322 research outputs found
A NEW DICTYOPYGID FROM THE CAVE SANDSTONE OF LESOTHO, SOUTHERN AFRICA
The Lower Triassic of South Africa has
yielded an array of early dictyopygids (Brough,
1931, 1936) yet none of those advanced dictyopygids
so characteristic of the Upper Triassic of
North America (Schaeffer, 1967) has so far been
recorded from the African continent. The geographical
distribution of the dictyopygids appears
to be a discontinuous one with the Lower Triassic
forms coming mainly from South Africa, the
Middle Triassic ones from Australia and the Upper
Triassic forms from North America. It is thus
surprising to find a seemingly advanced dictyopygid
in the rather unfossiliferous Cave Sandstone of
Lesotho
Mises en défens et plantations : étude synchronique de deux techniques de restauration pour améliorer les communautés végétales et les propriétés du sol dans des steppes arides dégradées (Algérie)
Steppes of arid Mediterranean zones are deeply threatened by desertification. To stop or
alleviate ecological and economic problems associated with this desertification, management actions have been
implemented since the last three decades. The struggle against desertification has become a national priority in
some of these countries. In Algeria, several management techniques have been used to cope with desertification.
This study aims to investigate the effect of two management techniques on vegetation, soil properties and
pastoral value after four years of implementation. The two techniques were grazing exclosure which was widely
set up in degraded steppes and plantations (consisting in plantation and grazing exclosure) in deeply degraded
ones. 49 phytoecological and soil samples have been studied. Results showed that plant diversity, composition,
vegetation cover and pastoral value were significantly higher in protected areas. Management techniques also
affected soil surface elements (percentage of sand, coarse soil elements, bare silty crust, and bare ground),
organic matter and soil nitrogen content. We also demonstrated that important differences between both techniques
remain: plantation technique on heavily degraded soil results in a higher pastoral value of plant communities
whereas grazing exclosure technique on lesser degraded soil favours plant diversityLe processus de désertification menace depuis de nombreuses années les milieux steppiques arides du bassin méditerranéen. Afin d'arrêter ou atténuer les problèmes écologiques et économiques associés à cette désertification, des
actions de gestion ont été mises en œuvre depuis les trois dernières décennies. Cette lutte est devenue pour certains pays une priorité nationale. En Algérie, plusieurs techniques de gestion visant à limiter le surpâturage ont été utilisées parmi lesquelles la plantation d'Atriplex canescens
provenant d'Amérique centrale et la mise en défens de larges surfaces. Cette étude synchronique compare l'impact de ces deux pratiques de gestion après quatre ans de mise en œuvre sur la flore, la valeur fourragère et plusieurs paramètres édaphiques. Les 49 relevés phytoécologiques effectués
montrent des modifications de la composition floristique, ainsi que des augmentations de la diversité, du recouvrement de végétation et de la valeur pastorale avec la protection des parcelles. L'ordination des résultats sur un plan factoriel permet de caractériser les trajectoires des
différentes formations en fonction du mode de gestion qui leur est appliqué. Ces résultats mettent en évidence des groupements à richesse modérée et haute valeur pastorale dans les plantations, alors que les mises en défens conduisent à des formations à richesse élevée mais à valeur
pastorale plus faible. Les paramètres édaphiques mesurés sont également affectés par la gestion: diminution de la fraction sableuse, des éléments grossiers, de la pellicule de glaçage, du sol nu et augmentation de la teneur en matière organique et azote total. Les conséquences de ces deux
modes de gestion en termes de restauration et de réhabilitation écologiques sont discutées
The population biology of the living coelacanth studied over 21 years
Between 1986 and 2009 nine submersible and
remote-operated vehicle expeditions were carried out to
study the population biology of the coelacanth Latimeria
chalumnae in the Comoro Islands, located in the western
Indian Ocean. Latimeria live in large overlapping home
ranges that can be occupied for as long as 21 years. Most
individuals are confined to relatively small home ranges,
resting in the same caves during the day. One hundred and
forty five coelacanths are individually known, and we
estimate the total population size of Grande Comore as
approximately 300–400 adult individuals. The local population
inhabiting a census area along an 8-km section of
coastline remained stable for at least 18 years. Using
LASER-assisted observations, we recorded length frequencies
between 100 and 200 cm total length and did not
encounter smaller-bodied individuals (\100 cm total
length). It appears that coelacanth recruitment in the
observation areas occur mainly by immigrating adults. We
estimate that the mean numbers of deaths and newcomers
are 3–4 individuals per year, suggesting that longevity may
exceed 100 years. The domestic fishery represents a threat
to the long-term survival of coelacanths in the study area.
