The Nature of the Peculiar Virgo Cluster Galaxies NGC 4064 and NGC 4424

We present a detailed study of the peculiar HI-deficient Virgo cluster spiral galaxies NGC 4064 and NGC 4424, using $^{12}$CO 1-0 interferometry, optical imaging and integral-field spectroscopic observations, in order to learn what type of environmental interactions have afected these galaxies. Optical imaging reveals that NGC 4424 has a strongly disturbed stellar disk, with banana-shaped isophotes and shells. NGC 4064, which lies in the cluster outskirts, possesses a relatively undisturbed outer stellar disk and a central bar. In both galaxies H-alpha emission is confined to the central kiloparsec. CO observations reveal bilobal molecular gas morphologies, with H-alpha emission peaking inside the CO lobes, implying a time sequence in the star formation process.Gas kinematics reveals strong bar-like non-circular motions in the molecular gas in both galaxies, suggesting that the material is radially infalling. In NGC 4064 the stellar kinematics reveal strong bar-like non-circular motions in the central 1 kpc. On the other hand, NGC 4424 has extremely modest stellar rotation velocities (Vmax ~ 30 km s-1), and stars are supported by random motions as far out as we can measure it. The observations suggest that the peculiarities of NGC 4424 are the result of an intermediate-mass merger plus ram pressure stripping. In the case of NGC 4064, the evidence suggests an already stripped "truncated/normal" galaxy that recently suffered a minor merger or tidal interaction with another galaxy. We propose that galaxies with "truncated/compact" H-alpha morphologies such as these are the result of the independent effects of ram pressure stripping, which removes gas from the outer disk, and gravitational interactions such as mergers, which heat stellar disks, drive gas to the central kpc and increase the central mass concentrations.Comment: 42 pages, 21 figure

Asociación entre Trastornos Óseos Degenerativos y Acumulación de Líquido en los Recesos de la Articulación Temporomandibular

ResumenEl Objetivo del presente estudio fue determinar la asociación entre presencia de líquido intra-articular y alteraciones degenerativas en las ATM de pacientes adultos con diagnóstico clínico de Trastornos Temporomandibulares, por medio de diagnóstico imagenológico, antes de iniciar su tratamiento.Material y MétodoSe reclutaron 135 pacientes consecutivos (promedio de edad = 33,3 años) que clínicamente presentan disfunciones de las ATM y que fueron examinados por medio de Resonancia Magnética (RM) y Tomografía Computada (TC). Los criterios de exclusión fueron: pacientes menores de 16 años, pacientes mayores de 65 años, pacientes portadores de prótesis dentarias removibles, con enfermedades sistémicas como gota, Osteoartrosis sistémica, hiperlaxitud ligamentaria, malformaciones anatómicas, enfermedades quísticas, tumorales, historia de trauma o cirugía de las ATM. Todos los pacientes fueron examinados utilizando el resonador magnético [Phillips Intera 1,5 T, bobina Sense Flex S Dual] en las secuencias; sagital DP-T2-Spir, coronal DP y dinámico ECHO gradiente y también fueron examinados por medio de Tomografía Computada (TC), con cortes de volúmenes-axiales y volúmenes-coronales de 625um de espesor [BrightSpeed®ELITE, General Electric, Milwaukee, USA)] tanto a boca abierta como cerrada, bajo los siguientes parámetros: FOV: 16.0cms, Algoritmo Hueso, Filtro Edge A2 y Matriz 512x512 pxs]. Los estudios imagenológicos de las ATMs formaron los siguientes ocho grupos: Grupo A: Ausencia de líquido (L) en ATM Derecha con Alteración Degenerativa (AD); Grupo B: Presencia de Líquido en ATM Derecha con AD; Grupo C: Ausencia de Líquido en ATM Izquierda con AD; Grupo D: Presencia de L en ATM Izquierda con AD; Grupo E: Ausencia de AD y Ausencia de L en ATM Derecha; Grupo F: Ausencia de AD y Presencia de L en ATM Derecha; Grupo G: Ausencia de L en ATM Izquierda; Grupo H: Presencia de L y ausencia de AD en ATM Izquierda. Los datos fueron analizados estadísticamente con la prueba Chi2 (Systat v12.0).ResultadoGrupo A: n= 61; Grupo B: n= 64; Grupo C: n= 54; Grupo D: n= 53; Grupo E; n=12; Grupo F; n=13; Grupo G: n=8 y Grupo H: n=5.ConclusiónNo existe asociación entre la presencia de líquido intra-articular y Alteraciones Degenerativas de las superficies articulares en la ATM.AbstractThe Objective of the present study was to determine the association between articular space effusion and degenerative bone disease in adult TMJ with internal derangement, previous any treatment, by images diagnosis.Materials y MethodsWere recruited 135 consecutives patients (X=33.3 years) that presented TMJ dysfunction were examined using Magnetic Resonance (MRI) [Phillips Intera 1,5 T, Sense Flex S Dual Coil] in sequences; sagital DP-T2-Spir, coronal DP and dynamic ECHO gradient and using Computed Tomography (TC) by axial-volumes slices and coronal-volumes slices of 625um of width [BrightSpeed®ELITE, General Electric, Milwaukee, USA], with the patient in open mouth and closed mouth under the next parameters: FOV: 16.0cms, Bone Algorithm, Edge Filter A2 and Matrix 512x512 pxs. The exclusion criteria was: patients below 16 years and above 65 years of age, patients using removable dental prosthetics, patients that presented systemic disease such as Gout Disease, Osteoarthrosis and hipermobility, anatomic structural alterations, Quistic or Tumor disease and TMJ surgery. The TMJ images studies formed the following eight groups: Group A: Absence of effusion (L) in right TMJ with Degenerative Disease (AD); Group B: Presence of L in right TMJ with AD; Grupo C: Absence of L in left TMJ with AD; Group D: Presence of L in left TMJ with AD; Group E: Absence of AD and absence of L in right TMJ; Group F: Absence of AD and presence of L in right TMJ; Group G: Absence of L in left TMJ; Group H: Presence of L and absence of AD in left TMJ. Data were statistically analyzed by Chi2 (Systat v12.0).ResultsGroup A: n= 61; Group B: n= 64; Group C: n= 54; Group D: n= 53; Group E; n=12; Group F; n=13; Group G: n=8 y Group H: n=5.ConclusionNo association was found between Degenerative Bone Disease and Temporo mandibular Joint Articular Space Effusion in TMJ

