Search

Individuals with Down syndrome (DS) appear to perform at a level that is commensurate with developmental expectations on simple tasks of selective attention. In this study, we examine how their selective attention is impacted by target changes that unfold over both time and space. This increased complexity reflects an attempt at greater ecological validity in an experimental task, as a steppingstone for better understanding attention among persons with DS in real-world environments.A modified flanker task was used to assess visual temporal and spatial filtering among persons with DS (n = 14) and typically developing individuals (n = 14) matched on non-verbal mental age (mental age = 8.5 years). Experimental conditions included varying the stimulus onset asynchronies between the onset of the target and flankers, the distances between the target and flankers, and the similarity of the target and flankers.Both the participants with DS and the typically developing participants showed slower reaction times and lower accuracy rates when the flankers appeared closer in time and/or space to the target.No group differences were found on a broad level, but the findings suggest that dynamic stimuli may be processed differently by those with DS. Implications of the findings are discussed in relation to the developmental approach to intellectual disability originally articulated by Ed Zigler.

Single dopant atoms or dopant-related defect centers in a solid state matrix provide an attractive platform for quantum simulation of topological states, for quantum computing and communication, due to their potential to realize a scalable architecture compatible with electronic and photonic integrated circuits. The production of such quantum devices calls for deterministic single atom doping techniques because conventional stochastic doping techniques are cannot deliver appropriate architectures. Here, we present the fabrication of arrays of praseodymium color centers in YAG substrates, using a deterministic source of single laser-cooled Pr$^+$ ions. The beam of single Pr$^+$ ions is extracted from a Paul trap and focused down to 30(9) nm. Using a confocal microscope we determine a conversion yield into active color centers up to 50% and realizing a placement accuracy of better than 50 nm., Comment: 9 pages, 7 figures

Trapped ions in linear Paul traps have been established as a powerful platform for performing experiments in quantum optics, quantum computing, quantum simulation, quantum control, and more recently in quantum thermodynamics. For the latter, modification of the trap geometry can facilitate the study of thermodynamic effects in the motional degrees of freedom. For instance, tapering the radial confinement of a trapped ion gives rise to temperature-dependent forces, where the definition of temperature is based on the concept of thermal states defined as an average in the time domain. It has recently been shown that such tapered traps can be used to realise single atom heat engines, where classical notions such as thermal reservoirs, heat transfer, work, internal energy, power and efficiency can be studied at quantum length scales. In this chapter, we introduce the tapered trap platform and present a basic description of it in the quantum regime.

The melting point (TM) of fat is relevant to health, but available methods of determining TM are cumbersome. One of the standard methods of measuring TM for animal and vegetable fats is the slip point, also known as the open capillary method. This method is imprecise and not amenable to automation or mass testing. We have developed a technique for measuring TM of animal fat using the Rotor-Gene Q (Qiagen, Hilden, Germany). The assay has an intra-assay SD of 0.08°C. A single operator can extract and assay up to 250 samples of animal fat in 24 h, including the time to extract the fat from the adipose tissue. This technique will improve the quality of research into genetic and environmental contributions to fat composition of meat.

The aim of this study was to investigate aerobic exercise training as a means to prevent erectile dysfunction (ED) and coronary artery disease (CAD) development associated with inactivity and diet-induced obesity. Male Sprague-Dawley rats were fed a Western diet (WD) or a control diet (CD) for 12 wk. Subgroups within each diet remained sedentary (Sed) or participated in aerobic interval treadmill running throughout the dietary intervention. Erectile function was evaluated under anesthesia by measuring the mean arterial pressure and intracavernosal pressure in response to electrical field stimulation of the cavernosal nerve, in the absence or presence of either apocynin, an NADPH oxidase inhibitor, or sepiapterin, a tetrahydrobiopterin precursor. Coronary artery endothelial function (CAEF) was evaluated ex vivo with cumulative doses of ACh applied to preconstricted segments of the left anterior descending coronary artery. CAEF was assessed in the absence or presence of apocynin or sepiapterin. Erectile function ( P < 0.0001) and CAEF ( P < 0.001) were attenuated in WD-Sed. Exercise preserved erectile function ( P < 0.0001) and CAEF ( P < 0.05) within the WD. Erectile function ( P < 0.01) and CAEF ( P < 0.05) were augmented by apocynin only in WD-Sed, while sepiapterin ( P < 0.05) only augmented erectile function in WD-Sed. These data demonstrate that a chronic WD induces impairment in erectile function and CAEF that are commonly partially reversible by apocynin, whereas sepiapterin treatment exerted differential functional effects between the two vascular beds. Furthermore, exercise training may be a practical means of preventing diet-induced ED and CAD development.

