2D and 3D data processing of archaeo-magnetic data

Introduction. The Sabine Necropolis at Colle del Forno (700-300 B.C.) at Montelibretti, Rome is characterized by dromos chamber tombs, most of them unexplored till now. The tombs can be assimilated to cavities of a standard volume of some cubic meters; the entrance of the tombs is a corridor 6 m long with a 1 square meter section . The surficial geology of the area consists of a series of tuffs about 10 m thick overlying Pleistocene-Quaternary sandy-clayey sediments. A thin layer of top soil (20 - 30 cm) covers the tuff. The investigation of the Necropolis in the past decade has been performed by different geophysical methodologies: electrical, electromagnetic and magnetic methods have been widely adopted to investigate several chamber tombs (Piro et al, 2001). The aim of this paper is to analyze an integrated approach to the processing of magnetic survey data. The magnetic susceptibility contrast between topsoil, subsoil and rocks (topsoil is normally more magnetic than subsoil) permits to detect ditches, pits and other silted-up features that were excavated and then silted or back-filled with topsoil. Meanwhile back-filled areas produce positive anomalies, less magnetic material introduced into topsoil, including many kinds of masonry (for example, limestone walls) may produce negative anomalies of the order of some nanoteslas. The same behavior is related to the presence of cultural voids and tombs whose magnetic anomaly is generated by the lack of magnetic materials due to the cavities of the tombs. In the area a diffused magnetisation is manly due to the presence of top soil and tuff materials and high negative susceptibility contrasts can be expected because of the presence of the tombs. The magnetic survey was performed along a regular grid of 0.5 m x 0.5 m using a optical pumped Caesium-vapour magnetometer G858 (Geometrics), in the gradient configuration, on an area which is well known as far as the presence, size and position of tombs are concerne

Transparent Helium in Stripped Envelope Supernovae

Using simple arguments based on photometric light curves and velocity evolution, we propose that some stripped envelope supernovae (SNe) show signs that a significant fraction of their helium is effectively transparent. The main pieces of evidence are the relatively low velocities with little velocity evolution, as are expected deep inside an exploding star, along with temperatures that are too low to ionize helium. This means that the helium should not contribute to the shaping of the main SN light curve, and thus the total helium mass may be difficult to measure from simple light curve modeling. Conversely, such modeling may be more useful for constraining the mass of the carbon/oxygen core of the SN progenitor. Other stripped envelope SNe show higher velocities and larger velocity gradients, which require an additional opacity source (perhaps the mixing of heavier elements or radioactive nickel) to prevent the helium from being transparent. We discuss ways in which similar analysis can provide insights into the differences and similarities between SNe Ib and Ic, which will lead to a better understanding of their respective formation mechanisms.Comment: Revised version accepted for publication in The Astrophysical Journal Letters, 4 pages, 4 figure

Exploring the Potential Diversity of Early Type Ia Supernova Light Curves

During the first several days after explosion, Type Ia supernova light curves probe the outer layers of the exploding star and therefore provide important clues for identifying their progenitors. We investigate how both the shallow $^{56}$Ni distribution and the presence of circumstellar material shape these early light curves. This is performed using a series of numerical experiments with parameterized properties for systematic exploration. Although not all of the considered models may be realized in nature (and indeed there are arguments why some of them should not occur), the spirit of this work is to provide a broader exploration of the diversity of possibilities. We find that shallower $^{56}$Ni leads to steeper, bluer light curves. Differences in the shape of the rise can introduce errors in estimating the explosion time and thus impact efforts to infer upper limits on the progenitor or companion radius from a lack of observed shock cooling emission. Circumstellar material can lead to significant luminosity during the first few days, but its presence can be difficult to identify depending on the degree of nickel mixing. In some cases, the hot emission of circumstellar material may even lead to a signature similar to interaction with a companion, and thus in the future additional diagnostics should be gathered for properly assessing early light curves.Comment: Revised version with additional figures and discussions. 8 pages, 15 figures, accepted for publication in The Astrophysical Journa

Resonant Shattering of Neutron Star Crusts

The resonant excitation of neutron star (NS) modes by tides is investigated as a source of short gamma-ray burst (sGRB) precursors. We find that the driving of a crust-core interface mode can lead to shattering of the NS crust, liberating ~10^46-10^47 erg of energy seconds before the merger of a NS-NS or NS-black hole binary. Such properties are consistent with Swift/BAT detections of sGRB precursors, and we use the timing of the observed precursors to place weak constraints on the crust equation of state. We describe how a larger sample of precursor detections could be used alongside coincident gravitational wave detections of the inspiral by Advanced LIGO class detectors to probe the NS structure. These two types of observations nicely complement one another, since the former constrains the equation of state and structure near the crust-core boundary, while the latter is more sensitive to the core equation of state.Comment: 5 pages, 2 figures. Accepted to PR

Blow-up time estimates in nonlocal reaction-diffusion systems under various boundary conditions

