Quarkonium polarization in pp and p-nucleus collisions

The existing measurements of quarkonium polarization in proton-antiproton and proton-nucleus collisions are puzzling. We highlight issues which are often underestimated in the experimental analyses: the importance of the choice of the experimental acceptance on the comparison between experimental measurements and theoretical calculations. New measurements must provide more detailed information, such that physical conclusions can be derived without relying on model-dependent assumptions. We also describe a frame-invariant formalism which minimizes the dependence of the measurements on the experimental acceptance, facilitates the comparison with theoretical calculations, and probes systematic effects due to experimental biases.     

Correlation-induced spectral changes in tissues

We report experimental evidence of correlation-induced spectral changes in biological tissues. The overall spectral shift in our transmission measurements is to the red and the mean wavelength of the original spectrum is up 10% larger. These results indicate that the spectral changes due to elastic scattering are significant and likely to hinder all spectroscopic measurements based on the inelastic (i.e., emission and absorption) interaction between light and tissues. Thus, simultaneous morphology and spectral measurements are required for accurate measurements spectroscopic information.     

核磁共振扩散测量和q-空间成像进展(英文)

在过去的近半个世纪, NMR扩散测量在理论和实践方面都不断取得进展,使得测量更加可靠和准确,并能获取越来越多的信息.随着扩散测量技术的发展,其科学应用范围也不断增加,覆盖从物理化学到临床医学等各个领域. NMR扩散测量不仅能提供分子的平移运动动力学信息,而且也可以提供影响平移运动的局部几何结构的信息,后一种应用通常称为q-空间成像.该综述聚焦于过去10年中的NMR扩散研究方面一些重大的进展.     

Effect of track stiffness on vibration levels in railway tunnels

The paper discusses the difficulties in comparing and drawing conclusions from vibration measurements made in different railway tunnels. A number of new measurements are presented, which have been made and analyzed on a consistent basis. The track stiffness has been determined for each of the measurements. Graphs are presented which indicate the level of rail and tunnel floor vibration likely to occur for different track stiffnesses. The variance in the measurement results also indicates the potential error in using the data to predict vibration levels in new situations.     

Qualitative acoustic analysis in the study of motor speech disorders.

Traditional measurements performed on the acoustic signals of normal speech are frequently used to quantify the acoustic characteristics of disordered speech as well. This letter demonstrates how important aspects of speech production deficits in motor speech disorders may be overlooked if stringent quantification procedures are employed, especially in the stage of exploratory data analysis. It is suggested that qualitative procedures, wherein phenomena are inferred from visual examination of certain acoustic displays, are useful to supplement traditional measurements, and moreover, that they be used to point to the types of measurements that should be made in the finer-grained stages of quantitative analysis.     

The thermal contact problem in nano- and micro-scale photothermal measurements

Thermal contact resistance between two solids is discussed with regard to its influence on the measurements of temperature and thermo-physical parameters in micro- and nano-structures. Two important applications are considered: thin film coatings on substrates and local measurements with a nano-probe in scanning thermal microscopy. The mechanical contact of a copper layer on carbon is measured by adhesion strength experiments and correlated to the thermal transport across the interface deduced from infrared radiometric measurements. A novel quantity the thermal wave contrast is introduced which takes into account the interface resistance and modifications of the coating and substrates at the interface. With regard to scanning thermal microscopy the contact resistance problem is discussed for 3ω-measurements in the active mode and for temperature measurements in the passive mode. It is shown that the thermo-elastic response can offer a means to avoid the influence of the thermal contact resistance on local temperature measurements.     

Measurements of the low temperature heat capacity of niobium in the superconducting mixed state

Low temperature measurements of the heat capacity of niobium in the mixed state obtained at constant magnetic induction are presented, and are compared with the heat capacity expected form electronic excitations bound to the cores of individual flux lines. The formation of the intermediate mixed state is shown to have a pronounced influence on measurements at elevated temperatures and complicates comparison with theory at low temperatures. Our measurements are qualitatively consistent with the reduction in core size with decreasing temperature recently predicted by Kramer and Pesch.     

On-line measurement of temperature and water vapor in CH_4 /air premixed flame using near-infrared diode laser

We establish a single diode laser sensor system to obtain temperature and water concentration in CH4/air premixed flame.Line-of-sight properties are analyzed,but line-of-sight results are not path average values for temperature measurements.The measurements are performed on a flat burner based on scannedwavelength direct absorption spectroscopy using two adjacent water lines at 7153.75 and 7154.35 cm 1.Real-time results are acquired using a data acquisition card with a Labview data processing program.The standard uncertainties of the temperature and water concentration measurements are 2.3% and 5.1%,respectively.     

