Ready, Set, Launch: Time Interval between a Binary Neutron Star Merger and Short Gamma-Ray Burst Jet Formation

The joint detection of GW170817/GRB 170817 confirmed the long-standing theory that binary neutron star mergers produce short gamma-ray burst (sGRB) jets that can successfully break out of the surrounding ejecta. At the same time, the association with a kilonova provided unprecedented information regarding the physical properties (such as masses and velocities) of the different ejecta constituents. Combining this knowledge with the observed luminosities and durations of cosmological sGRBs detected by the Burst Alert Telescope onboard the Neil Gehrels Swift Observatory, we revisit the breakout conditions of sGRB jets. Assuming self-collimation of sGRB jets does not play a critical role, we find that the time interval between the binary merger and the launch of a typical sGRB jet is ≾0.1 s. We also show that for a fraction of at least ~30% of sGRBs, the usually adopted assumption of static ejecta is inconsistent with observations, even if the polar ejecta mass is an order of magnitude smaller than that in GRB 170817. Our results disfavor magnetar central engines for powering cosmological sGRBs, limit the amount of energy deposited in the cocoon prior to breakout, and suggest that the observed delay of ~1.7 s in GW170817/GRB 170817 between the gravitational wave and gamma-ray signals is likely dominated by the propagation time of the jet to the gamma-ray production site

Shedding light on the prompt high efficiency paradox - self consistent modeling of GRB afterglows

We examine GRBs with both Fermi-LAT and X-ray afterglow data. Assuming that the 100MeV (LAT) emission is radiation from cooled electrons accelerated by external shocks, we show that the kinetic energy of the blast wave estimated from the 100MeV flux is 50 times larger than the one estimated from the X-ray flux. This can be explained if either: i) electrons radiating at X-rays are significantly cooled by SSC (suppressing the synchrotron flux above the cooling frequency) or ii) if the X-ray emitting electrons, unlike those emitting at 100MeV energies, are in the slow cooling regime. In both cases the X-ray flux is no longer an immediate proxy of the blast wave kinetic energy. We model the LAT, X-ray and optical data and show that in general these possibilities are consistent with the data, and explain the apparent disagreement between X-ray and LAT observations. All possible solutions require weak magnetic fields: $10^{-6}< \epsilon_B < 10^{-3}$ (where $\epsilon_B$ is the fraction of shocked plasma energy in magnetic fields). Using the LAT emission as a proxy for the blast wave kinetic energy we find that the derived prompt efficiencies are of order 15%. This is considerably lower compared with previous estimates (87% and higher for the same bursts). This provides at least a partial solution to the "prompt high efficiency paradox".Comment: 8 pages, 2 figures, proceedings of "Swift: 10 Years of Discovery

Energies of GRB blast waves and prompt efficiencies as implied by modeling of X-ray and GeV afterglows

We consider a sample of ten GRBs with long lasting ($\gtrsim10^2\rm\,sec$) emission detected by Fermi/LAT and for which X-ray data around $1\,$day are also available. We assume that both the X-rays and the GeV emission are produced by electrons accelerated at the external forward shock, and show that the X-ray and the GeV fluxes lead to very different estimates of the initial kinetic energy of the blast wave. The energy estimated from GeV is on average $\sim50$ times larger than the one estimated from X-rays. We model the data (accounting also for optical detections around $1\,$day, if available) to unveil the reason for this discrepancy and find that good modelling within the forward shock model is always possible and leads to two possibilities: either the X-ray emitting electrons (unlike the GeV emitting electrons) are in the slow cooling regime or ii) the X-ray synchrotron flux is strongly suppressed by Compton cooling, whereas, due to the Klein-Nishina suppression, this effect is much smaller at GeV energies. In both cases the X-ray flux is no longer a robust proxy for the blast wave kinetic energy. On average, both cases require weak magnetic fields ($10^{-6}\lesssim \epsilon_B \lesssim 10^{-3}$) and relatively large isotropic kinetic blast wave energies $10^{53}\rm\,erg<E_{0,kin}<10^{55}\rm\,erg$ corresponding to large lower limits on the collimated energies, in the range $10^{52}\rm\,erg<E_{\theta,kin}<5\times10^{52}\rm\,erg$ for an ISM environment with n\sim 1\mbox{cm}^{-3} and $10^{52}\rm\,erg<E_{\theta,kin}<10^{53}\rm\,erg$ for a wind environment with $A_* \sim 1$. These energies are larger than those estimated from the X-ray flux alone, and imply smaller inferred values of the prompt efficiency mechanism, reducing the efficiency requirements on the still uncertain mechanism responsible for prompt emission.Comment: 14 pages, 7 figures. Accepted for publication in MNRA

