273 research outputs found
Egg production in the euryhaline tilapia, Sarotherodon melanotheron heudelotii, experimentally maintained in fresh, sea and hypersaline waters
Through the experiments presented here we wanted to test whether egg production of the black-chinned tilapia Sarotherodon melanotheron heudelotii under experimental conditions varies as a function of ambient salinity (fresh waters vs. sea waters vs. hypersaline waters, 0, 35 and 70, respectively) and whether these responses differ between fish acclimated within a few weeks from fresh water to saline and hypersaline environments (experiments E1 and E2, monitoring over 10 and 18 weeks), and individuals born and raised all life long at the experimental salinities (E3, monitoring over 18 weeks). In total, 233 spawns were collected. In each of the three experiments, the reproductive investment (gram of egg per gram of female over 2 weeks) did not differ between salinities of 0 and 35, whereas it was 2-3 times lower at 70 than at 0-35, because of lower spawning frequency (E1-E3), smaller clutch size (E1) and lower spawn mass (E1-E3). Finally, fish acclimated to salinity from fresh water over a few weeks and those maintained at a particular salinity all life long showed similar reproductive traits, thereby emphasizing the remarkable physiological plasticity of this species
Folk taxonomy and traditional management of cassava (Manihot esculenta Crantz) diversity in southern and central Benin
Cassava (Manihot esculenta Crantz) is an important food security crop for poor rural communities, particularly in Africa. At household level, cassava landraces used for cultivation are mainly selected based on farmers' interests, leading to very particular diversity evolution over generations. The structure, composition and factors influencing cassava diversity at that level is not well monitored and under documented. This study aimed at capturing and analyzing local knowledge on cassava genetic diversity and the key parameters affecting it in Benin, for better and sustainable local cassava genetic resources management. The methodological approach was based on field visits, interview using questionnaire and group discussion with farmers. Data were collected from one hundred and ninety eight (198) respondents and analyzed using descriptive statistics. The majority (82%) of the respondents were male, generally 20 to 80 years old. Positive correlation was found between cassava diversity maintained per household with cultivated area and household size (R2 = 0.162). Farmers used mainly stem and leaves characteristics to identify cassava varieties. Plant materials for next season were mostly selected according to the disease (mainly plant free of viral infection) status, size of the stem and number of nodes. The study revealed existence of a high diversity of cassava at the household level. However, various factors constrained cassava production and threats on cassava diversity were observed. Establishment of community field genebank, introduction of new varieties were some of the on-farm conservation strategies proposed by cassava farmers
ADAMTS9-regulated pericellular matrix dynamics governs focal adhesion-dependent smooth muscle differentiation
Focal adhesions anchor cells to extracellular matrix (ECM) and direct assembly of a pre-stressed actin cytoskeleton. They act as a cellular sensor and regulator, linking ECM to the nucleus. Here, we identify proteolytic turnover of the anti-adhesive proteoglycan versican as a requirement for maintenance of smooth muscle cell (SMC) focal adhesions. Using conditional deletion in mice, we show that ADAMTS9, a secreted metalloprotease, is required for myometrial activation during late gestation and for parturition. Through knockdown of ADAMTS9 in uterine SMC, and manipulation of pericellular versican via knockdown or proteolysis, we demonstrate that regulated pericellular matrix dynamics is essential for focal adhesion maintenance. By influencing focal adhesion formation, pericellular versican acts upstream of cytoskeletal assembly and SMC differentiation. Thus, pericellular versican proteolysis by ADAMTS9 balances pro- and anti-adhesive forces to maintain an SMC phenotype, providing a concrete example of the dynamic reciprocity of cells and their ECM
Funiculars anomalies during childbirth: about 562 cases collected in Pikine National Hospital
Background: Establish an epidemiological description of the different types of umbilical cord anomalies in our reference structure and to assess their impact on the prognosis of childbirth.Methods: We conducted a descriptive study, cross over a period of one year in Obstetrics and Gynecology Service Level III of Pikine Hospital. We included all women in labor have reached the term less than 28 weeks gestation and delivering a newborn with umbilical cord abnormality diagnosed during labor or during the expulsion.Results: During this period, we compiled 562 anomalies of the umbilical cord, which gave a frequency of 23.8%. Length discrepancies were far the most frequent (67.4%). Only the prolapsed cord was an independent risk factor for cesarean section (p = 0.036). The rate of episiotomy and tear was significantly higher in case of brevity (primitive or induced) cord (p = 0.042). Apgar score â€7 was significantly related to the presence of brevity (p = 0.000), excessive length (p = 0.048) or cord prolapse (p = 0.037).Conclusions: This study has allowed us to see that the funicular abnormalities impede the smooth running of childbirth. Their occurrence is facilitated by the excess amniotic fluid, prematurity and low birth weight. Their research during prenatal ultrasounds should be systematic
Prévalence de la démence dans une population de personnes ùgées sénégalaises
