator interactionsJOURNAL OF APPLIED ECOLOGY, Issue 1 2010Tim Diekötter Summary 1. New incentives at the national and international level frequently lead to substantial structural changes in agricultural landscapes. Subsidizing energy crops, for example, recently fostered a strong increase in the area cultivated with oilseed rape Brassica napus across the EU. These changes in landscape structure affect biodiversity and associated ecosystem services. 2. Mass-flowering oilseed rape has been shown to positively affect colony growth and densities of bumblebees, which may enhance pollination services in agroecosystems. Not considered, however, have been species-specific traits of pollinators resulting in disproportionate benefits from these recurrent resource pulses. A subsequent community shift towards the subsidized species potentially distorts plant,pollinator interactions in the surrounding landscape. 3. We analysed the effects of mass-flowering crops on the abundance of legitimate long-tongued bumblebee pollinators, nectar robbing by illegitimate short-tongued bumblebees and seed set in the long-tubed flowers of red clover Trifolium pratense in 12 landscape sectors with differing amounts of oilseed rape. 4. Densities of long-tongued bumblebees visiting long-tubed plants decreased with increasing amounts of oilseed rape. The simultaneous increase of nectar robbing suggests that resource depletion is a likely explanation for this decline which may lead to a distortion in plant,pollinator interactions. The decline in long-tongued bumblebees, however, did not result in an immediate effect on seed set. In contrast, seed set increased with increasing amounts of semi-natural habitats, indicating the positive effects of these habitats on the legitimate long-tongued pollinators. 5.Synthesis and applications. Accounting for species-specific traits is essential in evaluating the ecological impacts of land-use change. The disproportional trait-specific benefits of increasing oilseed rape to short-tongued bumblebees may abet an increasingly pollinator-dependent agriculture but simultaneously threaten the more specialized and rare long-tongued species and their functions. Semi-natural habitats were found to positively affect seed set in long-tubed plants indicating that they can counteract the potentially distorting effects of transient mass-flowering crops on plant,pollinator interactions in agroecosystems. Future agri-environmental schemes should aim to provide diverse and continuous resources matching trait-specific requirements of various pollinators in order to avoid resource competition. Thereby they harmonize the economic interest in abundant pollinators and the conservation interest in protecting rare species. [source] Bacillus megaterium spore germination is influenced by inoculum sizeJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002M.L. Caipo Aims:,The effect of spore density on the germination (time-to-germination, percent germination) of Bacillus megaterium spores on tryptic soy agar was determined using direct microscopic observation. Methods and Results:,Inoculum size varied from approximately 103 to 108 cfu ml,1 in a medium where pH=7 and the sodium chloride concentration was 0·5% w/v. Inoculum size was measured by global inoculum size (the concentration of spores on a microscope slide) and local inoculum size (the number of spores observed in a given microscope field of observation). Both global and local inoculum sizes had a significant effect on time-to-germination (TTG), but only the global inoculum size influenced the percentage germination of the observed spores. Conclusions:,These results show that higher concentrations of Bacillus megaterium spores encourage more rapid germination and more spores to germinate, indicating that low spore populations do not behave similarly to high spore populations. Significance and Impact of the Study:,A likely explanation for the inoculum size-dependency of germination would be chemical signalling or quorum sensing between Bacillus spores. [source] Absence of a specific subgingival microflora in adults with Down's syndromeJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2001W. Reuland-Bosma Abstract Background: Periodontal disease in Down's syndrome (DS) is generally characterized by a high degree of bone loss. Bone loss of 5 mm or more is observed in 70% of these subjects. Among DS subjects, considerable differences in disease progression occur. So far, no studies have been conducted in which specific properties of the subgingival microflora have been related to the condition observed. Aims: To investigate (1) the subgingival microflora in DS subjects and other mentally retarded (control) individuals which were matched to the utmost and (2) to investigate the subgingival microflora of a "low-risk" and a " high-risk" group formed in DS subjects. Material and Methods: 17 DS subjects and 17 control subjects were matched with respect to age, plaque level and bleeding on probing. In addition, the DS group was divided in a "low-risk" group (0,2 teeth lost due to periodontal disease n=6) and a "high-risk"group (6,13 teeth lost due to periodontal disease n=11). Prevalence and proportions of the putative periodontal pathogens Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Peptostreptococcus micros, Fusobacterium nucleatum and Campylobacter rectus in the subgingival plaque were determined using anaerobic culture techniques. No differences in the prevalence of distinct suspected periodontopathic bacteria and bacterial subgingival composition between the DS group and the control group could be established. Also no differences in the prevalence of the seven investigated microbial species between the "low-risk" and the "high-risk" group were observed. Conclusions: Because of the lack of differences in microflora between the DS group and the control group, a specific effect of the microbiological composition in the periodontal status of subjects with DS can be excluded in this population. Host factors constitute the more likely explanation of the differences observed in DS. Zusammenfassung Basis: Die parodontale Erkrankung beim Down Syndrom (DS) ist allgemein durch einen hohen Grad von Knochenverlust charakterisiert. Knochenverlust von 5 mm und mehr wird bei 70% der Personen beobachtet. Unter den DS Personen bestehen beträchtliche Differenzen in der Erkrankungsprogression. Bis heute sind keine Studien durchgeführt worden, in welchen die spezifischen Eingenschaften der subgingivalen Mikroflora in Beziehung zu den Bedingungen beobachtet wurden. Ziele: Untersuchung (1) der subgingivalen Mikroflora bei DS Personen und anderen mental retardierten (Kontrollen) Personen, die zu einer größten gemischt wurden und (2) der subgingivalen Mikroflora von Gruppen mit "geringem Risiko" und Gruppen mit "hohem Risiko" bei DS Personen. Material und Methoden: 17 DS Personen mit 17 Kontrollpersonen wurden im Hinblick auf Alter, Plaquemenge und Blutung auf Provokation eingeteilt. Zusätzlich wurde die DS Gruppe in "geringes Risiko" (0,2 Zähne infolge von parodontaler Erkrankung verloren, n=6) und in "hohes Risiko" (6,13 Zähne infolge parodontaler Erkrankung verloren, n=11) eingeteilt. Das Vorkommen und die Relationen von putativen parodontalen Pathogenen Actinobacillus actinomycetemcomitants, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Peptostreptococcus micros, Fusobacterium nucleatum und Campylobacter rectus in der subgingivalen Plaque wurden mit anaerober Kulturtechnik bestimmt. Ergebnisse: Es konnten keine Differenzen in der Prävalenz der bezeichneten parodontopathogenen Bakterien und der bakteriellen subgingivalen Zusammensetzung zwischen DS Gruppe und der Kontrollgruppe beobachtet werden. Auch zwischen der Gruppe "geringes Risiko" und "hohes Risiko" wurden keine Differenzen in der Prävalenz der 7 untersuchten Spezies beobachtet. Schlußfolgerungen: Weil keine Differenzen in der Mikroflora zwischen DS Gruppe und der Kontrollgruppe vorhanden sind, kann ein spezifischer Effekt der mikrobiologischen Zusammensetzung beim parodontalen Status der Personen mit DS in dieser Population ausgeschlossen werden. Für die Erklärung der Differenzen, die bei den DS Personen beobachtet werden, sind die Wirtsfaktoren mehr wahrscheinlich. Résumé Origine: La maladie parodontale lors du syndrôme de Down (DS) est généralement caractérisée par une importante perte osseuse. Cette perte osseuse atteint 5 mm ou plus chez 70% de ces malades. Parmi les sujets DS, des différences considérables dans la progression de cette maladie se manifestent. Aucune étude n'a encore été entreprise dans laquelle la microflore sous-gingivale a été mise en relation avec les conditions observées. But: Le but de cette étude a été (1) d'analyser la microflore sous-gingivale chez les sujets DS et d'autres retardés mentaux servant de contrôles et (2) mieux connaître la microflore sous-gingivale chez les groupes de patients DS avec faible et haut risques. Matériaux et méthodes: 17 sujets DS et 17 sujets contrôles ont été analysés de manière parallèle en fonction de l'âge, du niveau de plaque dentaire et du saignement au sondage. De plus, le groupe DS était scindé en deux sous-groupes: "petit risque" (0 à 2 dents perdues pour cause de maladie parodontale; n=6), et "haut risque" (6 à 13 dents perdues; n=11). La fréquence globale et les proportions de pathogènes parodontaux putatifs l'Actinobacillus