Effectiveness of Protected Areas and Implications for Conservation of Biodiversity and Ecosystem Services

Protected areas (PAs) are considered a key strategy to ensure the in situ persistence of biodiversity and the ecosystem services (ES) that this provides. The coverage of PAs has exponentially expanded in the last 25 years, and they now account for approximately 13% of the Earth's surface. Alongside this expansion, PA research literature has also increased seeking to identify and assess the main factors that influence the effectiveness of PAs in sheltering biodiversity and ES from anthropogenic pressures. Spatial distribution, spatial design, management strategy and threats, have been widely acknowledged as key factors. However, despite significant progress, several aspects of these factors remain poorly explored. This thesis aims to identify and address some of the gaps, which I detail below. The second chapter contributes to understanding of how the distribution of PAs affects the representation of biodiversity and ES. To this end, the Chilean PA system was used as a case study as this has never been previously assessed in terms of ES. I found that the strong bias in Chilean PAs distribution toward southern areas, which contain mainly ice and bare rock, hampers the PA system in achieving effective representativeness. The third and fourth chapters address some gaps in PA spatial design. The third assesses for the first time the spatial design of the global PA system and provides new methodologies to achieve this at such a large scale. Focusing on the size, shape, level of fragmentation, occurrence of buffer zones and proximity to the closest PA, I demonstrate that PAs tend to be small, irregularly shaped and fragmented. However, they are often close to one another and generally have buffer zones. Using the methodology generated on third chapter, I explicitly test in the fourth chapter the combined and interactive effects of PA spatial features on their ability to represent biodiversity, which has never been tested before. Using South America as a model for study I show that the spatial design largely explains biodiversity representation and that the interaction between spatial features affects the latter. The fifth chapter focuses on threats to PAs, assessing the extent to which metal mining activities represent an actual conflict with the global PA system. Evidence suggests that the global terrestrial PA system has been effective at displacing metal mining activities from within its bounds. However, given the high proportion of mines found in the close surroundings of PAs, and the distances over which mining activities can have influences, it is highly likely that the conservation performance of a significant proportion of PAs is being affected. So far I have demonstrated that PAs are not always optimally distributed and they can compete with other land uses, which can undermine their functionality. In this regard, in the final analytical chapter I explore how using spatial conservation prioritization (SCP) tools it is possible to optimize the representation of conservation features by minimizing competition with other land uses. Specifically, I assess the consequences for biodiversity and ES representation of incorporating land use trade-offs in SCP analyses. I show that the dichotomist decision of treating a land use as a trade-off or not can have enormous consequences on biodiversity and ES representation, and the implications of such decisions have to be considered before policy recommendations. This thesis shows that distribution, spatial design and threats play an important role in PA representativeness, and that SCP techniques can make a significant contribution to balancing biodiversity and ES conservation with human activities, when trade-offs are treated comprehensively. Finally, I discuss the importance of prioritising the interactions between, rather than just individual effects of, factors in order to optimise PA effectiveness and the distribution of scarce conservation resources

Ready, Set, Launch: Time Interval between a Binary Neutron Star Merger and Short Gamma-Ray Burst Jet Formation