Description Avec le vieillissement de la population, survient la dĂ©mence dans la population de personnes ĂągĂ©es. Objectif. Lâobjectif de cette Ă©tude Ă©tait dâestimer la prĂ©valence de cette affection dans une population de personnes ĂągĂ©es sĂ©nĂ©galaises. MĂ©thodes Par une Ă©tude transversale qui sâest dĂ©roulĂ©e du 01 mars 2004 au 31 dĂ©cembre 2005, des personnes ĂągĂ©es de 55 ans et plus venant consulter pour un problĂšme de santĂ© au Centre MĂ©dico-Social et Universitaire de lâIPRES (SĂ©nĂ©gal) ont Ă©tĂ© Ă©valuĂ©es sur le plan clinique et neuropsychologique. Des donnĂ©es sur les caractĂ©ristiques sociodĂ©mographiques, les antĂ©cĂ©dents mĂ©dico-chirurgicaux et familiaux, le mode de vie, le rĂ©seau social ont Ă©tĂ© collectĂ©es Ă lâaide dâun questionnaire structurĂ© avec des rĂ©ponses fermĂ©es. RĂ©sultat La population Ă lâĂ©tude Ă©tait composĂ©e de 872 personnes. Elles avaient un Ăąge moyen de 67,2 ans ± 7,5.Elles Ă©taient de sexe masculin (62,6%), mariĂ©es (79%), non instruites (50,7%). Dans les antĂ©cĂ©dents, lâHTA, le diabĂšte, les affections respiratoires, les affections rhumatismales, la cataracte et les troublesdigestifs Ă©taient les plus frĂ©quents. Le tabagisme et lâalcoolisme Ă©tait faible alors que la marche constituait la principale activitĂ© physique. Les personnes ĂągĂ©es vivaient en famille avec un bon rĂ©seau social.Cinquante huit (58) personnes ont prĂ©sentĂ© une dĂ©mence (6,6%). La prĂ©valence de la maladie variait de maniĂšre significative avec lâĂąge et lâinstruction. Conclusion Ce rĂ©sultat confirme que la prĂ©valence de la dĂ©mence varie en fonction de lâĂąge et de lâinstruction de la personne ĂągĂ©e
On handling urban informality in southern Africa
In this article I reconsider the handling of urban informality by urban planning and management systems in southern Africa. I argue that authorities have a fetish about formality and that this is fuelled by an obsession with urban modernity. I stress that the desired city, largely inspired by Western notions of modernity, has not been and cannot be realized. Using illustrative cases of topâdown interventions, I highlight and interrogate three strategies that authorities have deployed to handle informality in an effort to create or defend the modern city. I suggest that the fetish is built upon a desire for an urban modernity based on a concept of formal order that the authorities believe cannot coexist with the âdisorderâ and spatial âunrulinessâ of informality. I question the authorities' conviction that informality is an abomination that needs to be âconvertedâ, dislocated or annihilated. I conclude that the very configuration of urban governance and socio-economic systems in the region, like the rest of sub-Saharan Africa, renders informality inevitable and its eradication impossible
Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering
We present the first measurements of the \vec{e}p->epg cross section in the
deeply virtual Compton scattering (DVCS) regime and the valence quark region.
The Q^2 dependence (from 1.5 to 2.3 GeV^2) of the helicity-dependent cross
section indicates the twist-2 dominance of DVCS, proving that generalized
parton distributions (GPDs) are accessible to experiment at moderate Q^2. The
helicity-independent cross section is also measured at Q^2=2.3 GeV^2. We
present the first model-independent measurement of linear combinations of GPDs
and GPD integrals up to the twist-3 approximation.Comment: 5 pages, 4 figures, 2 tables. Text shortened for publication.
References added. One figure remove
Deeply Virtual Compton Scattering off the neutron
The present experiment exploits the interference between the Deeply Virtual
Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the
imaginary part of DVCS amplitudes on the neutron and on the deuteron from the
helicity-dependent D cross section measured at =1.9
GeV and =0.36. We extract a linear combination of generalized parton
distributions (GPDs) particularly sensitive to , the least constrained
GPD. A model dependent constraint on the contribution of the up and down quarks
to the nucleon spin is deduced.Comment: Published in Phys. Rev. Let
The E00-110 experiment in Jefferson Lab's Hall A: Deeply Virtual Compton Scattering off the Proton at 6 GeV
We present final results on the photon electroproduction
() cross section in the deeply virtual Compton
scattering (DVCS) regime and the valence quark region from Jefferson Lab
experiment E00-110. Results from an analysis of a subset of these data were
published before, but the analysis has been improved which is described here at
length, together with details on the experimental setup. Furthermore,
additional data have been analyzed resulting in photon electroproduction cross
sections at new kinematic settings, for a total of 588 experimental bins.
Results of the - and -dependences of both the helicity-dependent and
helicity-independent cross sections are discussed. The -dependence
illustrates the dominance of the twist-2 handbag amplitude in the kinematics of
the experiment, as previously noted. Thanks to the excellent accuracy of this
high luminosity experiment, it becomes clear that the unpolarized cross section
shows a significant deviation from the Bethe-Heitler process in our kinematics,
compatible with a large contribution from the leading twist-2 DVCS term to
the photon electroproduction cross section. The necessity to include
higher-twist corrections in order to fully reproduce the shape of the data is
also discussed. The DVCS cross sections in this paper represent the final set
of experimental results from E00-110, superseding the previous publication.Comment: 48 pages, 32 figure
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