Primordial black holes from cosmic necklaces

Cosmic necklaces are hybrid topological defects consisting of monopoles and strings. We argue that primordial black holes(PBHs) may have formed from loops of the necklaces, if there exist stable winding states, such as coils and cycloops. Unlike the standard scenario of PBH formation from string loops, in which the kinetic energy plays important role when strings collapse into black holes, the PBH formation may occur in our scenario after necklaces have dissipated their kinetic energy. Then, the significant difference appears in the production ratio. In the standard scenario, the production ratio $f$ becomes a tiny fraction $f\sim 10^{-20}$, however it becomes $f \sim 1$ in our case. On the other hand, the typical mass of the PBHs is much smaller than the standard scenario, if they are produced in the same epoch. As the two mechanisms may work at the same time, the necklaces may have more than one channel of the gravitational collapse. Although the result obtained in this paper depends on the evolution of the dimensionless parameter $r$, the existence of the winding state could be a serious problem in some cases. Since the existence of the winding state in brane models is due to the existence of a non-tivial circle in the compactified space, the PBH formation can be used to probe the structure of the compactified space. Black holes produced by this mechanism may have peculiar properties.Comment: 22pages, 3 figures, added many comments, +1 figure, accepted for publication in JHE

Lower Cretaceous (Hauterivian-Albian) ammonite biostratigraphy in the Maestrat Basin (E Spain)

Peer reviewedPublisher PD

Cosmology and two-body problem of D-branes

In this paper, we investigate the dynamics and the evolution of the scale factor of a probe Dp-brane which move in the background of source Dp-branes. Action of the probe brane is described by the Born-Infeld action and the interaction with the background R-R field. When the probe brane moves away from the source branes, it expands by power law, whose index depends on the dimension of the brane. If the energy density of the gauge field on the brane is subdominant, the expansion is decelerating irrespective of the dimension of the brane. On the other hand, when the probe brane is a Nambu-Goto brane, the energy density of the gauge field can be dominant, in which case accelerating expansion occurs for $p \leq 4$. The accelerating expansion stops when the brane has expanded sufficiently so that the energy density of the gauge field become subdominant.Comment: 6 pages, 7 figures, reference added, accepted for publication in PR

TREX-DM: a low background Micromegas-based TPC for low mass WIMP detection

Dark Matter experiments are recently focusing their detection techniques in low-mass WIMPs, which requires the use of light elements and low energy threshold. In this context, we present the TREX-DM experiment, a low background Micromegas-based TPC for low-mass WIMP detection. Its main goal is the operation of an active detection mass $\sim$0.300 kg, with an energy threshold below 0.4 keVee and fully built with previously selected radiopure materials. This article describes the actual setup, the first results of the comissioning in Ar+2\%iC$_4$H$_{10}$ at 1.2 bar and the future updates for a possible physics run at the Canfranc Underground Laboratory in 2016. A first background model is also presented, based on Geant4 simulations and a muon/electron discrimination method. In a conservative scenario, TREX-DM could be sensitive to DAMA/LIBRA and other hints of positive WIMPs signals, with some space for improvement with a neutron/electron discrimination method or the use of other light gases.Comment: Proceedings of the 7th Symposium on Large TPCs for Low-Energy Rare Event Detectio

Promoting global clinical care and research for children with orthopaedic disabilities through motion analysis technology

Human motion analysis is a tool used to understand orthopaedic disabilities in children and to plan and monitor treatment strategies. It enables clinicians to quantitatively describe rehabilitative progress, plan surgeries, and conduct research. While this technology is prevalent in major academic medical centers, access is lacking in many regions throughout the world. This paper presents a novel approach to offer more accessible technology at greatly reduced cost. Current applications are underway in the Philippines, Mexico, and Colombia. Through international partnerships, improvements in clinical care, medical education, and research have been observed

Prognostic value of plasma pentraxin 3 levels in patients with septic shock admitted to intensive care