This paper deals with the question of blow-up of solutions to nonlocal reaction-diffusion systems under various boundary conditions. Specifically, conditions on data are introduced to avoid the blow-up of the solution, and when the blow-up occurs, explicit lower and upper bounds of blow-up time are derived

A note on a class of 4th order hyperbolic problems with weak and strong damping and superlinear source term

In this paper we study a initial-boundary value problem for 4th order hyperbolic equations with weak and strong damping terms and superlinear source term. For blow-up solutions a lower bound of the blow-up time is derived. Then we extend the results to a class of equations where a positive power of gradient term is introduced

Molecular dissection of Phaseolus vulgaris polygalacturonase-inhibiting protein 2 reveals the presence of hold/release domains affecting protein trafficking toward the cell wall

The plant endomembrane system is massively involved in the synthesis, transport and secretion of cell wall polysaccharides and proteins; however, the molecular mechanisms underlying trafficking toward the apoplast are largely unknown. Besides constitutive, the existence of a regulated secretory pathway has been proposed. A polygalacturonase inhibitor protein (PGIP2), known to move as soluble cargo and reach the cell wall through a mechanism distinguishable from default, was dissected in its main functional domains (A, B, C, D), and C sub-fragments (C1–10), to identify signals essential for its regulated targeting. The secretion patterns of the fluorescent chimeras obtained by fusing different PGIP2 domains to the green fluorescent protein (GFP) were analyzed. PGIP2 N-terminal and leucine-rich repeat domains (B and C, respectively) seem to operate as holding/releasing signals, respectively, during PGIP2 transit through the Golgi. The B domain slows down PGIP2 secretion by transiently interacting with Golgi membranes. Its depletion leads, in fact, to the secretion via default (Sp2-susceptible) of the ACD-GFP chimera faster than PGIP2. Depending on its length (at least the first 5 leucine-rich repeats are required), the C domain modulates B interaction with Golgi membranes allowing the release of chimeras and their extracellular secretion through a Sp2 independent pathway. The addition of the vacuolar sorting determinant Chi to PGIP2 diverts the path of the protein from cell wall to vacuole, suggesting that C domain is a releasing rather than a cell wall sorting signal

Iraqi Nurses' Perspectives on Safety Issues in Maternity Services

Background: Studies introduce maternal and neonatal safety phenomena as important challenges to the public health, particularly in low-income countries. However, few researches are conducted on the identification of safety issues in maternity hospitals in Iraq. It was the first study on nurses’ perspectives on safety issues in Kurdistan, Iraq. Objectives: The current study aimed to describe nurses’ perspectives on what constitutes a safe maternity service in Kurdistan, Iraq. Patients and Methods: A qualitative design, based on a content analysis approach, was used. Ten Kurdish nurses who worked in the delivery room of Kurdistan, Iraq maternity hospital were recruited through purposive sampling. Semi-structured interviews were performed to collect data. All interviews were audiotaped and transcribed verbatim. Sampling continued to the level of data saturation. Data analysis was performed based on the steps suggested by Graneheim and Lundman. Results: Thematic analysis led to the identification of six main categories including stressful job, lack of schedule and job description, providing care with limited resources, professional unaccountability, regional sociopolitical factors, and inadequate training. Conclusions: Iraqi nurses identified factors such as limited health resources, lack of job description, and professional unaccountability as major safety issues in maternity services. These findings alarm the need to ensure the provision of females and neonates with appropriate care. This, however, would require coordination between Iraqi Kurdistan health authorities to provide midwifery care facilities, high-quality and relevant staff training, and an effective healthcare system in the maternity units

The Non-Relativistic Evolution of GRBs 980703 and 970508: Beaming-Independent Calorimetry

We use the Sedov-Taylor self-similar solution to model the radio emission from the gamma-ray bursts (GRBs) 980703 and 970508, when the blastwave has decelerated to non-relativistic velocities. This approach allows us to infer the energy independent of jet collimation. We find that for GRB 980703 the kinetic energy at the time of the transition to non-relativistic evolution, t_NR ~ 40 d, is E_ST ~ (1-6)e51 erg. For GRB 970508 we find E_ST ~ 3e51 erg at t_NR ~ 100 d, nearly an order of magnitude higher than the energy derived in Frail, Waxman and Kulkarni (2000). This is due primarily to revised cosmological parameters and partly to the maximum likelihood fit we use here. Taking into account radiative losses prior to t_NR, the inferred energies agree well with those derived from the early, relativistic evolution of the afterglow. Thus, the analysis presented here provides a robust, geometry-independent confirmation that the energy scale of cosmological GRBs is about 5e51 erg, and additionally shows that the central engine in these two bursts did not produce a significant amount of energy in mildly relativistic ejecta at late time. Furthermore, a comparison to the prompt energy release reveals a wide dispersion in the gamma-ray efficiency, strengthening our growing understanding that E_gamma is a not a reliable proxy for the total energy.Comment: Submitted to ApJ; 13 pages, 6 figures, 1 table; high-resolution figures can be found at: http://www.astro.caltech.edu/~ejb/NR