13,044 research outputs found
Fiber-diffraction Interferometer using Coherent Fiber Optic Taper
We present a fiber-diffraction interferometer using a coherent fiber optic
taper for optical testing in an uncontrolled environment. We use a coherent
fiber optic taper and a single-mode fiber having thermally-expanded core. Part
of the measurement wave coming from a test target is condensed through a fiber
optic taper and spatially filtered from a single-mode fiber to be reference
wave. Vibration of the cavity between the target and the interferometer probe
is common to both reference and measurement waves, thus the interference fringe
is stabilized in an optical way. Generation of the reference wave is stable
even with the target movement. Focus shift of the input measurement wave is
desensitized by a coherent fiber optic taper
Histopathologic alterations associated with the transplanted homologous dog liver
Homotransplanted livers in dogs developed mononuclear, lymphocytic and plasmacytic infiltration and hepatic cell degeneration roughly paralleling survival time. Extensive histologic alterations of host reticuloendothelial structures occurred. Proliferation and infiltration of mononuclear cells, principally plasmacytes, were noted in lung, kidney, perirenal supportive tissue, bone marrow, and lymph nodes. Lymph nodes, in addition, were characterized by cortical and follicular depletion. These changes were considered to represent extensive host reticuloendothelial mobilization coincident to liver homotransplant rejection. The relation between these alterations and those found in other hypersensitivity states is discussed. © 1962
Synthesis, Structure and Properties of Tetragonal Sr2M3As2O2 (M3 = Mn3, Mn2Cu and MnZn2) Compounds Containing Alternating CuO2-Type and FeAs-Type Layers
Polycrystalline samples of Sr2Mn2CuAs2O2, Sr2Mn3As2O2, and Sr2Zn2MnAs2O2 were
synthesized. Their temperature- and applied magnetic field-dependent
structural, transport, thermal, and magnetic properties were characterized by
means of x-ray and neutron diffraction, electrical resistivity rho, heat
capacity, magnetization and magnetic susceptibility measurements. These
compounds have a body-centered-tetragonal crystal structure (space group
I4/mmm) that consists of MO2 (M = Zn and/or Mn) oxide layers similar to the
CuO2 layers in high superconducting transition temperature Tc cuprate
superconductors, and intermetallic MAs (M = Cu and/or Mn) layers similar to the
FeAs layers in high-Tc pnictides. These two types of layers alternate along the
crystallographic c-axis and are separated by Sr atoms. The site occupancies of
Mn, Cu and Zn were studied using Rietveld refinements of x-ray and neutron
powder diffraction data. The temperature dependences of rho suggest metallic
character for Sr2Mn2CuAs2O2 and semiconducting character for Sr2Mn3As2O2 and
Sr2Zn2MnAs2O2. Sr2Mn2CuAs2O2 is inferred to be a ferrimagnet with a Curie
temperature TC = 95(1) K. Remarkably, we find that the magnetic ground state
structure changes from a G-type antiferromagnetic structure in Sr2Mn3As2O2 to
an A-type ferrimagnetic structure in Sr2Mn2CuAs2O2 in which the Mn ions in each
layer are ferromagnetically aligned, but are antiferromagnetically aligned
between layers.Comment: 18 pages, 16 figures, 6 tables; submitted to Phys. Rev.
Analysis and Observations from the First Amazon Picking Challenge
This paper presents a overview of the inaugural Amazon Picking Challenge
along with a summary of a survey conducted among the 26 participating teams.
The challenge goal was to design an autonomous robot to pick items from a
warehouse shelf. This task is currently performed by human workers, and there
is hope that robots can someday help increase efficiency and throughput while
lowering cost. We report on a 28-question survey posed to the teams to learn
about each team's background, mechanism design, perception apparatus, planning
and control approach. We identify trends in this data, correlate it with each
team's success in the competition, and discuss observations and lessons learned
based on survey results and the authors' personal experiences during the
challenge
X-ray scattering from surfaces: discrete and continuous components of roughness
Incoherent surface scattering yields a statistical description of the
surface, due to the ensemble averaging over many independently sampled volumes.
Depending on the state of the surface and direction of the scattering vector
relative to the surface normal, the height distribution is discrete,
continuous, or a combination of the two. We present a treatment for the
influence of multimodal surface height distributions on Crystal Truncation Rod
scattering. The effects of a multimodal height distribution are especially
evident during in situ monitoring of layer-by-layer thin-film growth via Pulsed
Laser Deposition. We model the total height distribution as a convolution of
discrete and continuous components, resulting in a broadly applicable
parameterization of surface roughness which can be applied to other scattering
probes, such as electrons and neutrons. Convolution of such distributions could
potentially be applied to interface or chemical scattering. Here we find that
this analysis describes accurately our experimental studies of SrTiO3
annealing and homoepitaxial growth.Comment: 15 pages, 7 figure
Homotransplantation of multiple visceral organs
It was technically possible to perform simultaneous homotransplantation of multiple visceral organs including the liver, spleen, pancreas, omentum and the entire gastrointestinal tract. Arterialization of the cooled graft was accomplished through the donor aorta which was removed with the graft and attached to that of the recipient dog. Gastrointestinal hemorrhage after surgery accounted for a high operative mortality and was thought to be due to denervation of the graft. The five dogs which survived the immediate trauma of surgery lived for five and a half to nine days. After the second day, these animals were physically active and able to resume oral alimentation. In three dogs, there was metabolic evidence of rejection of the liver. In two others, jaundice did not develop. These observations were compared with chemical, hematologic and pathologic data obtained in previous experiments involving homotransplantation of the liver alone. In some cases, there was less evidence of host versus graft rejection after the multiple organ transplants. Other data in the present study suggested the possibility that a significant graft versus host reaction may have been an important contributory cause of death. © 1962
Disturbances in the natural oxidation-reduction equilibrium of milk with special reference to the use of dehydrated milks in the manufacture of cottage cheese
Publication authorized June 29, 1934."The data presented in this bulletin were taken from a paper submitted by the junior author in partial fulfillment of the requirements for the degree of Master of Arts in the Graduate School of the University of Missouri, 1934"--P. [3].Includes bibliographical references (page 26)
Catastrophic Phase Transitions and Early Warnings in a Spatial Ecological Model
Gradual changes in exploitation, nutrient loading, etc. produce shifts
between alternative stable states (ASS) in ecosystems which, quite often, are
not smooth but abrupt or catastrophic. Early warnings of such catastrophic
regime shifts are fundamental for designing management protocols for
ecosystems. Here we study the spatial version of a popular ecological model,
involving a logistically growing single species subject to exploitation, which
is known to exhibit ASS. Spatial heterogeneity is introduced by a carrying
capacity parameter varying from cell to cell in a regular lattice. Transport of
biomass among cells is included in the form of diffusion. We investigate
whether different quantities from statistical mechanics -like the variance, the
two-point correlation function and the patchiness- may serve as early warnings
of catastrophic phase transitions between the ASS. In particular, we find that
the patch-size distribution follows a power law when the system is close to the
catastrophic transition. We also provide links between spatial and temporal
indicators and analyze how the interplay between diffusion and spatial
heterogeneity may affect the earliness of each of the observables. We find that
possible remedial procedures, which can be followed after these early signals,
are more effective as the diffusion becomes lower. Finally, we comment on
similarities and differences between these catastrophic shifts and paradigmatic
thermodynamic phase transitions like the liquid-vapour change of state for a
fluid like water
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