Olivine on Vesta as exogenous contaminants brought by impacts: Constraints from modeling Vesta's collisional history and from impact simulations

The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites and interpreted as the result of the excavation of endogenous olivine. Later works raised the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work we quantitatively explore the proposed scenario of a exogenous origin for the detected olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid. We took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, which we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by impacts can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite-Eucrite-Diogenite family of meteorites.Comment: 24 pages, 6 figures, accepted for publication on the journal Icaru

USE OF GASEOUS OZONE AS A DISINFECTANT IN MEAT INDUSTRY

The aim of this study was to investigate the possible use of gaseous ozone as a disinfectant for meat industry environments. Firstly microbial inactivation trials were conducted in laboratory conditions on Petri plates inoculated with some microorganisms of importance to the food industry. The treatment with 1 ppm of ozone resulted to be effective in 1 h on the strains in use. Then similar trials were conducted in a meat industry, 1 ppm of ozone was supplied for 3 h. The results confirmed the antimicrobial efficacy of ozone even if it was less active than in laboratory conditions. A different sensibility among the microorganisms was observed, the most resistant being P. fluorescens and B. thuringiensis. Our results confirm the suitability of gaseous ozone as a disinfectant for meat industry environments and underline the need to calibrate ozone treatment parameters on the real environmental conditions of work-room

Child labour: a public health issue

Child labour is a global practice and has many negative outcomes. According to International Labour Organization, child labour is the important source of child exploitation and child abuse in the world today. The Human Rights Commission of Pakistan has estimated the number of Pakistani working children to be around 11-12 millions, out of which, at least, half the children are under the age of ten years. It portrays the society\u27s attitude towards child care. It is therefore, essential to break this vicious cycle and hence, enable the society to produce healthy citizens. This article analyzes the determinants of child labour in the Pakistani context and its implications for child\u27s life, in specific, and for the nation, in general, utilizing the model developed by Clemen-stone & McGuire (1991). Since this practice has complex web of causation, a multidisciplinary approach is required to combat this issue through proposed recommendations

New embedding model of general relativity

The string-model analog of general relativity is shown to be unphysically dependent on an embedding gauge. Moreover, an explicit example confirms that it is inequivalent to Einstein's theory

Spinning Test Particle in Kalb-Ramond background

In this work we explore the geodesic deviations of spinning test particles in a string inspired Einstein-Kalb Ramond background. Such a background is known to be equivalent to a spacetime geometry with torsion. We have shown here that the antisymmetric Kalb-Ramond field has significant effect on the geodesic deviation of a spinning test particle. A search for an observational evidence of such an effect in astrophysical experiments may lead to a better undestanding of the geometry of the background spacetime.Comment: 14 pages, Latex, 5 figure

Association of awareness about hepatitis C infection with patterns of health seeking behavior among hepatitis C patients in Karachi, Pakistan

Background: Hepatitis C infection is one of the significant causes of morbidity and mortality throughout the world. In Pakistan, hepatitis C infection rate is 4.8%, which is the second highest prevalence rate among all developing countries. This study aimed to identify the association between awareness about hepatitis C infection and pattern of health seeking behavior among patients living with hepatitis C in Karachi, Pakistan. Methods: A descriptive, cross-sectional study was conducted among 250 hepatitis C patients who were recruited from the Aga Khan University Hospital and the Civil Hospital Karachi, Pakistan between March and May 2013. Data were collected through a modified questionnaire on ‘awareness about hepatitis C and patterns of health seeking behavior among hepatitis C patients’. Results: We did not find any association between participants’ awareness of hepatitis C infection and their primary contact with a health care provider. However, this study found that only half of the study participants (52%) had correct knowledge of hepatitisC. The patterns of health seeking behavior showed that a majority of the study participants approached a medical doctor (n=368), followed by spiritual healers (n=206), and a few participants approached traditional healers (n=39) and homeopaths (n=11). Conclusions: The study did not find any association between the patients’ level of awareness about hepatitis C infection and their primary contact with health careproviders. However, it has been found that patterns of health seeking behavior are strongly related to the patients’ cultural practices and beliefs, which affect their choiceof health care providers. This study has provided a basis for planning interventional studies aimed at improving patients’ level of awareness about hepatitis C and their health seeking behavior

