Electronic Transport in Dual-gated Bilayer Graphene at Large Displacement Fields

We study the electronic transport properties of dual-gated bilayer graphene devices. We focus on the regime of low temperatures and high electric displacement fields, where we observe a clear exponential dependence of the resistance as a function of displacement field and density, accompanied by a strong non-linear behavior in the transport characteristics. The effective transport gap is typically two orders of magnitude smaller than the optical band gaps reported by infrared spectroscopy studies. Detailed temperature dependence measurements shed light on the different transport mechanisms in different temperature regimes.Comment: 4 pages, 3 figure

Modern political views and the emergence of early complex societies in the Bronze Age Mediterranean

The Tea Party, the Arab Spring and the Occupy movements may seem to have little in common. They respond to very different circumstances, and they are fuelled by very different ideologies. Furthermore, they do not represent homogeneous movements and each of them amalgamates very different groups with very different interests. Stripped of their most obvious traits, however, they share a common dissatisfaction with the nature of power in the present world, and each has opened a debate on the nature and legitimacy of current power structures

Primary State Formation Processes on Bronze Age Crete: A Social Approach to Change in Early Complex Societies

The formation of a state on Crete at the beginning of the second millennium bc has usually been considered under the secondary state paradigm. Most explanations rely on the role of conspicuous consumption and emulation mechanisms at a time when Cretan elites were exposed to the developed stratified systems of the east Mediterranean. A careful review of the data, especially those derived from funerary contexts, struggles to identify such dynamics but reveals a varied range of identities being negotiated and redefined simultaneously at the local and regional level. Informed by ethnographic parallels, an alternative model for Crete is proposed in which change is understood as a social phenomenon that involved a wide proportion of the population and brought broad benefits that sustained the adoption and development of the transformed systems. Crete is presented as a rich archaeological example that may also help in rethinking similar processes in other parts of the Mediterranean and further afield

101 ways of creating collective burials. The exceptional Cretan tombs in the context of the 3rd Millennium BC Mediterranean

Large collective tombs2 seem to be a popular feature across the Mediterranean and most of continental Europe from the end of the Neolithic into the first phases of the Bronze Age (ca. 4000-2000 BC). Collective burial deposits were just one of the several types of interments that formed the complex funerary customs of the period, but their significance at this time is unparalleled in European history since. Amongst the popularity of collective tombs in the 4th and 3rd millennium BC, Crete proves to be exceptional due to the almost exclusive use of tombs with commingled burial deposits for more than a millennium (ca. 3200-1800 BC; see figure 7.1 for chronology), which contrasts starkly against the burial variability in most other Mediterranean regions. At the same time, this is a millennium in which the island’s communities saw major changes in their size and complexity with significant developments in demography, settlement patterns, economic and political organisation. One cannot but feel that the effort and resources put on the Cretan collective tombs mark them as an important social arena at the forefront of these changes and that the exceptional burial record may have played a role in the development and sustainability of complex societies in the island at a moment when these were extremely rare across the Mediterranean. This article analyses this Cretan exceptionality in its Mediterranean context by reviewing the newly published bioarchaeological and taphonomic data from the tombs and contextualising it within the rich knowledge of the funerary record that has been developed in the last two decades

Recent developments in the study of Early Bronze Age Crete (Early Minoan period)

The production and publication of new research on the Cretan Early Bronze has accelerated tremendously in recent decades. This article aims to present the highlights and main trends of the last 15 years: the sites, excavations, research projects and main publications. Moreover, it explores how the new data interlink with the extremely large body of information available from more than 100 years of archaeological studies on Crete. The aim of such a review is to identify patterns of research, popular themes and the strengths and weaknesses of the data recovered, and to consider the place of Early Bronze Crete in current trends in the fields of Mediterranean Prehistory and archaeology more broadly

Prediction of destructive properties using descriptive analysis of nd measurements

Three groups of measurements related to peach maturity were acquired through destructive (D) mechanical tests (Magness Taylor Firmness, MTF), mechanical non destructive (ND) tests, and ND optical spectroscopy (Optical indexes). The relationship between these groups of variables was studied in order to estimate D mechanical measurements (MTF, with higher instrumental and sampling variability, time consuming, generally used as a reference for the assessment of peach handling), from ND measurements (quick, applicable on line, dealing better with the high variability found in fruit products). Multivariate exploratory analysis was used to extract the structure of the data. The information about the data structure of ND measurements, the relationship of MTF with the space defined by ND variables, and the expert knowledge regarding to the dataset was then used for modelling MTF (R 2 =0.72 and standard error on validation 5.73 N

