I. Collisional evolution and reddening of asteroid surfaces: The problem of conflicting timescales and the role of size-dependent effects

Space weathering is the generic term used for processes that modify the optical properties of surfaces of atmosphereless rocky bodies under exposure to the space environment. The general agreement about the relevance of the effects of space weathering on the spectral properties of S-complex asteroids fails when some basic quantitative estimates are attempted. In particular, there is severe disagreement regarding the typical timescales for significant spectral reddening to occur, ranging from 1 Myr to 1 Gyr. Generally speaking, the spectral reddening of an individual object can be considered as the sum of three terms, one (which is relevant for statistical analyses) depending on the exposure of the object to space weathering during its lifetime, a second one due to the original surface composition, and a third one (a "noise" term) due to the combination of poorly constrained effects (e.g., structure and texture of the surface). The surface of an asteroid is usually covered by regolith, and its presence and properties presumably play a critical role in the weathering processes. In this paper we discuss the role played by collisional evolution in affecting the spectral properties of asteroids and refreshing the surfaces due to the formation of ejecta, and the necessity of a simultaneous modeling of collisions and weathering processes. We introduce a new idea, based on the possibility of a sort of saturation of the refreshing process whenever a massive reaccumulation of the impact ejecta takes place. In this case, a dependence of the overall reddening on the asteroid size should naturally come out. We show that this conclusion is indeed supported by available main belt asteroid spectroscopic data.Comment: Accepted by MNRA

Heating of near-Earth objects and meteoroids due to close approaches to the Sun

It is known that near-Earth objects (NEOs) during their orbital evolution may often undergo close approaches to the Sun. Indeed it is estimated that up to ~70% of them end their orbital evolution colliding with the Sun. Starting from the present orbital properties, it is possible to compute the most likely past evolution for every NEO, and to trace its distance from the Sun. We find that a large fraction of the population may have experienced in the past frequent close approaches, and thus, as a consequence, a considerable Sun-driven heating, not trivially correlated to the present orbits. The detailed dynamical behaviour, the rotational and the thermal properties of NEOs determine the exact amount of the resulting heating due to the Sun. In the present paper we discuss the general features of the process, providing estimates of the surface temperature reached by NEOs during their evolution. Moreover, we investigate the effects of this process on meteor-size bodies, analyzing possible differences with the NEO population. We also discuss some possible effects of the heating which can be observed through remote sensing by ground-based surveys or space missions.Comment: 8 pages, 5 figures, accepted by MNRA

Physical Investigation of the Potentially Hazardous Asteroid (144898) 2004 VD17

In this paper we present the observational campaign carried out at ESO NTT and VLT in April and May 2006 to investigate the nature and the structure of the Near Earth Object (144898) 2004 VD17. In spite of a great quantity of dynamical information, according to which it will have a close approach with the Earth in the next century, the physical properties of this asteroid are largely unknown. We performed visible and near--infrared photometry and spectroscopy, as well as polarimetric observations. Polarimetric and spectroscopic data allowed us to classify 2004 VD17 as an E-type asteroid. A good agreement was also found with the spectrum of the aubrite meteorite Mayo Belwa. On the basis of the polarimetric albedo (p_v=0.45) and of photometric data, we estimated a diameter of about 320 m and a rotational period of about 2 hours. The analysis of the results obtained by our complete survey have shown that (144898) 2004 VD17 is a peculiar NEO, since it is close to the breakup limits for fast rotator asteroids, as defined by Pravec and Harris (2000). These results suggest that a more robust structure must be expected, as a fractured monolith or a rubble pile in a "strength regime" (Holsapple 2002).Comment: 32 pages, 7 figure, paper accepted for publication in Icaru

New findings on asteroid spin-vector distributions

Abstract The number of known spin vectors of main belt and near-Earth asteroids is regularly growing, including new objects, and updating the estimates concerning known cases, with the aid of new observations and of improved observational techniques. A reliable statistical analysis of the spin vectors is now possible. In general the poles (both for MB bodies and for NEAs) are not isotropically distributed, as some general theoretical considerations may predict. Main belt asteroids show a lack of poles close to the ecliptic plane. There is a marginally significant excess of prograde spinners in the 100-150 km size range, but interestingly there is not a statistically significant excess in the larger size range. Among NEAs, there is an excess of retrograde rotations. The distributions of longitudes of poles of both groups do not show statistically significant deviations from random. We discuss the possible physical implications of the various resulting pole anisotropies in terms of dynamical-mainly non-gravitational-effects, and point out the importance of new observational campaigns, mainly devoted to compute the poles of small bodies and of the members of asteroid dynamical families

