Characterization of the Hamamatsu R11410-10 3-Inch Photomultiplier Tube for Liquid Xenon Dark Matter Direct Detection Experiments

To satisfy the requirements of the next generation of dark matter detectors based on the dual phase TPC, Hamamatsu, in close collaboration with UCLA, has developed the R11410-10 photomultipler tube. In this work, we present the detailed tests performed on this device. High QE (>30%) accompanied by a low dark count rate (50 Hz at 0.3 PE) and high gain (10^7) with good single PE resolution have been observed. A comprehensive screening measurement campaign is ongoing while the manufacturer quotes a radioactivity of 20 mBq/PMT. These characteristics show the R11410-10 to be particularly suitable for the forthcoming zero background liquid xenon detectors.Comment: 19 pages, 18 figure

Depinning of three-dimensional drops from wettability defects

Substrate defects crucially influence the onset of sliding drop motion under lateral driving. A finite force is necessary to overcome the pinning influence even of microscale heterogeneities. The depinning dynamics of three-dimensional drops is studied for hydrophilic and hydrophobic wettability defects using a long-wave evolution equation for the film thickness profile. It is found that the nature of the depinning transition explains the experimentally observed stick-slip motion.Comment: 6 pages, 9 figures, submitted to ep

Expected Sensitivity to Galactic/Solar Axions and Bosonic Super-WIMPs based on the Axio-electric Effect in Liquid Xenon Dark Matter Detectors

We present systematic case studies to investigate the sensitivity of axion searches by liquid xenon detectors, using the axio-electric effect (analogue of the photoelectric effect) on xenon atoms. Liquid xenon is widely considered to be one of the best target media for detection of WIMPs (Weakly Interacting Massive Particles which may form the galactic dark matter) using nuclear recoils. Since these detectors also provide an extremely low radioactivity environment for electron recoils, very weakly-interacting low-mass particles (< 100 keV/c^2), such as the hypothetical axion, could be detected as well - in this case using the axio-electric effect. Future ton-scale liquid Xe detectors will be limited in sensitivity only by irreducible neutrino background (pp-chain solar neutrino and the double beta decay of 136Xe) in the mass range between 1 and 100 keV/c^2. Assuming one ton-year of exposure, galactic axions (as non-relativistic dark matter) could be detected if the axio-electric coupling g_Ae is greater than 10^-14 at 1 keV/c^2 (or $10^-13 at 100 keV/c^2). Below a few keV/c^2, and independent of the mass, a solar axion search would be sensitive to a coupling g_Ae ~ 10^-12. This limit will set a stringent upper bound on axion mass for the DFSV and KSVZ models for the mass ranges m_A < 0.1 eV/c^2 and < 10 eV/c^2, respectively. Vector-boson dark matter could also be detected for a coupling constant alpha'/alpha > 10^-33 (for mass 1 keV/c^2) or > 10^-27 (for mass 100 keV/c^2).Comment: 17 pages, 10 figure

Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

In the present contribution we review basic mathematical results for three physical systems involving self-organising solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e., time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different system. First, we discuss the linear stability of homogeneous steady states, i.e., flat films; and second the systematics of non-trivial steady states, i.e., drop/hole states for dewetting films and quantum dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing to the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly not related physical systems mathematically, but does as well allow to discuss model extensions in a more unified way

Rayleigh and depinning instabilities of forced liquid ridges on heterogeneous substrates

Depinning of two-dimensional liquid ridges and three-dimensional drops on an inclined substrate is studied within the lubrication approximation. The structures are pinned to wetting heterogeneities arising from variations of the strength of the short-range polar contribution to the disjoining pressure. The case of a periodic array of hydrophobic stripes transverse to the slope is studied in detail using a combination of direct numerical simulation and branch-following techniques. Under appropriate conditions the ridges may either depin and slide downslope as the slope is increased, or first breakup into drops via a transverse instability, prior to depinning. The different transition scenarios are examined together with the stability properties of the different possible states of the system.Comment: Physics synopsis link: http://physics.aps.org/synopsis-for/10.1103/PhysRevE.83.01630

Sampling sufficiency for mechanical properties of wood

Based on most recently published studies, there is a large variability in both the mechanical properties of wood and sample sizes selected to evaluate them. This study aims to define sampling sufficiency for some mechanical properties of wood, which were bending strength, bending modulus, compressive strength, compressive modulus, hardness, and shear strength. The mechanical tests were carried out according to the ASTM D143 on wood samples cut from clonal Eucalyptus planted in southern Brazil. Sampling sufficiency was determined by an intensive computational method based on resampling of original data using Monte Carlo simulations. The experimental tests data conformed to the normal distribution and most of the obtained sufficient sample sizes determined by Monte Carlo simulation were above those sample sizes used in most already published studies. Furthermore, properties related to wood stiffness presented smaller variabilities than their respective properties associated with wood strength, leading to smaller sample sizes for the former cases