We demonstrate optical transport of cold cesium atoms over millimeter-scale distances along an optical nanofiber. The atoms are trapped in a one-dimensional optical lattice formed by a two-color evanescent field surrounding the nanofiber, far red- and blue-detuned with respect to the atomic transition. The blue-detuned field is a propagating nanofiber-guided mode while the red-detuned field is a standing-wave mode which leads to the periodic axial confinement of the atoms. Here, this standing wave is used for transporting the atoms along the nanofiber by mutually detuning the two counter-propagating fields which form the standing wave. The performance and limitations of the nanofiber-based transport are evaluated and possible applications are discussed.

Making a teeny tiny engine Steam locomotives, cars, and the drinking bird toy all convert heat into useful work as it cycles between two reservoirs at different temperatures. Usually, the working substance where the heat-work conversion occurs is a liquid or a gas, consisting of many molecules. Roβnagel et al. have made a working substance of a single calcium ion in a tapered ion trap. A laser-cooling beam plays the part of a cold reservoir for the calcium ion, and in turn, electric field noise acts as a hot reservoir. Science , this issue p. 325

We realize a single particle microscope by using deterministically extracted laser-cooled ^{40}Ca^{+} ions from a Paul trap as probe particles for transmission imaging. We demonstrate focusing of the ions to a spot size of 5.8±1.0 nm and a minimum two-sample deviation of the beam position of 1.5 nm in the focal plane. The deterministic source, even when used in combination with an imperfect detector, gives rise to a fivefold increase in the signal-to-noise ratio as compared with conventional Poissonian sources. Gating of the detector signal by the extraction event suppresses dark counts by 6 orders of magnitude. We implement a Bayes experimental design approach to microscopy in order to maximize the gain in spatial information. We demonstrate this method by determining the position of a 1 μm circular hole structure to a precision of 2.7 nm using only 579 probe particles.

We have developed an ultra-stable source in the deep ultraviolet, suitable to fulfill the interrogation requirements of a future fully-operational lattice clock based on neutral mercury. At the core of the system is a Fabry-P\'erot cavity which is highly impervious to temperature and vibrational perturbations. The mirror substrate is made of fused silica in order to exploit the comparatively low thermal noise limits associated with this material. By stabilizing the frequency of a 1062.6 nm Yb-doped fiber laser to the cavity, and including an additional link to LNE-SYRTE's fountain primary frequency standards via an optical frequency comb, we produce a signal which is both stable at the 1E-15 level in fractional terms and referenced to primary frequency standards. The signal is subsequently amplified and frequency-doubled twice to produce several milliwatts of interrogation signal at 265.6 nm in the deep ultraviolet., Comment: 7 pages, 6 figures

Soil applied granular nematicide efficacy may be compromised by the use of new soil tillage techniques which are potentially unsuitable for incorporating granular nematicides. A technique was developed to aid the selection of potato ( Solanum tuberosum L.) seed-bed preparation machinery suitable for incorporating granular nematicides. The technique uses photography to record the distribution of fluorescent tracer granules in excavated soil profiles. Experimentation at Harper Adams University College, Newport, UK with different photographic techniques has resulted in a method which will reliably record granule distributions in the field using inexpensive apparatus. Tracer distributions achieved by key granular nematicide incorporation methods indicated that the stone separator (with granule application towards the front of the machine) or a spiked rotavator incorporated nematicide granules to a depth of 15–20 cm. Incorporating granules initially by bed tilling and then by stone separation produced a deep incorporation to a depth of 35 cm. However, the stone separator alone with granule application half-way up the main separation web produced a shallow incorporation 5 cm deep. It is suggested that the techniques which caused a deep granule incorporation to 35 cm and a shallow granule incorporation to 5 cm are unsuitable for incorporating granular nematicides.

The Chebyshev?tau spectral method for approximating eigenvalues of boundary value problems may produce spurious eigenvalues with large positive real parts, even when all true eigenvalues of the problem are known to have negative real parts. We explain the origin and nature of the “spurious eigenvalues” in an example problem. The explanation will demonstrate that the large positive eigenvalues are an approximation of infinite eigenvalues in a nearby generalized eigenvalue problem.