Sufentanil sublingual tablet system. From rationale of use to clinical practice

The control of post-operative pain in Italy and other western countries is still suboptimal. In recent years, the Sufentanil Sublingual Tablet System (SSTS; Zalviso; AcelRx Pharmaceuticals, Redwood City, CA, USA), which is designed for patient-controlled analgesia (PCA), has entered clinical practice. SSTS enables patients to manage moderate-to-severe acute pain during the first 72 postoperative hours directly in the hospital setting. However, the role of SSTS within the current framework of options for the management of post-operative pain needs to be better established. This paper presents the position on the use of SSTS of a multidisciplinary group of Italian Experts and provides protocols for the use of this device

Minor-but-Complex Liver Resection: An Alternative to Major Resections for Colorectal Liver Metastases Involving the Hepato-Caval Confluence

Major hepatectomy (MH) is often considered the only possible approach for colorectal liver metastasis (CRLM) at the hepato-caval confluence (CC), but it is associated with high morbidity and mortality. With the aim to reduce MH, we developed the "minor-but-complex" (MbC) technique, which consists in the resection of less than 3 adjacent liver segments with exposure of the CC and preservation of hepatic outflow until spontaneous maturation of peripheral intrahepatic shunts between main hepatic veins. We have evaluated applicability and outcome of MbC resections for the treatment of CRLM involving the CC. In this retrospective cohort study, all consecutive liver resections (LR) performed for CRLM located in segments 1, 7, 8, or 4a were classified as MINOR - removal of bC - removal of = 3 adjacent segments. The rate of avoided MH was obtained by the difference between the rate of potentially MH (PMH) plus potentially inoperable cases and the rate of the MH performed. Taking into account that postoperative mortality is mainly related to the amount of resected liver, MbC was compared with minor resections for safety, complexity, and outcome. Of the 59 LR analyzed, 29 (49.1%) were deemed PMH and 4 (6.8%) potentially inoperable. Eventually, MH was performed only in 8 (13.5%) with a decrease rate of 42.4%. Minor LR was performed in 23 (39.0%) and MbC LR in 28 (47.5%) patients. Among MbC cases, 32.1% had previous liver treatments, 39.3% required vascular reconstruction (no reconstructed vessel thrombosis occurred before maturation of peripheral intrahepatic shunts between main hepatic veins), and 7.1% had grade IIIb-IV complications, their median hospital stay was 9 days and 90-day mortality was 0%. After a median follow-up of 22.2 months, oncological results were comparable with those of minor resections. MbC hepatectomy lowers the need for MH and allows for the resection of potentially inoperable patients without negative impact on safety and survival

Evaluation of direct immunofluerescence test for Campylobacter fetus in bull experimentally infected and commensal bacteria from the reproductive tract of bulls

Campylobacter fetus is a Gram negative bacterium, with 2 relevant subspecies for cattle health: C. fetus subsp. fetus (Cff) and C. fetus subsp. venerealis (Cfv) which cause important reproductive losses. In the present work, four groups of bulls were used: one group to characterize the genital microbiota (G1; n=3) and the other three to evaluate the direct immunofluorescence (DIF) test for the diagnosis of bovine campylobacteriosis in preputial samples (PS) from experimentally infected bulls with Cff (G2; n=3) and Cfv (G3; n=3), and controls (G4; n=4). Seven bacterial strains of different genera were identified in the PS from G1. Other 11 laboratory bacterial strains were included: Cff, Cfv and Cfv biovar Intermedius, 3 Campylobacter non-fetus, 3 Gram negative and 2 Gram positive. Only the C. fetus strains presented positive immunostaining. The sensitivity and specificity of the DIF test were 79 % and 100 %, respectively. Concordance between DIF test and bacteriological culture was 83 % (Kappa index: 0.65). The present study shows the high specificity of the DIF test for detection of C. fetus using a fluorescent conjugate elaborated in Argentina, and highlights the relevance of no cross reaction against 15 bacterial strains normally present in bull preputial microbiota.Campylobacter fetus es una bacteria Gram negativa que incluye 2 subespecies de relevancia sanitaria para el bovino: C. fetus subsp. fetus (Cff) y C. fetus subsp. venerealis (Cfv), causantes de importantes pérdidas reproductivas. En el presente estudio, se utilizaron cuatro grupos de toros: un grupo (G1) para caracterizar la microbiota genital, y otros tres (G2, G3, G4) (n=10) para evaluar el test de inmunofluorescencia directa (IFD) para el diagnóstico de la campilobacteriosis bovina en esmegma prepucial (EP) de toros experimentalmente infectados con Cff y Cfv. Se identificaron siete cepas bacterianas de distinto género del G1. Otras 11 cepas bacterianas de laboratorio fueron incluidas: Cff, Cfv, Cfv biovar Intermedius, 3 Campylobacter no-fetus, 3 Gram negativo y 2 Gram positivo. Solo las cepas de C. fetus presentaron inmunofluorescencia positiva. La sensibilidad y especificidad de la IFD fue de 79 % y 100 %, respectivamente. La concordancia entre la IFD y el cultivo bacteriológico fue de 83 % (Kappa: 0,65). Se demuestra la alta especificidad de la IFD para la detección de C. fetus con un conjugado fluorescente elaborado en Argentina, y se destaca la no reacción cruzada contra 15 cepas bacterianas normalmente presentes en la microbiota prepucial del toro.Fil: García, Juan Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Soto, J.. Laboratorio Biologico de Tandil ; ArgentinaFil: Soto, P.. Laboratorio Biologico de Tandil Srl.; ArgentinaFil: Malena, Rosana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Morsella, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Méndez, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Fiorentino, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Paz Acuña, Joaquín Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Lucchesi, Enrique. Laboratorio Biologico de Tandil ; ArgentinaFil: Paolicchi, Fernando Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; Argentin

