The role of stationarity in magnetic crackling noise

We discuss the effect of the stationarity on the avalanche statistics of Barkhuasen noise signals. We perform experimental measurements on a Fe$_{85}$B$_{15}$ amorphous ribbon and compare the avalanche distributions measured around the coercive field, where the signal is stationary, with those sampled through the entire hysteresis loop. In the first case, we recover the scaling exponents commonly observed in other amorphous materials ($\tau=1.3$, $\alpha=1.5$). while in the second the exponents are significantly larger ($\tau=1.7$, $\alpha=2.2$). We provide a quantitative explanation of the experimental results through a model for the depinning of a ferromagnetic domain wall. The present analysis shed light on the unusually high values for the Barkhausen noise exponents measured by Spasojevic et al. [Phys. Rev. E 54 2531 (1996)].Comment: submitted to JSTAT. 11 pages 5 figure

Beyond power laws: Universality in the average avalanche shape

We report the measurement of multivariable scaling functions for the temporal average shape of Barkhausen noise avalanches, and show that they are consistent with the predictions of simple mean-field theories. We bypass the confounding factors of time-retarded interactions (eddy currents) by measuring thin permal- loy films, and bypass thresholding effects and amplifier distortions by applying Wiener deconvolution. We find experimental shapes that are approximately symmetric, and track the evolution of the scaling function. We solve a mean- field theory for the magnetization dynamics and calculate the form of the scaling function in the presence of a demagnetizing field and a finite field ramp-rate, yielding quantitative agreement with the experiment.Comment: 13 pages, 14 figure

Modulation of PKM alternative splicing by PTBP1 promotes gemcitabine resistance in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and incurable disease. Poor prognosis is due to multiple reasons, including acquisition of resistance to gemcitabine, the first-line chemotherapeutic approach. Thus, there is a strong need for novel therapies, targeting more directly the molecular aberrations of this disease. We found that chronic exposure of PDAC cells to gemcitabine selected a subpopulation of cells that are drug-resistant (DR-PDAC cells). Importantly, alternative splicing (AS) of the pyruvate kinase gene (PKM) was differentially modulated in DR-PDAC cells, resulting in promotion of the cancer-related PKM2 isoform, whose high expression also correlated with shorter recurrence-free survival in PDAC patients. Switching PKM splicing by antisense oligonucleotides to favor the alternative PKM1 variant rescued sensitivity of DR-PDAC cells to gemcitabine and cisplatin, suggesting that PKM2 expression is required to withstand drug-induced genotoxic stress. Mechanistically, upregulation of the polypyrimidine-tract binding protein (PTBP1), a key modulator of PKM splicing, correlated with PKM2 expression in DR-PDAC cell lines. PTBP1 was recruited more efficiently to PKM pre-mRNA in DR- than in parental PDAC cells. Accordingly, knockdown of PTBP1 in DR-PDAC cells reduced its recruitment to the PKM pre-mRNA, promoted splicing of the PKM1 variant and abolished drug resistance. Thus, chronic exposure to gemcitabine leads to upregulation of PTBP1 and modulation of PKM AS in PDAC cells, conferring resistance to the drug. These findings point to PKM2 and PTBP1 as new potential therapeutic targets to improve response of PDAC to chemotherapy.Oncogene advance online publication, 3 August 2015; doi:10.1038/onc.2015.270

A stretcher and holder module

Abstract This paper describes the general structure and the performance of a compact module, designed to stretch and hold analog signals up to several hundreds of microseconds, without remarkable changes in the pulse height and shape, and to provide a convenient interface between detector systems and data acquisition equipment

Characterization of two new alleles at the goat CSN1S2 locus.

Two novel alleles at the goat CSN1S2 locus have been identified: CSN1S2(F) and CSN1S2(D). Sequence analyses revealed that the CSN1S2(F) allele is characterized by a G --> A transition at the 13th nucleotide in exon 3 changing the seventh amino acid of the mature protein from Val to Ile. The CSN1S2(D) allele, apparently associated with a decreased synthesis of alpha s2-casein, is characterized by a 106-bp deletion, involving the last 11 bp of the exon 11 and the first 95 bp of the following intron. Methods (PCR-RFLP and PCR) for identification of carriers of these alleles have been developed

Systematic uncertainties in the determination of the local dark matter density

A precise determination of the local dark matter density and an accurate control over the corresponding uncertainties are of paramount importance for Dark Matter (DM) searches. Using very recent high-resolution numerical simulations of a Milky Way like object, we study the systematic uncertainties that affect the determination of the local dark matter density based on dynamical measurements in the Galaxy. In particular, extracting from the simulation with baryons the orientation of the Galactic stellar disk with respect to the DM distribution, we study the DM density for an observer located at $\sim$8 kpc from the Galactic center {\it on the stellar disk}, $\rho_0$. This quantity is found to be always larger than the average density in a spherical shell of same radius $\bar{\rho}_0$, which is the quantity inferred from dynamical measurements in the Galaxy, and to vary in the range $\rho_0/\bar{\rho}_0=1.01-1.41$. This suggests that the actual dark matter density in the solar neighbourhood is on average 21\% larger than the value inferred from most dynamical measurements, and that the associated systematic errors are larger than the statistical errors recently discussed in the literature.Comment: 6 pages, 3 figures, matches published versio