Development of methods of precise ultrasonic measurements in small volumes of liquids

The application of ultrasonic methods to investigation of problems of molecular physics and molecular biology is greatly limited by the necessity of precise measurements of ultrasound velocity and absorption in small volumes of liquids. Fixed path interferometric methods are the most adequate for such measurements in the low MHz region.In this paper disadvantages of the present interferometric methods of ultrasonic measurements are considered and new resonator cells and a simple device for such measurements are described. Accuracies of 10^?4% for the velocity change and to better than 1% for the attenuation change, at frequencies of about 7 MHz, are obtained by the device described. The volumes of the resonator cells vary within 0.1 to 0.8 ml depending on the purpose of investigation.     

New traceability chains in the photometric and radiometric measurements at the National Metrology Institute of Turkey

Optical Standards Laboratory of the National Metrology Institute of Turkey (UME) performs photometric, radiometric and fiber optics measurements related to SI-based units. The new traceability chains in the photometric and radiometric measurements are established in 2004, where top of the chains is based on primary-level optical power measurements with a cryogenic radiometer facility.     

Spectroscopic,calibration and RET issues for linear laser-induced fluorescence measurements of nitric oxide in high-pressure diffusion flames

Two different strategies are compared for linear laser-induced fluorescence (LIF) measurements of nitric oxide concentration ([NO]) in counter-flow diffusion flames at high pressures via the A-X(0,0) system. Excitation of NO via a rovibronic transition at 226.03 nm is found to be slightly better compared to a previously utilized excitation wavelength of 225.58 nm. An indirect approach based on the computed spectral overlap fraction is verified and applied to calibrate [NO] measurements in counter-flow diffusion flames at high pressures. A five-level model for NO molecular dynamics is presented and utilized to investigate the effects of rotational energy transfer (RET) on linear LIF measurements of [NO] at pressures up to 15 atm. The results indicate that rotational relaxation effects are essentially negligible under high-pressure conditions at low laser fluences, and thus they need not be accounted for when measuring [NO] using linear LIF. The calibration technique is validated by direct comparisons to [NO] measurements made at pressures up to 5 atm via another calibration method, based on doping NO in counter-flow premixed flames at the same pressure. Using this calibration technique, LIF measurements of [NO] are obtained in a series of counter-flow diffusion flames at pressures up to 15 atm. These measurements are found to be in excellent agreement with previously reported measurements of [NO] in similar flames. PACS 07.35.+k; 33.20.Sn; 42.62.Fi     

High Probe Intensity Photobleaching Measurement of Lateral Diffusion in Cell Membranes

Lateral diffusion measurements, most commonly accomplished through Fluorescence Photobleaching Recovery (FPR or FRAP), provide important information on cell membrane molecules' size, environment and participation in intermolecular interactions. However, serious difficulties arise when these techniques are applied to weakly expressed proteins of either of two types: fusions of membrane receptors with visible fluorescent proteins or membrane molecules on autofluorescent cells. To achieve adequate sensitivity in these cases, techniques such as interference fringe FPR are needed. However, in such measurements, cytoplasmic species contribute to the fluorescence recovery signal and thus yield diffusion parameters not properly representing the small number of surface molecules. A new method helps eliminate these difficulties. High Probe Intensity (HPI)-FPR measurements retain the intrinsic confocality of spot measurements to eliminate interference from fluorescent cytoplasmic species. However, HPI-FPR methods lift the previous requirement that FPR procedures be performed at probe beam intensities low enough to not induce bleaching in samples during measurements. The high probe intensities now employed provide much larger fluorescence signals and thus more information on molecular diffusion from each measurement. We report successful measurement of membrane dynamics by this technique.     

Measurement of wind noise levels in streamlined probes

This paper investigates the wind noise pressure spectra measured by aerodynamically designed devices in turbulent flow. Such measurement probes are often used in acoustic measurements in wind tunnels to reduce the pressure fluctuations generated by the interaction of the devices with the incident flow. When placed in an outdoor turbulent environment however, their performance declines noticeably. It is hypothesized that these devices are measuring the stagnation pressures generated by the cross flow components of the turbulence. Predictions for the cross flow contribution to the stagnation pressure spectra based on measured velocity spectra are developed, and are then compared to the measured pressure spectra in four different probe type devices in windy conditions outdoors. The predictions agree well with the measurements and show that the cross flow contamination coefficient is on the order of 0.5 in outdoor turbulent flows in contrast to the published value of 0.15 for measurements in a turbulent jet indoors.     

