The Lx-T Relation and Intracluster Gas Fractions of X-ray Clusters

We re-examine the X-ray luminosity-temperature relation using a nearly homogeneous data set of 24 clusters selected for statistically accurate temperature measurements and absence of strong cooling flows. The data exhibit a remarkably tight power-law relation between bolometric luminosity and temperature with a slope 2.88 \pm 0.15. With reasonable assumptions regarding cluster structure, we infer an upper limit on fractional variations in the intracluster gas fraction <(\delta\fgas/\fgas)^2)^1/2 \le 15%. Imaging data from the literature are employed to determine absolute values of fgas within spheres encompassing density contrast 500 and 200 with respect to the critical density. Comparing binding mass estimates based on the virial theorem (VT) and the hydrostatic, betamodel (BM), we find a temperature-dependent discrepancy in fgas between the two methods caused by sytematic variation of the outer slope parameter beta with temperature. There is evidence that cool clusters have a lower mean gas fraction that hot clusters, but it is not possible to assess the statistical significance of this effect in the present dataset. The temperature dependance of the ICM density structure, coupled with the increase of the gas fraction with T in the VT aproach, explains the steepening of the Lx-T relation. The small variation about the mean gas fraction within this majority sub-population of clusters presents an important constraint for theories of galaxy formation and supports arguments against an Einstein-deSitter universe based on the population mean gas fraction and primordial nucleosynthesis. The apparent trend of lower gas fractions and more extended atmospheres in low T systems are consistent with expectations of models incorporating the effects of galactic winds on the ICM. ABRIDGEDComment: 11 pages, 4 figures, uses mn.sty and epsf.sty, accepted for publication in MNRAS; minor modifications: discussion added on CF LX (Sec. 3.1);comparison with Allen & Fabian L-T results (Sec.3.1 & Sec.4.4); statistics precised (3.1), discussion clarified (Sec. 2.2,Sec. 4.4); slight mistake in the r-T and M-T relation calibration corrected and thus fgas in Fig.3, Fig 4, Tab 2 slightly change

Spatial Disaggregation of Agricultural Production Data

In this paper we develop a dynamic data-consistent way for estimating agricultural land use choices at a disaggregate level (district-level), using more aggregate data (regional-level). The disaggregation procedure requires two steps. The first step consists in specifying and estimating a dynamic model of land use at the regional level. In the second step, we disaggregate outcomes of the aggregate model using maximum entropy (ME). The ME disaggregation procedure is applied to a sample of California data. The sample includes 6 districts located in Central Valley and 8 possible crops, namely: Alfalfa, Cotton, Field, Grain, Melons, Tomatoes, Vegetables and Subtropical. The disaggregation procedure enables the recovery of land use at the district-level with an out-sample prediction error of 16%. This result shows that the micro behavior, inferred from aggregate data with our disaggregation approach, seems to be consistent with observed behavior.Disaggregation, Bayesian method, Maximum entropy, Land use, Production Economics, C11, C44, Q12,

Characterisation of biodiversity in improved rubber agroforests in West-Kalimantan, Indonesia. Real and Potential uses for spontaneous plants