Universality in Blow-Up for Nonlinear Heat Equations

We consider the classical problem of the blowing-up of solutions of the nonlinear heat equation. We show that there exist infinitely many profiles around the blow-up point, and for each integer $k$, we construct a set of codimension $2k$ in the space of initial data giving rise to solutions that blow-up according to the given profile.Comment: 38 page

Interpretation of increased energetic particle flux measurements by SEPT aboard the STEREO spacecraft and contamination

Context. Interplanetary (IP) shocks are known to be accelerators of energetic charged particles observed in-situ in the heliosphere. However, the acceleration of near-relativistic electrons by shocks in the interplanetary medium is often questioned. On 9 August 2011 a Corotating Interaction Region (CIR) passed STEREO B (STB) that resulted in a flux increase in the electron and ion channels of the Solar Electron and Proton Telescope (SEPT). Because electron measurements in the few keV to several 100 keV range rely on the so-called magnet foil technique, which is utilized by SEPT, ions can contribute to the electron channels. Aims. We aim to investigate whether the flux increase in the electron channels of SEPT during the CIR event on 9 August 2011 is caused by ion contamination only. Methods. We compute the SEPT response functions for protons and helium utilizing an updated GEANT4 model of SEPT. The CIR energetic particle ion spectra for protons and helium are assumed to follow a Band function in energy per nucleon with a constant helium to proton ratio. Results. Our analysis leads to a helium to proton ratio of 16.9% and a proton flux following a Band function with the parameters $I_0 = 1.24 \cdot 10^4$ / (cm2 s sr MeV/nuc.), $E_c = 79$ keV/nuc. and spectral indices of $\gamma_1 = -0.94$ and $\gamma_2 = -3.80$ which are in good agreement with measurements by the Suprathermal Ion Telescope (SIT) aboard STB. Conclusions. Since our results explain the SEPT measurements, we conclude that no significant amount of electrons were accelerated between $55$ keV and $425$ keV by the CIR

Improved determination of the 1(0)-0(0) rotational frequency of NH3D+ from the high resolution spectrum of the v4 infrared band

The high resolution spectrum of the v4 band of NH3D+ has been measured by difference frequency IR laser spectroscopy in a multipass hollow cathode discharge cell. From the set of molecular constants obtained from the analysis of the spectrum, a value of 262817(6) MHz (3sigma) has been derived for the frequency of the 1(0)-0(0) rotational transition. This value supports the assignment to NH3D+ of lines at 262816.7 MHz recorded in radio astronomy observations in Orion-IRc2 and the cold prestellar core B1-bS.Comment: Accepted for publication in the Astrophysical Journal Letters 04 June 201

Testing Supersymmetry with Lepton Flavor Violating tau and mu decays

In this work the following lepton flavor violating $\tau$ and $\mu$ decays are studied: $\tau^- \to \mu^- \mu^- \mu^+$, $\tau^- \to e^- e^- e^+$, $\mu^- \to e^- e^- e^+$, $\tau^- \to \mu^- \gamma$, $\tau^- \to e^- \gamma$ and $\mu^- \to e^- \gamma$. We work in a supersymmetric scenario consisting of the minimal supersymmetric standard model particle content, extended by the addition of three heavy right handed Majorana neutrinos and their supersymmetric partners, and where the generation of neutrino masses is done via the seesaw mechanism. Within this context, a significant lepton flavor mixing is generated in the slepton sector due to the Yukawa neutrino couplings, which is transmited from the high to the low energies via the renormalization group equations. This slepton mixing then generates via loops of supersymmetric particles significant contributions to the rates of $l_j \to 3 l_i$ and the correlated $l_j \to l_i \gamma$ decays. We analize here in full detail these rates in terms of the relevant input parameters, which are the usual minimal supergravity parameters and the seesaw parameters. For the $l_j \to 3 l_i$ decays, a full one-loop analytical computation of all the contributing supersymmetric loops is presented. This completes and corrects previous computations in the literature. In the numerical analysis compatibility with the most recent experimental upper bounds on all these $\tau$ and $\mu$ decays, with the neutrino data, and with the present lower bounds on the supersymmetric particle masses are required. Two typical scenarios with degenerate and hierarchical heavy neutrinos are considered. We will show here that the minimal supergravity and seesaw parameters do get important restrictions from these $\tau$ and $\mu$ decays in the hierarchical neutrino case.Comment: Version to appear in Physical Review