Using ecological propensity score to adjust for missing confounders in small area studies

Small area ecological studies are commonly used in epidemiology to assess the impact of area level risk factors on health outcomes when data are only available in an aggregated form. However, the resulting estimates are often biased due to unmeasured confounders, which typically are not available from the standard administrative registries used for these studies. Extra information on confounders can be provided through external data sets such as surveys or cohorts, where the data are available at the individual level rather than at the area level; however, such data typically lack the geographical coverage of administrative registries. We develop a framework of analysis which combines ecological and individual level data from different sources to provide an adjusted estimate of area level risk factors which is less biased. Our method (i) summarizes all available individual level confounders into an area level scalar variable, which we call ecological propensity score (EPS), (ii) implements a hierarchical structured approach to impute the values of EPS whenever they are missing, and (iii) includes the estimated and imputed EPS into the ecological regression linking the risk factors to the health outcome. Through a simulation study, we show that integrating individual level data into small area analyses via EPS is a promising method to reduce the bias intrinsic in ecological studies due to unmeasured confounders; we also apply the method to a real case study to evaluate the effect of air pollution on coronary heart disease hospital admissions in Greater London

Light-Driven Reversible Shaping of Individual Azopolymeric Micro-Pillars

Azopolymers are known to exhibit a strong light responsivity known as athermal photofluidization. Although the underlying physics is still under debate, athermal photofluidization has been demonstrated to trigger mass-migration according to the polarization of a proper illumination light. Here, a polymer blend is proposed wherein a commercial azo-polyelectrolyte is mixed with a passive polymer. The blend is patterned as an array of micro-pillars that are individually exposed to visible laser illumination. Thanks to the interplay between the two blend components, a reversible and controlled deformation of the micro-pillars by periodically tuning the laser polarization in time is demonstrated. A reduced mobility of the azo-compound allows to repeatibly elongate and rotate micro-pillars along specific directions, with no significant material flow outisde the initial volume and no significant degradation of the structure morphology over several cycles. The proposed work suggests new degrees of freedom in controlling the mechanical features of micro-patterned light-responsive materials that can be usefully exploited in many application fields

The patterns of health seeking behavior among patients with hepatitis C in Karachi, Pakistan

Background: The study aimed to assess the patterns of health seeking behavior and the level satisfaction with the health care providers among hepatitis C patients in Karachi, Pakistan. Methodology: A descriptive, cross-sectional study was conducted among 250 hepatitis C patients, who were recruited from the Aga Khan University Hospital and the Civil Hospital Karachi, Pakistan, between March and May 2013. Results: The patterns of health seeking behavior showed that a majority of the study participants approached a medical doctor (n=359), followed by spiritual healers (n=103), and a few participants approached traditional healers (n=38) and homeopaths (n=11). The pattern of health seeking behavior also revealed that the participants were taking treatment from more than one health care provider at the same time. Participants who visited doctors had effective treatment outcomes and they were satisfied with their doctors. However, those participants who visited homeopaths, traditional healers and spiritual healers had ineffective treatment outcomes and they were not satisfied with these health care providers. Conclusion: The patterns of health seeking behavior are strongly related to the patients\u27 cultural practices and beliefs, which affect their choice of health care providers. This study has provided a basis for planning interventional studies aimed at improving patients\u27 health seeking behaviors

Geodesic Deviation Equation in Bianchi Cosmologies

We present the Geodesic Deviation Equation (GDE) for the Friedmann-Robertson-Walker(FRW) universe and we compare it with the equation for Bianchi type I model. We justify consider this cosmological model due to the recent importance the Bianchi Models have as alternative models in cosmology. The main property of these models, solutions of Einstein Field Equations (EFE) is that they are homogeneous as the FRW model but they are not isotropic. We can see this because they have a non-null Weyl tensor in the GDE.Comment: Submitted to Journal of Physics: Conference Series (JPCS), ERE200