actinomycetemcomitans, le Porphyromonas gingivalis, le Prevotella intermedia, le Bacteroides forsythus, le Peptostreptococcus micros, le Fusobacterium nucleatum et le Campylobacter rectus dans la plaque sous-gingivale ont été déterminés en utilisant des techniques de culture anaérobie. Résultats: Aucune différence dans la fréquence globlale de ces bactéries ni dans la composition de la flore sous-gingivale n'a été trouvée entre le groupe DS et le groupe contrôle. Il n'y avait également aucune différence entre les sous-groupes à faible et à haut risques. Conclusions: Parce qu'aucune différence n'a été décelée dans la microflore entre les groupes DS et contrôle, aucun effet spécifique de leur flore sous-gingivale ne pourrait être responsable; les facteurs de l'hôte constituent très vraisemblablement l'explication des différences observées chez les sujets DS. [source] Assessing the extent of genome-wide intralocus sexual conflict via experimentally enforced gender-limited selectionJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2008E. H. MORROW Abstract Intralocus sexual conflict, which occurs when a trait is selected in opposite directions in the two sexes, is a taxonomically widespread phenomenon. The strongest genetic evidence for a gender load due to intralocus sexual conflict comes from the Drosophila melanogaster laboratory model system, in which a negative genetic correlation between male and female lifetime fitness has been observed. Here, using a D. melanogaster model system, we utilize a novel modification of the ,middle class neighbourhood' design to relax selection in one sex, while maintaining selection in the other. After 26 generations of asymmetrical selection, we observed the expected drop in fitness of the non-selected sex compared to that of the selected sex, consistent with previous studies of intralocus sexual conflict in this species. However, the fitness of the selected sex also dropped compared to the base population. The overall decline in fitness of both the selected and the unselected sex indicates that most new mutations are harmful to both sexes, causing recurrent mutation to build a positive genetic correlation for fitness between the sexes. However, the steeper decay in the fitness of the unselected sex indicates that a substantial number of mutations are gender-limited in expression or sexually antagonistic. Our experiment cannot definitively resolve these two possibilities, but we use recent genomic data and results from previous studies to argue that sexually antagonistic alleles are the more likely explanation. [source] Effects of fish size, time-to-fatigue and turbulence on swimming performance: a case study of Galaxias maculatusJOURNAL OF FISH BIOLOGY, Issue 6 2003V. I. Nikora A simple relationship for the inanga Galaxias maculatus swimming velocity is suggested and tested in low and high turbulence channels. The relationship connects the swimming velocity with fish Reynolds and Froude numbers and can be used in both ecological analysis (e.g. habitat requirements) and management strategies (e.g. fishways design). Contrary to some previous studies and intuition, effects of turbulence on swimming performance appeared to be negligible. The most likely explanation for this result relates to mechanics of fish,turbulence interactions that may be dependent on both the turbulence scales and energy. The data suggest that future studies of turbulence effects on fish behaviour should involve, in addition to turbulence energetics, consideration of fish dimensions in relation to the spectrum of turbulence scales. [source] Gains and structural effects of exploiting scale-economies in Norwegian dairy productionAGRICULTURAL ECONOMICS, Issue 2 2001Knut Løyland Dairy production; Economies of scale; Cost functions; Technical change Abstract In this paper, we present calculations of the economic gains in terms of reduced costs by exploiting scale-economies in dairy production in Norway, and the effect this would have had on the number of farms. We also explore whether or not optimal scale and unexploited scale-economies change over time due to scale-augmenting technical change. The analysis is based on homothetic cost functions estimated by means of data for individual dairy farms for the period 1972,1996. For 1972, we find that, by full exploitation of scale-economies, the costs could have been reduced by almost 40%, while the number of farms would have been reduced by more than 85%. The number of small farms has been substantially reduced in the period considered. This fact, combined with small scale-augmenting technical change, implies that the gains and structural effects of exploiting scale-economies have decreased over time. In 