GERMINAÇÃO, MORFOLOGIA E ANÁLISE DA DISTRIBUIÇÃO ESPACIAL DA QUALIDADE FISIOLÓGICA DE SEMENTES DE Joannesia princeps VELL

BELTRAME, Rômulo André. Germinação, morfologia e análise da distribuição espacial da qualidade fisiológica de sementes de Joannesia princeps Vell. 2013. Dissertação (Mestrado em Ciências Florestais) Universidade Federal do Espírito Santo, Alegre-ES. Orientador: Prof. Dr. José Carlos Lopes. Coorientadores: Prof. Dr. Julião Soares de Souza Lima e Profª. Dra. Tatiana Tavares Carrijo. O sucesso na fase de produção de mudas de espécies florestais esta diretamente relacionado com a qualidade fisiológica das sementes utilizadas. O presente trabalho teve como objetivo obter informações sobre a propagação da cutieira (Joannesia princeps) e da qualidade fisiológica de suas sementes, além de estudar aspectos morfológicos e biométricos dos frutos, sementes e plântulas. Inicialmente, objetivou-se avaliar tratamentos físicos, químicos e níveis de sombreamento na emergência e desenvolvimento inicial das plântulas. Sementes intactas (T1) e com o tegumento trincado (T2) foram avaliadas quanto à absorção de água. As sementes foram submetidas a tratamentos pré-germinativos: (T1) semente intacta (testemunha), (T2) tegumento trincado, (T3) tegumento removido, (T4) imersão em ácido sulfúrico (95%) por 5 minutos, (T5) imersão em ácido sulfúrico (95%) por 10 minutos e (T6) imersão em ácido sulfúrico (95%) por 15 minutos. Posteriormente, avaliou-se a relação entre tratamentos de embebição com GA3 em diferentes tempos (zero, seis, 12 e 24 h), e níveis de sombreamento (sol pleno, sombreamento com uma e duas telas) na emergência e desenvolvimento de plântulas. Avaliou-se: emergência, índice de velocidade de emergência, comprimento da parte aérea e do sistema radicular, diâmetro do coleto, massa fresca e seca da parte aérea e do sistema radicular. Ainda, aspectos morfológicos e biométricos de frutos, sementes e plântulas foram estudados. Nos frutos foram avaliados os atributos qualitativos em relação à morfologia externa. A análise biométrica teve como base a tomada das dimensões do comprimento, diâmetro e espessura. As sementes foram avaliadas em relação à morfologia externa e interna. As avaliações das plântulas foram conduzidas periodicamente no sexto, sétimo, 14º, 21º, 28º, 35º e 42º dia. Utilizaram-se 15 plântulas normais e sadias para as descrições. Por fim, objetivou-se estudar e analisar a distribuição espacial dos atributos que determinam a qualidade fisiológica de sementes de Joannesia princeps. As sementes foram coletadas, individualmente, de 40 árvores matrizes no Horto Municipal de Alegre-ES e o experimento conduzido em casa de vegetação do Departamento de Produção Vegetal do CCAUFES. As sementes tiveram o tegumento trincado e foi realizada a embebição em ácido giberélico GA3 500 mgL-1 durante 24 h em câmara tipo BOD com temperatura ajustada para 30 ºC. A semeadura foi realizada em sacos plásticos de ±600 cm3 contendo terra+areia+esterco na proporção de 1:1:1. Foram avaliados os seguintes atributos: emergência (E), índice de velocidade de emergência (IVE), comprimento da raiz (CR), diâmetro do coleto (DC), comprimento da parte aérea (CPA), massa fresca do sistema radicular (MFSR), massa fresca da parte aérea (MFPA), massa seca do sistema radicular (MSSR) e massa seca da parte aérea (MSPA). Maiores valores de emergência são obtidos em sementes intactas (30%) e sementes trincadas (33%). A germinação é estimulada pelo GA3, atingindo 97% de emergência na imersão por 24 horas, no sombreamento com duas telas. Os maiores valores do IQD foram obtidos em sol pleno e os menores no sombreamento com duas telas. Observou-se que as raízes mudaram o tom de sua coloração de esbranquiçada para branco-amarelada do 14º para o 21º dia após a semeadura. O hipocótilo, nos estádios iniciais apresenta coloração avermelhada passando para verde após o 14º dia transcorrido da semeadura. Os demais órgãos não apresentaram mudanças consideráveis. No entanto, biometricamente, todos os órgãos apresentaram um acréscimo nas suas dimensões, conforme a evolução do desenvolvimento. Com exceção do CPA, verificou-se dependência espacial para as demais variáveis estudadas: E, IVE, CR, DC, MFSR, MFPA, MSSR e MSPA; com alcance variando de 6,10 a 48,67 m, sendo o menor alcance e maior IDE obtidos para a MFSR; maior alcance para a MSSR e menor IDE para o IVE. Palavras-chave: Joannesia princeps, sementes, morfologia, qualidade fisiológica, distribuição espacial