The joint detection of GW170817/GRB 170817 confirmed the long-standing theory that binary neutron star mergers produce short gamma-ray burst (sGRB) jets that can successfully break out of the surrounding ejecta. At the same time, the association with a kilonova provided unprecedented information regarding the physical properties (such as masses and velocities) of the different ejecta constituents. Combining this knowledge with the observed luminosities and durations of cosmological sGRBs detected by the Burst Alert Telescope onboard the Neil Gehrels Swift Observatory, we revisit the breakout conditions of sGRB jets. Assuming self-collimation of sGRB jets does not play a critical role, we find that the time interval between the binary merger and the launch of a typical sGRB jet is ≾0.1 s. We also show that for a fraction of at least ~30% of sGRBs, the usually adopted assumption of static ejecta is inconsistent with observations, even if the polar ejecta mass is an order of magnitude smaller than that in GRB 170817. Our results disfavor magnetar central engines for powering cosmological sGRBs, limit the amount of energy deposited in the cocoon prior to breakout, and suggest that the observed delay of ~1.7 s in GW170817/GRB 170817 between the gravitational wave and gamma-ray signals is likely dominated by the propagation time of the jet to the gamma-ray production site

A dimeric inhibitor of insect a-amylase from barley. Cloning of the cDNA and identification of the protein

A cDNA clone, designated pUP-44, whose longest open reading frame codes for a protein that is homologous to the wheat α-amylase inhibitors, has been isolated from a library obtained from developing barley endosperm. The deduced sequence for the mature protein, which is 122 residues long, is preceded by a sequence of 30 residues which has the typical features of a signal peptide. A closely corresponding protein, designated BDAI-1, has been isolated from mature endosperm. BDAI-1 behaves as a dimer and inhibits the α-amylase from the insect Tenebrio molitor at concentrations that have no effect on salivary or pancreatic α-amylases

The CM-proteins from cereal endosperm: Immunochemical relationships

The CM-proteins, which are salt-soluble proteins that can be extracted with chloroform: methanol (2: 1, v/v), seem to be present in the endosperm of all the cereal species investigated. Antibodies raised against a mixture of the barley CM-proteins (A-H) cross-reacted with wheat and rye proteins in Ouchterlony tests and a detailed study was carried out for purified wheat (CM1, CM2. CM3. CM3') and barley (CMa, CMb, CMc, CMd) CM-proteins. [35Sl-Cysteine-labelled endosperm proteins from wheat and barley were investigated by immuno-precipitation, electrophoresis and fluorography using the antibodies (A-H) and also those to a mixture of wheat CM-proteins and to CMd. There was complete antigenic identity for all the wheat proteins and CMd, some of the other proteins showed partial antigenic identity. Previously proposed genetic and biochemical relationships among these proteins were confirmed in the present study

Assessment of soil surface roughness decay at semiarid field conditions using the shadow analysis method

Soil surface roughness (SSR) is an excellent parameter to assess soil vulnerability to wind and water erosion. Several methods are used to measure SSR depending on specific field and climate conditions. The method based on the shadow analysis has shown to be the most convenient technique to characterize SSR in the field than existing procedures when used in arid and semi-arid regions of Spain. This convenience is due to climate and soil conditions prevailing and low development and maintenance costs and adaptability. Therefore, the present study aimed to assess the SSR decay using the shadow analysis method at field in eight controlled plots of 1 m2. The data were collected from beginning of fall 2009 to spring 2010. Half of the experimental plots were covered to be used as control, to avoid influence from wind and water erosion. The rest of the plots were uncovered to assure SSR decay and to evaluate the parameter as the result of the produced erosion. The results showed marked differences among the cover an uncover plots. The parameters demonstrated that the method can be used to study the influence of wind and water erosion on soil at field conditions, although some adjustments must be done on method since it presents some limitations, mainly related to weather conditions when used continuously at field condition

Chromosomal location and expression of genes encoding low molecular weight proteins in wheat and related species

A review of recent work on the chromosomal location and expression of genes encoding moderately abundant, presumably non-storage endosperm proteins from wheat, barley and rye is presented. Related aspects, such as regulatory genetic effects, in vivo and in vitro synthesis, types of processing, deposition sites, and molecular cloning are also discussed. The relevance of these studies in connection with basic endosperm biology, genetic manipulation of quality and agronomic traits, and the evolution of these important crops is briefly emphasized