1,601 research outputs found
Progress in Theoretical and Numerical Tools Devoted to Understanding of Acoustic Devices Behavior
Computing labs and Technology Classroom (ClTC) Initiative: A Model for Distributed Support
DePauw University is a small, liberal arts institution with 2200 undergraduate residential students and 222 faculty members, located in Greencastle, Indiana The challenges of supporting a campus with multiple and diverse facilities are further amplified by limited staff support resources. One of the strategies for addressing these challenges led to the formation of the Computing Labs and Technology Classrooms (CLTC) initiative. The CLTC recognizes and draws on the strengths of support specialists with a wide variety of professional training and experience, who regularly collaborate in the support and management of campus-wide labs and technology classrooms
A prova de exercício cárdio-pulmonar e o prognóstico cirúrgico do cancro do pulmão
Resumo: Os autores procuram dar mais um contributo para a avaliação pré-operatória dos doentes com carcinoma de não pequenas células que vão ser sujeitos a cirurgia de ressecção pulmonar.Trata-se de um estudo prospectivo onde foi avaliado o resultado da cirurgia em termos de complicações ocorridas nos 30 dias a seguir à operação. Os autores definiram cada uma das complicações (óbito, enfarte do miocárdio, insuficiências respiratória, cardÃaca e renal, embolia pulmonar, pneumonia e septicemia) e ainda analisaram 3 dessas complicações em separado (óbito, enfarte do miocárdio e insuficiência respiratória), as quais designaram por âfraco resultadoâ.Antes da cirurgia, foram avaliados 99 doentes (34 pneumectomias, 56 lobectomias, 6 bilobectomias e 3 ressecções atÃpicas) com espirometria (FEV1 em litros) e consumo de oxigénio no exercÃcio máximo (VO2peak). Só 26 doentes tinham valores funcionais considerados borderline (FEV1 < 1,5 litros para lobectomia e < 2,0 litros para pneumectomia). Nos resultados apresentados observámos os seguintes valores médios: FEV1=2,06 litros; FEV1=80,4% do valor teórico; VO2peak=18,8 ml/kg/min ou 88,3% do valor teórico. Só existiram 4 óbitos (4%) e 21 doentes tiveram uma ou mais das complicações referenciadas.Os autores não encontraram relação significativa entre as complicações pós-operatórias e o FEV1 em litros. Verificaram ainda que o VO2peak em percentagem do valor teórico previa melhor um âfraco resultadoâ do que o mesmo parâmetro em valor absoluto.Em relação aos óbitos, um dos doentes tinha sido submetido a quimioterapia, o que dificultou a avaliação do desfecho. Nos restantes 3 óbitos, todos os doentes tinham um VO2peak < 62% do valor teórico. Dois dos 3 doentes com VO2peak < 50% tiveram um âfraco resultadoâ. Com VO2peak > 75% só 3 em 20 doentes é que tiveram um âfraco resultadoâ.Apesar de reconhecerem a necessidade de mais e maiores estudos, os autores concluem que VO2peak é importante para prever complicações como óbito, enfarte do miocárdio ou insuficiência respiratória, principalmente se é referido em percentagem do valor teórico. O limite âseguroâ situar-se-ia entre 50 e 60% do valor previsto
Synaptic Depression of the Hyppocampal to Prefrontal Cortex Pathway during a Spatial Working Memory Task
Convective Motion in a Vibrated Granular Layer
Experimental results are presented for a vertically shaken granular layer. In
the range of accelerations explored, the layer develops a convective motion in
the form of one or more rolls. The velocity of the grains near the wall has
been measured. It grows linearly with the acceleration, then the growing rate
slows down. A rescaling with the amplitude of the wall velocity and the height
of the granular layer makes all data collapse in a single curve. This can
provide insights on the mechanism driving the motion.Comment: 10 pages, 5 figures submitted to Phys. Rev. Let
Observation of Sommerfeld precursors on a fluid surface
We report the observation of two types of Sommerfeld precursors (or
forerunners) on the surface of a layer of mercury. When the fluid depth
increases, we observe a transition between these two precursor surface waves in
good agreement with the predictions of asymptotic analysis. At depths thin
enough compared to the capillary length, high frequency precursors propagate
ahead of the ''main signal'' and their period and amplitude, measured at a
fixed point, increase in time. For larger depths, low frequency ''precursors''
follow the main signal with decreasing period and amplitude. These behaviors
are understood in the framework of the analysis first introduced for linear
transient electromagnetic waves in a dielectric medium by Sommerfeld and
Brillouin [1].Comment: to be published in Physical Review Letter
Broadband microwave spectroscopy of semiconductor nanowire-based Cooper-pair transistors
The Cooper-pair transistor (CPT), a small superconducting island enclosed
between two Josephson weak links, is the atomic building block of various
superconducting quantum circuits. Utilizing gate-tunable semiconductor channels
as weak links, the energy scale associated with the Josephson tunneling can be
changed with respect to the charging energy of the island, tuning the extent of
its charge fluctuations. Here, we directly demonstrate this control by mapping
the energy level structure of a CPT made of an indium arsenide nanowire (NW)
with a superconducting aluminum shell. We extract the device parameters based
on the exhaustive modeling of the quantum dynamics of the phase-biased nanowire
CPT and directly measure the even-odd parity occupation ratio as a function of
the device temperature, relevant for superconducting and prospective
topological qubits.Comment: Published version. Supplementary Information is available as
ancillary file, raw data and calculations can be downloaded from
http://doi.org/10.4121/uuid:5d54f11b-6774-4ae4-96cf-25e6a91927e
Effects of electromagnetic waves on the electrical properties of contacts between grains
A DC electrical current is injected through a chain of metallic beads. The
electrical resistances of each bead-bead contacts are measured. At low current,
the distribution of these resistances is large and log-normal. At high enough
current, the resistance distribution becomes sharp and Gaussian due to the
creation of microweldings between some beads. The action of nearby
electromagnetic waves (sparks) on the electrical conductivity of the chain is
also studied. The spark effect is to lower the resistance values of the more
resistive contacts, the best conductive ones remaining unaffected by the spark
production. The spark is able to induce through the chain a current enough to
create microweldings between some beads. This explains why the electrical
resistance of a granular medium is so sensitive to the electromagnetic waves
produced in its vicinity.Comment: 4 pages, 5 figure
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