Histological analysis of ACL reconstruction failures due to synthetic-ACL (LARS) ruptures

INTRODUCTION: Anterior Cruciate Ligament (ACL) reconstruction is an established surgical procedure. Synthetic ligaments represent an option for ACL reconstruction. Their popularity declined for the raising concerns due to re-ruptures, knee synovitis and early arthritis related to I and II generation artificial ligaments. The introduction of a III generation synthetic ligament (Ligament Advanced Reinforcement System-LARS) permitted renewed interest in the adoption of this kind of graft. Main purpose of our study was to describe the histological findings on samples obtained from a consecutive series of ACL revision surgeries due to LARS ACL reconstruction failures. Secondary aim was to determine the reason for LARS rupture. METHODS: In a period between 2016 and 2018 eleven patients underwent ACL revision surgery due to LARS ACL reconstruction failure. At the time of the arthroscopic procedure, samples of synovial membrane and remnants of the torn LARS were sent to the Pathological-Anatomy Institute of our Hospital for a histological analysis. RESULTS: Histological analysis of the synovial tissues confirmed the arthroscopic evidence of synovitis mainly characterized by chronic inflammation with predominance of multinucleated giant cells. The adoption of polarized light microscopy revealed the presence of brightly bi-refractive material (LARS wear particles) in the synovial tissue; at higher magnification wear debris were detected inside the cytoplasma of multi nucleated cells. The histological analysis of the removed LARS revealed a surrounding typical foreign body reaction with poor signs of fibrovascular ingrowth of the synthetic ligament. CONCLUSIONS: Our findings could not clearly advocate a unique mechanism of LARS-ACL reconstruction failure: biologic issues (poor tissue ingrowth) and mechanical issues (fibers properties and tunnel position) probably concur in a multi factorial manner. ACL reconstruction using artificial ligaments can not be considered a simple surgery. Artificial augments require some expertise and could therefore achieve better results if used by skilled sport surgeons other than trainees or low volume surgeons. The Authors believe that ACL reconstruction with synthetic devices still have restricted indications for selected patients (e.g. elderly patients who require a fast recovery, professional athlete, autologous tendons not available and/or refusing donor tendons). Our study arises additional suspicion on the unresponsiveness of synthetic fibers and claim some concern in the implantation of synthetic devices

Unsupervised activity recognition for autonomous water drones

We propose an automatic system aimed at discovering relevant activities for aquatic drones employed in water monitoring applications. The methodology exploits unsupervised time series segmentation to pursue two main goals: i) to support on-line decision making of drones and operators, ii) to support off-line analysis of large datasets collected by drones. The main novelty of our approach consists of its unsupervised nature, which enables to analyze unlabeled data. We investigate different variants of the proposed approach and validate them using an annotated dataset having labels for activity \u201cupstream/downstream navigation\u201d. Obtained results are encouraging in terms of clustering purity and silhouette which reach values greater than 0.94 and 0.20, respectively, in the best models

Human resilience to Holocene climate changes inferred from rodent middens in drylands of northwestern Patagonia (Argentina)

We reconstruct the Holocene vegetation, climate, and archaeological history for drylands of northwestern Patagonia, Argentina, based on multiproxy analysis (plant macrofossil, pollen, and parasites) of rodent middens integrated with a database of {14}^C dates associated with human occupations. The local scale corresponds to the Huenul paleoecological and archaeological locality, emplaced in north-western Patagonia (Neuquén Province, Argentina). The rodent midden record from the Huenul series reflects subtle vegetation changes driven by climatic variability at millennial timescale. Drier than present environmental conditions prevailed during the early Holocene (10,500–9400 cal yr BP), peaking during the mid-Holocene (9200–5500 cal yr BP), when wetter than present conditions established during the late Holocene (4400–2500 cal yr BP). These environmental and climatic dynamics agree with other paleoclimatic records from northern Patagonia, suggesting the winter precipitation dynamics related to the Southern Westerlies as a common driver. The diachronic distribution of anthropogenic radiocarbon dates from the western area of the South American Arid Diagonal between 32°–40°S conforms to a fitted exponential model of steady background population growth, not suggesting significant demographic changes that may have been the result of the impact of climate change. This record indicates that these human populations coped successfully with aridity, particularly during the mid-Holocene. These findings reinforce the need to integrate multi-scalar interdisciplinary analyses to assess the impact of climate change in human societies