Since the introduction of rubber at the turn of the 20th century smallholders have developed an original complex agroforestry system called jungle rubber in which non selected young rubber trees (seedlings) are managed extensively alongside secondary forest re-growth. The issue of improving smallholder rubber productivity at affordable capital investments and levels of inputs while maintaining the environmental benefits of jungle rubber has been addressed by the Smallholder Rubber Agroforestry Project (SRAP: a joint project run by ICRAF, GAPKINDO and CIRAD). In 1995-1996, 27 trials (with a total of 100 plots) were set up in three provinces in Indonesia to assess the possibility of associating clonal rubber with agroforestry practices under smallholder conditions (Penot, 1997). Two RAS types were selected for this study: RAS n° 1 and n° 3. RAS n° 1 is basically improved jungle rubber using clonal planting material (see a description of RAS types in annexe 1). The rubber trees are in competition with spontaneous vegetation in the inter-row but results show that there are no negative consequences for rubber growth during the immature period. RAS n° 3 was designed for areas infested by Imperata cylindrica, with the establishment of shrubby leguminous cover crops and fast-growing tree species in the inter-rows with the aim of shading out weeds. The other type, RAS n° 2, is based on intercropping clonal rubber with various annual and perennial crops, including fruit and timber trees (Penot et al, 1994). In all cases, RAS have a planting density of 550 clonal rubber trees/ha and a variable number of associated fruit, timber or fast growing shade trees (from 92 to 256/ha). In addition to the RAS experimental plots, “RAS sendiri” (or “endogenous RAS”) are rubber agroforests improved by farmers without outside assistance. The district of Sanggau in the province of West Kalimantan was identified by SRAP as representative of traditional jungle-rubber-based local farming systems that have developed over the last 90 years. The district of Sanggau is located in the central area of the Kapuas river basin, between 1° N and 0°6' S and 09°8' W and 11°33' E. The district covers 18 302 km2, i.e. 13 % of the province. The trial plots described in this study are located in the villages of Embaong, Engkayu, Kopar, and Trimulia (the last being in the transmigration area). Most soils in the province of West-Kalimantan are acrisoils associated with ferralitic soils. Such soils have relatively good physical characteristics but poor chemical value and become acid. Rubber is widely grown in this area as it can grow in poor soils. The landscape is dominated by logged-over forest, secondary forest and a mosaic of jungle rubber and fallow with secondary forest re-growth. Large scale logging activities took place from 1950s to the 1980s at the expense of primary forest. At present, forested areas are located in hilly or remote areas and are very limited in extent. Oil palm and Acacia mangium plantations developed exponentially in the 1990s increasing the conversion of degraded forest areas into Estates that cultivate perennial crops. The main objective of this study is to assess existing plant biodiversity in RAS systems compared to that of jungle rubber. The second objective is to review the current uses of certain plants and their market potential.

Probing the dark matter profile of hot clusters and the M-T relation with XMM-Newton

We present results based on XMM-Newton observations of a small sample of hot galaxy clusters. Making a full use of XMM-Newton's spectro-imaging capabilities, we have extracted the radial temperature profile and gas density profile, and with this information, calculated the total mass profile of each cluster (under the assumption of hydrostatic equilibrium and spherical symmetry). Comparing the individual scaled total mass profiles, we have probed the Universality of rich cluster mass profiles over a wide range of radii (from 0.01 to 0.7 the virial radius). We have also tested the shape of cluster mass profiles by comparing with the predicted profiles from numerical simulations of hierarchical structure formation. We also derived the local mass-temperature (M-T) scaling relation over a range of temperature going from 4 to 9 keV, that we compare with theoretical predictions.Comment: 7 pages, 2 figures, Advances in Space Research in press (proceedings of the COSPAR 2004 Assembly, Paris

The structural and scaling properties of nearby galaxy clusters: I - The universal mass profile

We present the integrated mass profiles for a sample of ten nearby (z<=0.15), relaxed galaxy clusters, covering a temperature range of [2-9]keV, observed with XMM-Newton. The mass profiles were derived from the observed gas density and temperature profiles under the hypothesis of spherical symmetry and hydrostatic equilibrium. All ten mass profiles are well described by an NFW-type profile over the radial range from 0.01 to 0.5 R_200, where R_200 is the radius corresponding to a density contrast of 200 with respect to the critical density at the cluster redshift. A King model is inconsistent with these data. The derived concentration parameters and total masses are in the range c_200=4-6 and M_200=1.2 10^14-1.2 10^15 Msol, respectively. Our qualitative and quantitative study of the mass profile shape shows, for the first time, direct and clear observational evidence for the universality of the total mass distribution in clusters. The mass profiles scaled in units of R_200 and M_200 nearly coincide, with a dispersion of less than 15% at 0.1 R_200. The c_200--M_200 relation is consistent with the predictions of numerical simulations for a LCDM cosmology, taking into account the measurement errors and expected intrinsic scatter. Our results provide further strong evidence in favour of the Cold Dark Matter cosmological scenario and show that the dark matter collapse is well understood at least down to the cluster scale.Comment: 8 pages, 5 figures. Accepted for publication in A&