Recent changes in the local fishery include a decrease in
the abundance of the un-motorized canoes associated with
exploitation of coelacanths and an increase in motorized
canoes. Exploitation rates have fallen in recent years, and
by 2000, had fallen to lowest ever reported. Finally, future
fishery developments are discussed
Central GIP signaling stimulates peripheral GIP release and promotes insulin and pancreatic polypeptide secretion in nonhuman primates
Glucose-dependent insulinotropic polypeptide (GIP) has important actions on whole body metabolic function. GIP and its receptor are also present in the central nervous system and have been linked to neurotrophic actions. Metabolic effects of central nervous system GIP signaling have not been reported. We investigated whether centrally administered GIP could increase peripheral plasma GIP concentrations and influence the metabolic response to a mixed macronutrient meal in nonhuman primates. An infusion and sampling system was developed to enable continuous intracerebroventricular (ICV) infusions with serial venous sampling in conscious nonhuman primates. Male baboons (Papio sp.) that were healthy and had normal body weights (28.9 ± 2.1 kg) were studied (n = 3). Animals were randomized to receive continuous ICV infusions of GIP (20 pmol·kg−1·h−1) or vehicle before and over the course of a 300-min mixed meal test (15 kcal/kg, 1.5g glucose/kg) on two occasions. A significant increase in plasma GIP concentration was observed under ICV GIP infusion (66.5 ± 8.0 vs. 680.6 ± 412.8 pg/ml, P = 0.04) before administration of the mixed meal. Increases in postprandial, but not fasted, insulin (P = 0.01) and pancreatic polypeptide (P = 0.04) were also observed under ICV GIP. Effects of ICV GIP on fasted or postprandial glucagon, glucose, triglyceride, and free fatty acids were not observed. Our data demonstrate that central GIP signaling can promote increased plasma GIP concentrations independent of nutrient stimulation and increase insulin and pancreatic polypeptide responses to a mixed meal
Relationships of †Codoichthys carnavalii Santos, 1994 (Teleostei, Clupeomorpha, †Ellimmichthyiformes) from the Late Aptian of São Luís-Grajaú Basin, NE Brazil
Assesment of resolution and intercenter reproducibility of results of genotyping staphyloccoccus aureus by pulsed-field gel electrophoresis of SMA1 macrorestriction fragments: a multicenter study
Assesment of resolution and intercenter reproducibility of results of genotyping staphyloccoccus aureus by pulsed-field gel electrophoresis of SMA1 macrorestriction fragments: a multicenter study
The cumulative risk of lung cancer among current, ex- and never-smokers in European men
Recent analyses based on UK data indicate that people who stop smoking, even well into middle age, avoid most of their subsequent risk of lung cancer. We investigated whether similar absolute risks of lung cancer in men are found in other European countries with different smoking patterns and at different stages of their lung cancer epidemic. Using data for men from a multicentre case-control study of lung cancer in the UK, Germany, Italy and Sweden, and including 6523 lung cancer cases and 9468 controls, we combined odds ratio estimates with estimates of national lung cancer incidence rates to calculate the cumulative risk of lung cancer among men by age 75. Lung cancer cumulative risks by age 75 among continuing smokers were similar for the UK, Germany and Italy at 15.7, 14.3 and 13.8% respectively, whereas the cumulative risk among Swedish male smokers was 6.6%. The proportion of the risk of lung cancer avoided by quitting smoking before the age of 40 was comparable between the four countries, at 80% in Italy and 91% in the UK, Germany and Sweden. Similarly, the proportion of the excess risk avoided by quitting before the age of 50 ranged from 57% in Italy to 69% in Germany. Our results support the important conclusion that for long-term smokers, giving up smoking in middle age avoids most of the subsequent risk of lung cancer, and that lung cancer mortality in European men over the next three decades will be determined by the extent to which current smokers can successfully quit smoking
Smokers making a quit attempt using e-cigarettes with or without nicotine or prescription nicotine replacement therapy : impact on cardiovascular function (ISME-NRT) - a study protocol
Background: The estimated number of cigarette smokers in the world is 1.3 billion, expected to rise to 1.7
billion by 2025, with 10 million smokers living in the U.K. Smoking is the leading, preventable death-cause
worldwide, being responsible for almost 650,000 deaths in the E.U. annually. A combination of pharmacological
interventions, including nicotine replacement therapy, bupropion and varenicline, and behavioural support is the most effective approach to smoking cessation. However, even the best methods have high relapse rates of approximately
75% within 6 months. Electronic (or “e-“) cigarettes use battery power to disperse a solution that usually contains
propylene glycol or glycerine, water, flavouring and nicotine. E-cigarettes have become the most popular smoking
cessation aid in England, however, information on their effects on cardiovascular function is limited and contradictory.
As e-cigarettes are not solely nicotine-based products, existing research exploring the effects of nicotine on
the cardio-vasculature provides only limited information, while their extensive uptake urges the need of
evidence to inform the general public, smokers and policy-makers.
Methods: This is a pragmatic, 3-group, randomised, assessor-blinded, single-centre trial exploring the cardiovascular
physiological effects of the use of e-cigarettes (nicotine-free and nicotine-inclusive, assessed separately) combined with behavioural support as a smoking cessation method in comparison to the combination of NRT and behavioural
support. The primary outcome will be macro-vascular function, determined by a Flow Mediated Dilatation ultrasound assessment, 6 months following participants’ “quit date”.
Discussion: Participants will be assessed at baseline, 3 days following their self-determined “quit date”, at intervention end (3 months) and 6 months following their “quite date”. Findings are expected to give an indication of the cardiovascular effects of e-cigarettes both in the short- and in the medium-term period, informing the general public,policy holders and researchers, helping to define the future role of e-cigarettes as a smoking cessation aid
Assessment of resolution and intercenter reproducibility of results of genotyping Staphylococcus aureus by pulsed-field gel electrophoresis of SmaI macrorestriction fragments: a multicenter study
Twenty well-characterized isolates of methicillin-resistant Staphylococcus
aureus were used to study the optimal resolution and interlaboratory
reproducibility of pulsed-field gel electrophoresis (PFGE) of DNA
macrorestriction fragments. Five identical isolates (one PFGE type), 5
isolates that produced related PFGE subtypes, and 10 isolates with unique
PFGE patterns were analyzed blindly in 12 different laboratories by
in-house protocols. In several laboratories a standardized PFGE protocol
with a commercial kit was applied successfully as well. Eight of the
centers correctly identified the genetic homogeneity of the identical
isolates by both the in-house and standard protocols. Four of 12
laboratories failed to produce interpretable data by the standardized
protocol, due to technical problems (primarily plug preparation). With the
five rel
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