ATRA mechanically reprograms pancreatic stellate cells to suppress matrix remodelling and inhibit cancer cell invasion

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a dismal survival rate. Persistent activation of pancreatic stellate cells (PSCs) can perturb the biomechanical homoeostasis of the tumour microenvironment to favour cancer cell invasion. Here we report that ATRA, an active metabolite of vitamin A, restores mechanical quiescence in PSCs via a mechanism involving a retinoic acid receptor beta (RAR-β)-dependent downregulation of actomyosin (MLC-2) contractility. We show that ATRA reduces the ability of PSCs to generate high traction forces and adapt to extracellular mechanical cues (mechanosensing), as well as suppresses force-mediated extracellular matrix remodelling to inhibit local cancer cell invasion in 3D organotypic models. Our findings implicate a RAR-β/MLC-2 pathway in peritumoural stromal remodelling and mechanosensory-driven activation of PSCs, and further suggest that mechanical reprogramming of PSCs with retinoic acid derivatives might be a viable alternative to stromal ablation strategies for the treatment of PDAC

On Security and Sparsity of Linear Classifiers for Adversarial Settings

Machine-learning techniques are widely used in security-related applications, like spam and malware detection. However, in such settings, they have been shown to be vulnerable to adversarial attacks, including the deliberate manipulation of data at test time to evade detection. In this work, we focus on the vulnerability of linear classifiers to evasion attacks. This can be considered a relevant problem, as linear classifiers have been increasingly used in embedded systems and mobile devices for their low processing time and memory requirements. We exploit recent findings in robust optimization to investigate the link between regularization and security of linear classifiers, depending on the type of attack. We also analyze the relationship between the sparsity of feature weights, which is desirable for reducing processing cost, and the security of linear classifiers. We further propose a novel octagonal regularizer that allows us to achieve a proper trade-off between them. Finally, we empirically show how this regularizer can improve classifier security and sparsity in real-world application examples including spam and malware detection