Characterization of laser-produced fast electron source for integrated simulation of fast ignition

Relativistic electron currents (∼ 10 kA µm−2) are produced by focusing an intense laser beam (I ≥ 1019W cm−2) on a solid target. Based on this mechanism, an original inertial confinement fusion scheme has been proposed which consists in heating the compressed deuterium-tritium core with a laser-produced electron beam. Experimentally the fast electron source is not well characterized and simulations of both electron generation and transport remain a difficult task. Generally, transport codes are used with a simplified fast electron source as initial condition. The fast electron spectrum is assumed to be exponential with an adjustable temperature, and the divergence is characterized by a dispersion angle. To verify these assumptions, we have performed a characterization of the laser-driven fast electron source by means of PIC simulations [1] in the cases of a planar foil and a double cone

Prospective randomized study comparing quality of life after shoudice or mesh plug repair for inguinal hernia: short-term results

Postoperative pain is a major obstacle in hernia repair surgery, and the choice of clinically efficacious surgical technique should also result in the least postoperative pain and patients\u27 quality of life (QoL). The aim of this prospective randomized study was to compare two surgical techniques for open inguinal hernia repair by assessing the patients\u27 QoL. Men (18-to-75 years old) with primary unilateral inguinal hernia underwent Mesh Plug (MP; n = 156; Bard (PerFix Plug, CR Bard Inc, Murray Hill, NJ) and Shouldice (S; n = 144) techniques. We evaluated: 1) Intensity of postoperative pain (visual analog scale [VAS]) and 2) quality of life (QoL; Medical Outcomes Study Short-Form 36 [SF-36]). Patients undergoing MP had significantly lower VAS scores on postoperative days (POD) 1 (22.1 vs 27.4, p =.003) and 2 (13.2 vs 21.4, p &lt;.0001) compared to those in the S group. The QoL was also improved in patients undergoing MP on PODs 8 and 45. Total duration of operation, length of hospital stay, and cessation of normal activities were significantly shorter in the MP group. Compared to the S technique, the MP technique results in significantly less postoperative pain and improved QoL

Registering and uploading datasets in the generation CP central registry

Poster presented at Generation Challenge Programme 2009 Annual Research Meeting. Bamako (Mali), 20-23 Sep 200

The emission of Cygnus X-1: observations with INTEGRAL SPI from 20 keV to 2 MeV

We report on Cyg X-1 observations performed by the SPI telescope onboard the INTEGRAL mission and distributed over more than 6 years. We investigate the variability of the intensity and spectral shape of this peculiar source in the hard X-rays domain, and more particularly up to the MeV region. We first study the total averaged spectrum which presents the best signal to noise ratio (4 Ms of data). Then, we refine our results by building mean spectra by periods and gathering those of similar hardness. Several spectral shapes are observed with important changes in the curvature between 20 and 200 keV, even at the same luminosity level. In all cases, the emission decreases sharply above 700 keV, with flux values above 1 MeV (or upper limits) well below the recently reported polarised flux (Laurent et al. 2011), while compatible with the MeV emission detected some years ago by CGRO/COMPTEL (McConnell et al., 2002). Finally, we take advantage of the spectroscopic capability of the instrument to seek for spectral features in the 500 keV region with negative results for any significant annihilation emission on 2 ks and days timescales, as well as in the total dataset.Comment: 14 pages, 10 figures, accepted for publication in Ap