1996, costs could have been reduced by close to 30% by full exploitation of scale-economies, while the number of farms would have been reduced by slightly more than 70%. Thus, both gains and structural effects are substantially less than in 1972. Nevertheless, the calculated gains for 1996 make almost 5 billion NOK. This corresponds almost exactly to the total public support to the dairy farms in 1996. The unexploited scale-economies are largely due to the agricultural policy. Thus, a substantial share of the same can be considered as part of the,price' the Norwegian society has to pay for this policy. In addition, there are likely to be large hidden costs of this policy due in particular to the quota system and other direct production regulations. They imply that technical innovations and other efficiency-improving investments requiring increased production to be profitable are not carried out. This is the more likely explanation for the extremely poor efficiency development in Norwegian dairy production in the period studied. [source] SIZE INCREMENTS DUE TO INTERINDIVIDUAL FUSIONS: HOW MUCH AND FOR HOW LONG?,JOURNAL OF PHYCOLOGY, Issue 4 2010Bernabé Santelices Size increments following interindividual fusions appear as a general benefit for organisms, such as coalescing seaweeds and modular invertebrates, with the capacity to fuse with conspecifics. Using sporelings of the red algae Gracilaria chilensis C. J. Bird, McLachlan et E. C. Oliveira and Mazzaella laminarioides (Bory) Fredericq, we measured the growth patterns of sporelings built with different numbers of spores, and the magnitude and persistence of the size increments gained by fusions. Then we studied three morphological processes that could help explain the observed growth patterns. Results indicate that in these algae, coalescence is followed by immediate increase in total size of the coalesced individual and that the increment is proportional to the number of individuals fusing. However, the size increments in sporelings of both species do not last >60 d. Increasing reductions of marginal meristematic cells and increasing abundance of necrotic cells in sporelings built with increasing numbers of initial spores are partial explanations for the above growth patterns. Since sporelings formed by many spores differentiate erect axes earlier and in larger quantities than sporelings formed by one or only a few spores, differentiation, emergence, and growth of erect axes appear as a more likely explanation for the slow radial growth of the multisporic sporelings. Erect axis differentiation involves significant morphological and physiological changes and a shift from radial to axial growth. It is concluded that the growth pattern exhibited by these macroalgae after fusion differs from equivalent processes described for other organisms with the capacity to fuse, such as modular invertebrates. [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 76JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003D Pareyson The X-linked form of Charcot-Marie-Tooth disease (CMTX) is associated with mutations in the Connexin 32 gene (Cx32) and is the second most common CMT subtype after CMT1A, in which the 17p11.2 duplication is the underlying molecular defect. CMTX is characterized by no male-to-male transmission, intermediate motor conduction velocities (MCV), and more severe disease in males. In our series of CMT patients, we found 9 different Cx32 mutations in 11 families. Overall there were 26 patients, 13 males and 13 females, aged 11,76 yrs. Age at onset ranged considerably (1,60 yrs), but symptoms began earlier in males (mean 15.4 yrs, 77% within age 20) than in females (mean 25 yrs). All patients were autonomous, but disease severity was greater in males, while 4 female carriers were asymptomatic. Pain and tremor were frequent complaints. Two patients had Babinski sign and one had rest tremor. Nerve conduction studies were performed in 23 patients (13 males, 10 females). Upper limb motor conduction velocities (MCV) ranged between 25 and 57 m/s, and were slower in males (25,48 m/s) than in females (34,57 m/s). MCV were in the upper range of CMT1 (25,38 m/s) in 10/13 males but only in 3/10 females. In some cases, nerve conduction slowing was non-uniform within single nerves, and one female patient had a previous diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy. There was considerable asymmetry of involvement between different nerves. The median nerve was often more severely affected than the ulnar nerve, and not only in females, as previously reported, but also in males. Therefore, it appears unlikely that this asymmetry is accounted for by a Lyonization phenomenon. Subclinical