Collisional processes and size distribution in spatially extended debris discs

We present a new multi-annulus code for the study of collisionally evolving extended debris discs. We first aim to confirm results obtained for a single-annulus system, namely that the size distribution in "real" debris discs always departs from the theoretical collisional equilibrium dN\proptoR^{-3.5}dR power law, especially in the crucial size range of observable particles (<1cm), where it displays a characteristic wavy pattern. We also aim at studying how debris discs density distributions, scattered light luminosity profiles, and SEDs are affected by the coupled effect of collisions and radial mixing due to radiation pressure affected small grains. The size distribution evolution is modeled from micron-sized grains to 50km-sized bodies. The model takes into account the crucial influence of radiation pressure-affected small grains. We consider the collisional evolution of a fiducial a=120AU radius disc with an initial surface density in $\Sigma(a)\propto a^{\alpha}$. We show that the system's radial extension plays a crucial role: in most regions the collisional and size evolution of the dust is imposed by small particles on eccentric or unbound orbits produced further inside the disc. The spatial distribution of small grains strongly departs from the initial profile, while the bigger objects, containing most of the system's mass, still follow the initial distribution. This has consequences on the scattered--light radial profiles which get significantly flatter, and we propose an empirical law to trace back the distribution of large unseen parent bodies from the observed profiles. We finally provide empirical formula for the collisional size distribution and collision timescale that can be used for future debris disc modeling.Comment: Accepted for publication in Astronomy and Astrophysics (with better figures) (note: full abstract in the *.pdf file

Report of mycobacteria isolated from domestic and wildlife species during 2004-2008

La identificación de la tuberculosis bovina y su diferenciación de las micobacteriosis es fundamental durante el diagnóstico. Es por eso que los laboratorios especializados en micobacterias son de suma importancia en los servicios de salud pública y salud animal. El objetivo de la presente investigación es diferenciar Mycobacterium bovis de micobacterias no tuberculosas en cepas cultivadas a partir de especies domésticas y silvestres de siete provincias de Argentina durante 2004-2008. La diferenciación se basó sobre las pruebas bioquímicas, las características fenotípicas y el “spolygotyping” de M. bovis. Con la identificación bioquímica y fenotípica se detectaron 20 cepas de M. bovis, 18 de las cuales fueron confirmadas mediante “spolygotyping”, y 34 cepas de micobacterias no tuberculosas. Trece especies fueron caracterizadas y todas ellas fueron agrupadas considerando el riesgo biológico y el potencial patógeno notificado en seres humanos y/o animales. En este trabajo se han logrado avances en el diagnóstico de tuberculosis y micobacteriosis en medicina veterinaria. En este área el diagnóstico habitualmente se basa sobre la observación micro y macroscópica de los tubérculos y los resultados de la intradermorreacción. Estos avances son importantes porque la tuberculosis zoonótica aún es un problema de salud pública en América Latina.Detection and identification of bovine tuberculosis and its differentiation from micobacteriosis is fundamental during diagnoses. That is why mycobacteria laboratories improvement becomes essential in public health and veterinary medicine services. The objective of the present research is to differentiate Mycobacterium bovis and nontuberculous mycobacterias in isolates cultured from domestic and wildlife species from seven Argentinean provinces during 2004-2008. Differentiation was based on biochemical tests, phenotypic characteristics and M. bovis spolygotyping. Biochemical and phenotypic identification resulted in 20 M. bovis strains, 18 of them were confirmed by spolygotyping, and 34 nontuberculous mycobacteria strains. Thirteen species were characterized and all of them were grouped considering biological risk and pathogenic potential reported in humans and/or animals. Here we have reached advances in tuberculosis and micobacteriosis diagnoses in veterinary medicine. In this area diagnoses are often based on micro and macroscopic observation of the tubercles and skin test results. These advances are not minor as zoonotic tuberculosis is still a public health problem in Latin America.Facultad de Ciencias Veterinaria