The purpose of this study was to investigate NADPH oxidase as a common mechanism underlying both erectile dysfunction (ED) and coronary artery disease (CAD) in inactivity and diet-induced obesity. ...

Traversal of a symmetry-breaking phase transition at finite rates can lead to causally separated regions with incompatible symmetries and the formation of defects at their boundaries, which has a crucial role in quantum and statistical mechanics, cosmology and condensed matter physics. This mechanism is conjectured to follow universal scaling laws prescribed by the Kibble-Zurek mechanism. Here we determine the scaling law for defect formation in a crystal of 16 laser-cooled trapped ions, which are conducive to the precise control of structural phases and the detection of defects. The experiment reveals an exponential scaling of defect formation γ(β), where γ is the rate of traversal of the critical point and β=2.68±0.06. This supports the prediction of β=8/3≈2.67 for finite inhomogeneous systems. Our result demonstrates that the scaling laws also apply in the mesoscopic regime and emphasizes the potential for further tests of non-equilibrium thermodynamics with ion crystals.

We realize fast transport of ions in a segmented micro-structured Paul trap. The ion is shuttled over a distance of more than 10^4 times its groundstate wavefunction size during only 5 motional cycles of the trap (280 micro meter in 3.6 micro seconds). Starting from a ground-state-cooled ion, we find an optimized transport such that the energy increase is as low as 0.10 $\pm$ 0.01 motional quanta. In addition, we demonstrate that quantum information stored in a spin-motion entangled state is preserved throughout the transport. Shuttling operations are concatenated, as a proof-of-principle for the shuttling-based architecture to scalable ion trap quantum computing., Comment: 5 pages, 4 figures

We present experimental techniques and results related to the optimization and characterization of our nanofiber-based atom trap [Vetsch et al., Phys. Rev. Lett. 104, 203603 (2010)]. The atoms are confined in an optical lattice which is created using a two-color evanescent field surrounding the optical nanofiber. For this purpose, the polarization state of the trapping light fields has to be properly adjusted. We demonstrate that this can be accomplished by analyzing the light scattered by the nanofiber. Furthermore, we show that loading the nanofiber trap from a magneto-optical trap leads to sub-Doppler temperatures of the trapped atomic ensemble and yields a sub-Poissonian distribution of the number of trapped atoms per trapping site.

We dispersively interface an ensemble of one thousand atoms trapped in the evanescent field surrounding a tapered optical nanofiber. This method relies on the azimuthally-asymmetric coupling of the ensemble with the evanescent field of an off-resonant probe beam, transmitted through the nanofiber. The resulting birefringence and dispersion are significant; we observe a phase shift per atom of $\sim$\,1\,mrad at a detuning of six times the natural linewidth, corresponding to an effective resonant optical density per atom of 0.027. Moreover, we utilize this strong dispersion to non-destructively determine the number of atoms., 4 pages, 4 figures

Pulling a standard optical fiber to a diameter of less than the wavelength of the guided light causes the light field to project slightly over the fiber boundaries in form of an evanescent wave. The latter can be used for light-matter-interactions in the vicinity of the surface of the fiber and therefore allows to perform quantum optic experiments.

Studies in two dimensions have been made of the evolution of an initially linear interface between two liquid areas by both continuum hydrodynamics and molecular dynamics. It was found that at both levels the interface evolves into a fractal curve. While the limiting fractal dimensionalities (D) of the continuum and molecular interfaces differ, this difference is no greater than that that can be induced in the hydrodynamic results by marked changes in the initial conditions and/or fluid parameters. There is, however, a marked qualitative difference in the initial values of D. This is discussed and shown to be a natural consequence of the molecular discreteness of the real liquids.

Trapping and optically interfacing laser-cooled neutral atoms is an essential requirement for their use in advanced quantum technologies. Here we simultaneously realize both of these tasks with cesium atoms interacting with a multi-color evanescent field surrounding an optical nanofiber. The atoms are localized in a one-dimensional optical lattice about 200 nm above the nanofiber surface and can be efficiently interrogated with a resonant light field sent through the nanofiber. Our technique opens the route towards the direct integration of laser-cooled atomic ensembles within fiber networks, an important prerequisite for large scale quantum communication schemes. Moreover, it is ideally suited to the realization of hybrid quantum systems that combine atoms with, e.g., solid state quantum devices.