Generating, probing and utilising photo-induced surface oxygen vacancies for trace molecular detection

Metal oxide semiconductors (MOS) are extensively used for a wide range of industrial applications [1] – [3] , where defects states in MOS can strongly affect their overall performance, even at very low concentrations [4] , [5] . The functionality of MOS has been reported to be significantly altered through the addition of defects, whereby the materials can become more/less chemically active or the electronic properties are altered. Surface defects, in particular, are often one of the most reactive sites on the surface, greatly influencing MOS photocatalytic activity. Under UV irradiation conditions, interactions with photo- induced charge carriers can generate temporary oxygen vacancies, VO, defect states on the surface of MOS [6] , affecting the material properties during the defects’ lifetime

Unstable Dynamics, Nonequilibrium Phases and Criticality in Networked Excitable Media

Here we numerically study a model of excitable media, namely, a network with occasionally quiet nodes and connection weights that vary with activity on a short-time scale. Even in the absence of stimuli, this exhibits unstable dynamics, nonequilibrium phases -including one in which the global activity wanders irregularly among attractors- and 1/f noise while the system falls into the most irregular behavior. A net result is resilience which results in an efficient search in the model attractors space that can explain the origin of certain phenomenology in neural, genetic and ill-condensed matter systems. By extensive computer simulation we also address a relation previously conjectured between observed power-law distributions and the occurrence of a "critical state" during functionality of (e.g.) cortical networks, and describe the precise nature of such criticality in the model.Comment: 18 pages, 9 figure

Hysteresis and bi-stability by an interplay of calcium oscillations and action potential firing

Many cell types exhibit oscillatory activity, such as repetitive action potential firing due to the Hodgkin-Huxley dynamics of ion channels in the cell membrane or reveal intracellular inositol triphosphate (IP$_3$) mediated calcium oscillations (CaOs) by calcium-induced calcium release channels (IP$_3$-receptor) in the membrane of the endoplasmic reticulum (ER). The dynamics of the excitable membrane and that of the IP$_3$-mediated CaOs have been the subject of many studies. However, the interaction between the excitable cell membrane and IP$_3$-mediated CaOs, which are coupled by cytosolic calcium which affects the dynamics of both, has not been studied. This study for the first time applied stability analysis to investigate the dynamic behavior of a model, which includes both an excitable membrane and an intracellular IP$_3$-mediated calcium oscillator. Taking the IP$_3$ concentration as a control parameter, the model exhibits a novel rich spectrum of stable and unstable states with hysteresis. The four stable states of the model correspond in detail to previously reported growth-state dependent states of the membrane potential of normal rat kidney fibroblasts in cell culture. The hysteresis is most pronounced for experimentally observed parameter values of the model, suggesting a functional importance of hysteresis. This study shows that the four growth-dependent cell states may not reflect the behavior of cells that have differentiated into different cell types with different properties, but simply reflect four different states of a single cell type, that is characterized by a single model.Comment: 29 pages, 6 figure

PAC-Bayesian Bounds for Randomized Empirical Risk Minimizers

The aim of this paper is to generalize the PAC-Bayesian theorems proved by Catoni in the classification setting to more general problems of statistical inference. We show how to control the deviations of the risk of randomized estimators. A particular attention is paid to randomized estimators drawn in a small neighborhood of classical estimators, whose study leads to control the risk of the latter. These results allow to bound the risk of very general estimation procedures, as well as to perform model selection

BPS black holes, quantum attractor flows and automorphic forms

We propose a program for counting microstates of four-dimensional BPS black holes in N >= 2 supergravities with symmetric-space valued scalars by exploiting the symmetries of timelike reduction to three dimensions. Inspired by the equivalence between the four dimensional attractor flow and geodesic flow on the three-dimensional scalar manifold, we radially quantize stationary, spherically symmetric BPS geometries. Connections between the topological string amplitude, attractor wave function, the Ooguri-Strominger-Vafa conjecture and the theory of automorphic forms suggest that black hole degeneracies are counted by Fourier coefficients of modular forms for the three-dimensional U-duality group, associated to special "unipotent" representations which appear in the supersymmetric Hilbert space of the quantum attractor flow.Comment: 9 pages, revtex; v2: references added and typos correcte