Effect of humidity in charge formation and transport in LDPE

Charge distribution and transport have been investigated in LDPE films with different humidity content under electric fields up to 130 MV/m. Pulsed electroacoustic measurements showed that, as water content increases, positive charge packets formation in the anode is enhanced and they propagate toward the cathode with higher transit speeds. Fits of surface potential decay measurements showed that charges in dry samples are injected directly into the volume, but the presence of moisture generates new trap centers in the surface of the material. This new trap level causes a charge accumulation on the surface, that gradually passes into the bulk. The observed behavior in development and propagation of charge packets are explained according to these results. Thermally stimulated depolarization current measurements showed a non-distributed relaxation associated to the new trap levels on the surface of the wet samples.     

Transmission studies on three graded-index fibre cable links installed in operational ducts

This paper reports the transmission measurements made on 40 km of graded-index fibre which have been cabled and installed in operational ducts for use in 8 and 140 Mbits^–1 systems. Extensive loss and bandwidth measurements were made at all stages of the programme, both before and after cabling and also in the field using two mobile test vehicles. The problems of obtaining meaningful and reproducible measurements are discussed and the stability of the measurements between the various cabling and installation stages is assessed. The results have been analysed in conjunction with additional laboratory measurements and a number of important propagation effects have been brought to light.Partial reports of this work have been given at the Colloquium on Optical Fibre Cable, IEE, London, May 1977 and at the Third European Conference on Optical Communications in Munich, September 1977.     

Correction of imaging errors in spatially resolved laser scattering experiments in flames

Imaging errors in spatially resolved measurements using laser scattering techniques in flames are discussed. An experimental method based on Fourier deconvolution to correct the measurements for the imaging errors is presented. The method is especially important when large gradients are recorded with lowf-number lenses in order to obtain a sufficient signal-to-noise ratio. The technique is demonstrated experimentally on OH profiles measured by laser-induced fluorescence in an atmospheric acetylen-oxygen flame.     

Driftgeschwindigkeit von Elektronen in Argon

Drift velocities of electrons in pure argon are derived from measurements of transit times in a homogeneous electric field. The electron avalanches are initiated by the light pulse of a spark, and the current of electrons is observed. The influence of the diffusion on the drift velocity measurements is taken into account.     

Dynamics of quantum zeno and anti-zeno efects in an open system

We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects in an open quantum system under repeated non-demolition measurements.In our approach the repeated measurements are described by a general dynamical model without the wave function collapse postulation.Based on that model,we further study both the short-time and long-time evolutions of the open quantum system under repeated non-demolition measurements,and derive the measurement-modified decay rates of the excited state.In the cases with frequent ideal measurements at zero-temperature,we re-obtain the same decay rate as that from the wave function collapse postulation(Nature,2000,405:546).The correction to the ideal decay rate is also obtained under the non-ideal measurements.Especially,we find that the quantum Zeno and anti-Zeno efects are possibly enhanced by the non-ideal natures of measurements.For the open system under measurements with arbitrary period,we generally derive the rate equation for the long-time evolution for the cases with arbitrary temperature and noise spectrum,and show that in the long-time evolution the noise spectrum is efectively tuned by the repeated measurements.Our approach is also able to describe the quantum Zeno and anti-Zeno efects given by the phase modulation pulses,as well as the relevant quantum control schemes.     

Dynamics of quantum zeno and anti-zeno effects in an open system

We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects in an open quantum system under repeated non-demolition measurements.In our approach the repeated measurements are described by a general dynamical model without the wave function collapse postulation.Based on that model,we further study both the short-time and long-time evolutions of the open quantum system under repeated non-demolition measurements,and derive the measurement-modified decay rates of the excited state.In the cases with frequent ideal measurements at zero-temperature,we re-obtain the same decay rate as that from the wave function collapse postulation(Nature,2000,405:546).The correction to the ideal decay rate is also obtained under the non-ideal measurements.Especially,we find that the quantum Zeno and anti-Zeno efects are possibly enhanced by the non-ideal natures of measurements.For the open system under measurements with arbitrary period,we generally derive the rate equation for the long-time evolution for the cases with arbitrary temperature and noise spectrum,and show that in the long-time evolution the noise spectrum is efectively tuned by the repeated measurements.Our approach is also able to describe the quantum Zeno and anti-Zeno efects given by the phase modulation pulses,as well as the relevant quantum control schemes.