In this paper, we report on development on an optical lattice clock using neutral mercury. Laser spectroscopy of the clock transition in fermionic isotope has been performed, which is an important step in this project.

We report direct laser spectroscopy of the $^{1}S_{0}\mathrm{\text{\ensuremath{-}}}^{3}P_{0}$ transition at 265.6 nm in fermionic isotopes of neutral mercury in a magneto-optical trap. Measurements of the frequency against the LNE-SYRTE primary reference using an optical frequency comb yield $1\text{ }128\text{ }575\text{ }290\text{ }808.4\ifmmode\pm\else\textpm\fi{}5.6\text{ }\text{ }\mathrm{kHz}$ in $^{199}\mathrm{Hg}$ and $1\text{ }128\text{ }569\text{ }561\text{ }139.6\ifmmode\pm\else\textpm\fi{}5.3\text{ }\text{ }\mathrm{kHz}$ in $^{201}\mathrm{Hg}$. The uncertainty, allowed by the observation of the Doppler-free recoil doublet, is 4 orders of magnitude lower than previous indirect determinations. Mercury is a promising candidate for future optical lattice clocks due to its low sensitivity to blackbody radiation.

We report direct laser spectroscopy of the 1S0-3P0 transition at 265.6 nm in fermionic isotopes of neutral mercury in a magneto-optical trap. Measurements of the frequency against the LNE-SYRTE primary reference using an optical frequency comb yield 1 128 575 290 808.4+/-5.6 kHz in 199Hg and 1 128 569 561 139.6+/-5.3 kHz in 201Hg. The uncertainty, allowed by the observation of the Doppler-free recoil doublet, is 4 orders of magnitude lower than previous indirect determinations. Mercury is a promising candidate for future optical lattice clocks due to its low sensitivity to blackbody radiation.

We present the design of two different geometries of optical cavities (vertically and horizontally mounted). The Finite Element Modeling analysis is used to predict and decrease the influence of vibrations on the cavity stabilized lasers. Inspired by the results of simulation, two cavities have been constructed. Vibration sensitivity coefficients measured are equal or better than 1.4x10-11/(m.s-2) for all spatial directions. A preliminary measurement of the two independent cavity stabilized lasers shows a relative frequency stability of about 10-15 @ 1s.

We demonstrate a method of controlling the alignment of a laser beam to a Fabry-Perot resonator through synchronous detection of the misalignment arising from modulating the orientation of a single beam-steering mirror. The horizontal and vertical tilt of the mirror are modulated in quadrature to drive a circular motion of the beam orientation. A corresponding modulation of the intensity of the optical field circulating in the cavity is measured at either the reflected or transmitted port and demodulated synchronously to derive two error signals to indicate the vertical and horizontal misalignment. These signals are fed back to the beam-steering mirror to suppress fluctuations below 30 Hz. This method avoids the complexity of monitoring off-axis cavity modes and is particularly effective in the case where unwanted pointing fluctuations are introduced by one or two elements in the optical setup. We have applied the technique to two Fabry-Perot resonators in use as precision frequency references, delivering a result of 10 dB suppression of alignment fluctuations at 1 Hz and an improvement in frequency stability by up to a factor of 4.

Summary The nature of the neutralizing antibody response in respiratory secretions to influenza virus has been compared in two groups of human volunteers, one given live virus via the respiratory tract and the other given dead virus parenterally. The “live-virus group” showed an antibody response in sputum and nasal washing that was significantly greater in magnitude and longer in duration than it was in the “dead-virus group.” There was no difference in the antibody response in saliva. In volunteers who were inoculated with live virus but showed no serum antibody rise, there was, nevertheless, a rise in sputum or nasal washing antibody. These results indicate that local infection is superior to parenteral immunization in inducing antibody in respiratory secretions.

Summary To investigate the hypothesis that the isolated lactase deficiency seen in healthy adults may be an acquired enzyme deficiency resulting from nonspecific insults or diseases, jejunal disaccharidase activity was measured in 6 volunteers who were challenged with Salmonella typhosa . Three were studied before and after the onset of clinical illness. Of the 6 individuals, 3 developed positive blood cultures and sustained fevers of greater than 103F for at least 2 days. There were no changes in lactase or other disaccharidase levels, and all values were within normal limits. Thus lactase deficiency was not produced by prolonged temperature elevations.