The WIMP Forest: Indirect Detection of a Chiral Square

The spectrum of photons arising from WIMP annihilation carries a detailed imprint of the structure of the dark sector. In particular, loop-level annihilations into a photon and another boson can in principle lead to a series of lines (a WIMP forest) at energies up to the WIMP mass. A specific model which illustrates this feature nicely is a theory of two universal extra dimensions compactified on a chiral square. Aside from the continuum emission, which is a generic prediction of most dark matter candidates, we find a "forest" of prominent annihilation lines that, after convolution with the angular resolution of current experiments, leads to a distinctive (2-bump plus continuum) spectrum, which may be visible in the near future with the Fermi Gamma-Ray Space Telescope (formerly known as GLAST).Comment: 11 pages, 4 figure

MULTI-TEMPORAL IMAGE CO-REGISTRATION OF UAV BLOCKS: A COMPARISON OF DIFFERENT APPROACHES

Abstract. Traditionally, data co-registration of survey epochs in photogrammetry relied on Ground Control Points (GCP) to keep the reference system unchanged. In the last years, Unmanned Aerial Systems (UAV) are increasingly used in photogrammetric environmental monitoring. The diffusion of affordable UAV platforms equipped with GNSS (Global Navigation Satellite System) centimetre-grade receivers might reduce, but not eliminate, the need for GCP. Conversely, if GNSS-assisted orientation cannot be used or if additional ground control and reliability checks are required, alternatives to repeated GCP survey have been proposed, taking advantage of Structure from Motion (SfM) photogrammetry. In particular, co-registering different epochs image blocks together, identifying corresponding features, has been demonstrated as a viable and efficient approach. In this paper four different strategies easily implementable in a generic commercial photogrammetric software are presented and compared considering three different test sites in Italy subject to different amounts of environmental changes. The influence of the amount and distribution of inter-epoch corresponding points on the accuracy of the reconstruction is investigated. The results show that some of the tested strategies obtains very good results and can be used (although not needed) also in RTK centimetre-grade UAV surveys, leveraging the additional information coming from previous epochs survey to actually increase the survey accuracy and reliability

SEEDS - THE INTERNATIONAL MASTER PROGRAM FOR PREPARING THE YOUNG SYSTEMS ENGINEERS FOR SPACE EXPLORATION

The SEEDS initiative originated by Politecnico di Torino and Thales Alenia Space Italy in 2005. It aimed at establishing a Post Graduate International Master Course in Space Exploration and Development Systems "SEEDS", to offer an opportunity to young engineers to get prepared for the future of Europe in space exploration. The SEEDS project has been shared with Supaero Toulouse in France and with University at Bremen (together with ZARM) in Germany, as the three European towns (Torino, Toulouse and Bremen) have a long common tradition of space activities at both the industrial and academic level and represent three poles of the European cooperation in space programs. The SEEDS course comprises two different steps in sequence: an initial Learning Phase and a Project Work Phase. Both the Learning and the Project Work Phase pursue a multidisciplinary approach, where all specialized disciplines are blended together and integrated to enable the students to acquire the system view and then to accomplish the conceptual design, through the Systems Engineering approach, of a selected case-study. The distinguishing feature of SEEDS is without any doubt the Project Work activity, performed by all students together under the supervision of academic and industrial Tutors, coordinated by the Education Project Manager. Main objective of the Project Work is to train the students on the basic principles of the System Engineering Design, through their application on a well defined project related to a specific space exploration mission. The Project Work includes the Preparatory Work, during which the students, starting from the definition of the mission statement, focus on the identification of the complete architecture of the space exploration mission, and the Conceptual Design activities, performed in the three European sites to develop a limited number of building blocks identified during the Preparatory Work. The first year of activity started in November 2005, with a Plenary Opening which took place at the ESA-ERASMUS Centre, Noordwijk, with the full support of the Human Space-Flight Microgravity and Exploration Directorate of ESA. Five years of activities have passed since then and five project works have been successfully completed, dealing with various space exploration themes. This paper focuses on the description of the SEEDS course and on the main results achieved in terms of project work activities and development of the future space workforce. The positive experience of five years of SEEDS is brought to evidence and the lessons learned are discussed in view of the SEEDS continuatio

Parallel symbolic state-space exploration is difficult, but what is the alternative?

State-space exploration is an essential step in many modeling and analysis problems. Its goal is to find the states reachable from the initial state of a discrete-state model described. The state space can used to answer important questions, e.g., "Is there a dead state?" and "Can N become negative?", or as a starting point for sophisticated investigations expressed in temporal logic. Unfortunately, the state space is often so large that ordinary explicit data structures and sequential algorithms cannot cope, prompting the exploration of (1) parallel approaches using multiple processors, from simple workstation networks to shared-memory supercomputers, to satisfy large memory and runtime requirements and (2) symbolic approaches using decision diagrams to encode the large structured sets and relations manipulated during state-space generation. Both approaches have merits and limitations. Parallel explicit state-space generation is challenging, but almost linear speedup can be achieved; however, the analysis is ultimately limited by the memory and processors available. Symbolic methods are a heuristic that can efficiently encode many, but not all, functions over a structured and exponentially large domain; here the pitfalls are subtler: their performance varies widely depending on the class of decision diagram chosen, the state variable order, and obscure algorithmic parameters. As symbolic approaches are often much more efficient than explicit ones for many practical models, we argue for the need to parallelize symbolic state-space generation algorithms, so that we can realize the advantage of both approaches. This is a challenging endeavor, as the most efficient symbolic algorithm, Saturation, is inherently sequential. We conclude by discussing challenges, efforts, and promising directions toward this goal