Multiplexed optical operation of distributed nanoelectromechanical systems arrays.

We report a versatile all optical technique to excite and read-out a distributed nanoelectromechanical systems (NEMS) array. The NEMS array is driven by a distributed, intensity modulated optical pump through the photothermal effect. The ensuing vibrational response of the array is multiplexed onto a single probe beam in the form of a high frequency phase modulation. The phase modulation is optically down converted to a low frequency intensity modulation using an adaptive full-field interferometer, and subsequently detected using a CCD array. Rapid and single step mechanical characterization of ∼44 nominally identical high-frequency resonators is demonstrated. The technique may enable sensitivity improvements over single NEMS resonators by averaging signals coming from a multitude of devices in the array. In addition, the diffraction limited spatial resolution may allow for position-dependent read-out of NEMS sensor chips for sensing multiple analytes or spatially inhomogeneous forces.

Adaptive optical array receivers for detection of surface acoustic waves.

Adaptive interferometric detection systems based on two-wave mixing in photorefractive crystals have been configured as distributed optical receivers. The spatial distribution of the detection laser power on the sample surface is controlled by use of phase gratings and amplitude masks. The responses of point, line, array, and chirped optical receivers to propagating surface acoustic waves (SAW's) are discussed theoretically and demonstrated experimentally. It is shown that by use of different object beam footprints it is possible to configure adaptive holographic SAW receivers that are either broadband or narrow band and that are preferentially sensitive to SAW's propagating in given directions. The receivers also allow for the distribution of laser power over the sample, eliminating the excessive heating or surface damage that can occur in some materials when high power, point-focused, detection lasers are used.

Irradiated donor leukocytes promote engraftment of allogeneic bone marrow in major histocompatibility complex mismatched recipients without causing graft-versus-host disease.

Graft rejection in allogeneic bone marrow transplantation (BMT) can occur when donor and recipient are mismatched at one or more major histocompatibility complex (MHC) loci. Donor T cells can prevent graft rejection, but may cause fatal graft-versus-host disease (GVHD). We tested whether irradiation of allogeneic donor lymphocytes would preserve their graft-facilitating activity while inhibiting their potential for GVHD. Infusions of irradiated allogeneic T cells did not cause GVHD in MHC-mismatched SJL --> (SJL x C57BL6) F1, C57BL6 --> B10.RIII, and C57BL6 --> B10.BR mouse donor --> recipient BMT pairs. The 60-day survival among MHC-mismatched transplant recipients increased from 2% (BM alone) to up to 75% among recipients of BM plus irradiated allogeneic splenocytes. Optimal results were obtained using 50 x 10(6) to 75 x 10(6) irradiated donor splenocytes administered in multiple injections from day -1 to day +1. Recipients of an equal number of nonirradiated MHC-mismatched donor splenocytes uniformly died of acute GVHD. The graft facilitating activity of the irradiated allogeneic splenocytes was mediated by donor T cells. Irradiation to 7.5 Gy increased nuclear NFkappaB in T cells and their allospecific cytotoxicity. Irradiated T cells survived up to 3 days in the BM of MHC-mismatched recipients without proliferation. Recipients of irradiated allogeneic splenocytes and allogeneic BM had stable donor-derived hematopoiesis without a significant representation of donor splenocytes in the T-cell compartment. Irradiated allogeneic T cells thus represent a form of cellular immunotherapy with time-limited biologic activity in vivo that can facilitate allogeneic BMT without causing GVHD.

The effect of fluid and carbohydrate feedings during intermittent cycling exercise.

The purpose of this study was to determine the effect of ingesting water or carbohydrates solutions on physiologic function and performance during 1.6 h of intermittent cycling exercise in the heat (dry bulb temperature = 33 degrees C). Thirteen male subjects (24 to 35 yr) completed four separate rides. Each ride consisted of intermittent steady-state cycling (at 55 and 65% VO2max) interspersed with five rest periods. A timed 480 revolution cycling task completed each experimental session. During each rest period, subjects consumed 2 ml.kg-1 body weight of water placebo or solutions of 5% glucose polymer, 6% sucrose/glucose, or 7% glucose polymer/fructose. Beverages were administered in double-blind, counter-balanced order. No differences were observed among subjects in response to beverage treatments for changes in plasma concentrations of total proteins, sodium, potassium, lactate, or in osmolality, percent change in plasma volume, heart rate, oxygen uptake, respiratory exchange ratio, rating of perceived exertion, sweat rate, rectal temperature, or mean skin temperature. Compared to water placebo, the carbohydrate treatments produced higher plasma glucose values following 1 h cycling (P less than 0.01). Mean (SD) times for the 480 revolution cycling task: water placebo = 432 (43) s; glucose polymer = 401 (52) s; *sucrose/glucose = 384 (39) s; and *glucose polymer/fructose = 375 (30) s, where = P less than 0.001 compared to water placebo. Physiologic function was similarly maintained during exercise by all beverage treatments, while ingestion of sucrose/glucose and glucose polymer/fructose resulted in improved end-exercise cycling performance.