abnormalities of central nervous system as revealed by multimodal evoked potential studies were found in 8/10 patients. Expression of Cx32 in the brain is the likely explanation of this finding that confirms previous non-systematic observations. We found seven missense and two nonsense mutations (one novel mutation). Two families presented distinct mutations at the same codon (Arg164), while the Arg22Stop and Arg220Stop mutations were each found in two unrelated cases. Partially supported by a grant from the Italian Ministry of Health to F.T and D.P. (Progetto Ricerca Finalizzata ICS 030.3/RF00.174). [source] Is there limiting similarity in the phenology of fleshy fruits?JOURNAL OF VEGETATION SCIENCE, Issue 6 2005K.C. Burns Abstract Question: Is there evidence for limiting similarity in the timing of fruit production by a bird-dispersed plant community? Is the rate of fruit removal in each plant species inversely related to fruit availability in other species? Can simple measurements of fruit phenologies (i.e. temporal changes in fruit availability) obscure important fruit attributes that influence their removal by birds? Location: Vancouver Island, British Columbia, Canada. Methods: Periods of fruit availability were measured in ten woody angiosperm species for two years. In the second year, the fate of individual fruits was quantified to disentangle dates of fruit maturation, removal and mortality from measurements of availability. Results: Null model analyses of fruit availability distributions showed no evidence for limiting similarity. However, fruit removal rates of most plant species were correlated with their relative abundance in the community, indicating fruits were removed more rapidly when other fruits were less abundant. Species with similar periods of fruit availability often had different dates of fruit maturation, rates of fruit removal and fruit persistence times, indicating fruit availability measurements can obscure important bird-fruit interactions. Conclusions: Competition for dispersers appears to occur. However, it has not resulted in limiting similarity in fruit availability distributions. A likely explanation for this discrepancy is that fruit availability distributions often confound several important fruit attributes that can independently influence fruit removal by birds. [source] Flies in the ointment: a morphological and molecular comparison of Lucilia cuprina and Lucilia sericata (Diptera: Calliphoridae) in South AfricaMEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2009R. TOURLE Abstract Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long-held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina -like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation. [source] The narrow-line quasar NAB 0205 + 024 observed with XMM,NewtonMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2004L. C. Gallo ABSTRACT The XMM,Newton observation of the narrow-line quasar NAB 0205+024 reveals three striking differences since it was last observed in X-rays with ASCA. First, the 2,10 keV power law is notably steeper. Secondly, a hard X-ray flare is detected, very similar to that seen in I Zw 1. Thirdly, a strong and broad emission feature is detected with the bulk of its emission redward of 6.4 keV, and extending down to ,5 keV in the rest frame. The most likely explanation for the broad feature is neutral iron emission emitted from a narrow annulus of an accretion disc close to the black hole. The hard X-ray flare could be the mechanism that illuminates this region of the disc, allowing for the emission line to be detected. The combination of effects can be understood in terms of the ,thunder-cloud' model proposed by Merloni & Fabian. [source] Changes in convective properties over the solar cycle: effect on p-mode damping ratesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001G. Houdek Measurements of both solar irradiance and p-mode oscillation frequencies indicate that the structure of the Sun changes with the solar cycle. Balmforth, Gough & Merryfield investigated the effect of symmetrical thermal disturbances on the solar structure and the resulting pulsation frequency changes. They concluded that thermal perturbations alone cannot account for the variations in both irradiance and p-mode frequencies, and that the presence of a magnetic field affecting acoustical propagation is the most likely explanation of the frequency change, in the manner suggested earlier by Gough & Thompson and by Goldreich et al. Numerical simulations of Boussinesq convection in a magnetic field have shown that at high Rayleigh number the magnetic field can modify the preferred horizontal length scale of the convective flow. Here, we