Objective: To evaluate the usefulness of a new marker, pentraxin, as a prognostic marker in septic shock patients. Materials and methods: Single-centre prospective observational study that included all consecutive patients 18 years or older who were admitted to the intensive care unit (ICU) with septic shock. Serum levels of procalcitonin (PCT), C reactive protein (CRP) and pentraxin (PTX3) were measured on ICU admission. Results: Seventy-five septic shock patients were included in the study. The best predictors of inhospital mortality were the severity scores: SAPS II (AUC = 0.81), SOFA (AUC = 0.79) and APACHE II (AUC = 0.73). The ROC curve for PTX3 (ng/mL) yielded an AUC of 0.70, higher than the AUC for PCT (0.43) and CRP (0.48), but lower than lactate (0.79). Adding PTX3 to the logistic model increased the predictive capacity in relation to SAPS II, SOFA and APACHE II for in-hospital mortality (AUC 0.814, 0.795, and 0.741, respectively). In crude regression models, significant associations were found between in-hospital mortality and PTX3. This positive association increased after adjusting for age, sex and immunosuppression: adjusted OR T3 for PTX3 = 7.83, 95% CI 1.35?45.49, linear P trend = 0.024. Conclusion: Our results support the prognostic value of a single determination of plasma PTX3 as a predictor of hospital mortality in septic shock patients

Dark matter production from cosmic necklaces

Cosmic strings have gained a great interest, since they are formed in a large class of brane inflationary models. The most interesting story is that cosmic strings in brane models are distinguished in future cosmological observations. If the strings in brane models are branes or superstrings that can move along compactified space, and also if there are degenerated vacua along the compactified space, kinks interpolate between degenerated vacua become ``beads'' on the strings. In this case, strings turn into necklaces. In the case that the compact manifold in not simply connected, a string loop that winds around a nontrivial circle is stable due to the topological reason. Since the existence of the (quasi-)degenerated vacua and the nontrivial circle is a common feature of the brane models, it is important to study cosmological constraints on the cosmic necklaces and the stable winding states. In this paper, we consider dark matter production from loops of the cosmic necklaces. Our result suggests that necklaces can put stringent bound on certain kinds of brane models.Comment: 27 pages, 5 figures, added many comments and 3 figures, accepted for publication in JCA

Ruling out four-neutrino oscillation interpretations of the LSND anomaly?

Prompted by recent solar and atmospheric data, we re-analyze the four-neutrino description of current global neutrino oscillation data, including the LSND evidence for oscillations. The higher degree of rejection for non-active solar and atmospheric oscillation solutions implied by the SNO neutral current result as well as by the latest 1489-day Super-K atmospheric neutrino data allows us to rule out (2+2) oscillation schemes proposed to reconcile LSND with the rest of current neutrino oscillation data. Using an improved goodness of fit (gof) method especially sensitive to the combination of data sets we obtain a gof of only 1.6 times 10^{-6} for (2+2) schemes. Further, we re-evaluate the status of (3+1) oscillations using two different analyses of the LSND data sample. We find that also (3+1) schemes are strongly disfavoured by the data. Depending on the LSND analysis we obtain a gof of 5.6 times 10^{-3} or 7.6 times 10^{-5}. This leads to the conclusion that all four-neutrino descriptions of the LSND anomaly, both in (2+2) as well as (3+1) realizations, are highly disfavoured. Our analysis brings the LSND hint to a more puzzling status.Comment: 21 pages, 7 figure

Searches for Giant Pulses from Extragalactic Pulsars

We discuss the giant-pulse phenomenon exhibited by pulsars and the distances to which giant pulses might be detected from extragalactic pulsars. We describe the conditions under which a single-pulse search is more sensitive than a standard periodicity search. We find that, for certain pulse-amplitude distribution power laws and time series lengths, single-pulse searches can be superior. We present the results of searches toward several extragalactic targets, including M33, the LMC (PSR B0540-69) and several other galaxies. While we have not conclusively detected giant pulses from any of these targets, these searches illustrate the methodology of, issues related to and difficulties in these types of searches.Comment: Accepted by Ap