investigate the effect of changing the horizontal length scale of convective eddies on the linewidths of the acoustic resonant mode peaks observed in helioseismic power spectra. The turbulent fluxes in these model computations are obtained from a time-dependent, non-local generalization of the mixing-length formalism. The modelled variations are compared with p-mode linewidth changes revealed by the analysis of helioseismic data collected by the Birmingham Solar-Oscillations Network (BiSON); these low-degree (low- l) observations cover the complete falling phase of solar activity cycle 22. The results are also discussed in the light of observations of solar-cycle variations of the horizontal size of granules and with results from 2D simulations by Steffen of convective granules. [source] Differentiation of hydatid cyst from cysticercus cyst by proton MR spectroscopyNMR IN BIOMEDICINE, Issue 5 2002Monika Garg Abstract The metabolite patterns obtained by ex vivo proton MR spectroscopy of fluid from different locations of hydatid cysts of sheep and humans (n,=,16) and cysticercus cysts of swine and humans (n,=,25) were compared with an objective of differentiating the two parasites on the basis of their metabolite pattern. The spectra from hydatid fluid differed from cysticercus cyst by the absence of creatine in the former. When the hydatid cyst was fertile, malate and/or fumarate was also observed, which was absent in cysticercus cyst. The most likely explanation for the presence of creatine only in the cysticercus fluid is its active diffusion from the surrounding host tissue along with a contribution from the musculature present in the bladder wall of the cyst. Copyright © 2002 John Wiley & Sons, Ltd. [source] Cryogenic sediment-filled wedges, northern Delaware, USAPERMAFROST AND PERIGLACIAL PROCESSES, Issue 4 2004Mary D. Lemcke Abstract Wedge-like sedimentary structures at two sites in northern Delaware USA are located at the erosional surface of, and extend into, channel deposits of the fluvial, mid-Pleistocene Columbia Formation. The wedges are 0.25,0.60,m wide at the top, 1.0,1.5,m in vertical extent, contain moderate to poorly sorted, and vertically-stratified sediment, and are overlain unconformably by a layer of wind-blown silt. Several hypotheses for the formation and infill of the wedges were evaluated using detailed physical, stratigraphic, and sedimentological information. The most likely explanation for the features is that they are relict cryogenic structures formed by thermal-contraction cracking in permafrost, and filled with wind-blown sediments derived from the Columbia Formation. The wedges are believed to have formed in the tundra environment that existed in northern Delaware, south of the Laurentide Ice Sheet, during the coldest parts of the Wisconsinan glaciation. Copyright © 2004 John Wiley & Sons, Ltd. [source] Short- and long-term consequences of early parental loss in the historical population of the Krummhörn (18th and 19th century)AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2009Kai P. Willführ The impact of the early loss of one's father or one's mother on the survival and age at death of children was investigated on the basis of a historical reconstitution of families from the Krummhörn (East Frisia/Ostfriesland; Germany) with the aid of Kaplan-Meier plots and the Cox regression. In our analyses, we took into account the changed situation of the family after the death of a parent by incorporating the surviving spouse's remarriage or relationships with stepparents. We find that the impact on survival of the children was sex-specific and also depended on whether and at what point in time during childhood their father or mother had died. As expected, children's immediate survival was strongly affected by maternal loss. A few results can be construed as survival diminishing long-term consequences of the early loss of a parent. Daughters who lost their fathers before their first birthday proved to have increased mortality over a longer period of their youth. The age at death of daughters was also lowered if they had to live with a step-mother during early childhood. To interpret these results, three hypotheses, including an (intrinsic) trade-off, compensation and a selection scenario, were tested. Other approaches, which are based, for example, on the extrinsic trade-off between mating effort and parental investment of the surviving parent, also appear to be suitable as an explanation for the long-term consequences, which eventually draws the conclusion that the compensation scenario is the most likely explanation for the consequences of early parental loss. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||