Serial measurements of the serum concentrations (as maximum binding capacities) of thyroxine binding prealbumin (TBPA), thyroxine binding globulin (TBG), PBI, free T4 (FT4), and percent free T4 (% FT4) were made before, during and after experimental infections (typhoid fever, tularemia and malaria) in 15 human subjects. In addition, the rate of disappearance of 125I-T4 from the circulation was determined. TBPA decreased during illness, but large initial decreases were dissociated in time from changes of FT4 and % FT4. Occasional but significant changes of TBG and PBI were unrelated to changes of TBPA and % FT4. PBI often dropped after the onset of illness, followed by a rebound which exceeded control values. These alterations of PBI alone resulted in significant FT4 changes in six cases. In two cases (malaria and shigeliosis) % FT3 changes paralleled changes of % FT4. In five subjects (two with typhoid fever and three with tularemia) increases of FT4 were not associated with any change in the rat...

In the United States, epidemic shigellosis has been a particularly important problem in confined groups such as the military, institutions for the mentally retarded, and Indian reservations. It is in such confined populations that an effective Shigella vaccine would be most beneficial. Shigella flexneri 2a is an important cause of both sporadic and epidemic shigellosis in the United States. Between the years 1963 and 1966 this pathogen accounted for approximately one-fourth of all Shigella isolates reported to the National Communicable Disease Center [1]. In 1967 this center recorded 11,405 isolations of all Shigella [2]. In order to test the effectiveness of oral attenuated living S. flexneri 2a vaccines, an experimental model has been developed in man. The response of volunteers to oral challenge by virulent S. flexneri 2a was determined at doses of 104 -108 viable organisms.

An experimental model of Rocky Mountain spotted fever (RMSF) was developed in man for quantitation of protective immunity induced by inactivated and viable pathogenic Rickettsia rickettsii. Attack rates were increased, and the incubation period shortened, by increasing the infecting dose of virulent rickettsiae. Administration of inactivated vaccines made from infected tick tissue or embryonated hens' eggs led to a rise in humoral antibodies in a low percentage of men. When given three to six months before exposure to virulent rickettsiae, both vaccines altered the response in volunteers by prolonging the incubation period and decreasing the frequency of clinical relapse. Six men who were four to 17 months convalescent from induced RMSF failed to develop clinical illness after challenge with 1 ID94 (94% infectious dose) of virulent rickettsiae. These studies indicate that solid immunity is imparted by RMSF illness, while inactivated vaccines offer minimal protection.

TYPHOID fever is a disease unique to man. No other animal species acquires an illness simulating typhoid fever after oral ingestion of the organism. This lack of a suitable experimental animal has hindered the acquisition of knowledge on pathogenesis and control. This presentation will summarize the experience gained in the study of healthy volunteers infected with typhoid bacilli. The purpose of these ongoing investigations has been to develop better methods of prevention and control of disease. The primary objective has been the quantitative evaluation of experimental and conventional vaccines. Such studies have permitted a careful analysis of pathogenesis. Typhoid vaccine . . .

Contents: Report on Q Fever Vaccine Studies; Demonstration of Viruses in Leukocytes by the Fluorescent Antibody Technique; Recovery of Viral Particles from Serum for Electron Microscopy; Effects of Ionizing Irradiation on the Immune Response to Venezuelan Equine Encephalomyelitis; Studies on the Pathogenesis and Control of Typhoid Fever; Role of Endotoxin during Typhoid Fever and Tularemia; Possible Polymer Configurations of Anthrax Toxin Components; Adrenal Function during Infectious Illness; Thyroid Function during Generalized Infection; Influence of Viral Infection on Host Protein and Ribonucleic Acid Biosynthesis; Protein Synthesis by Liver Cell Components of Mice Infected with Diplococcus pneumoniae; Alterations in Tissue Alkaline Phosphatase Activity during Acute Infection; Detection of Pasteurella pseudotuberculosis Antibodies by Microhemagglutination; Review of Virology Division Program; Comparative Pathology of Cutaneous Anthrax in the Immunized and Unimmunized Guinea Pig.

Amantadine hydrochloride is a synthetic salt of a symmetrical primary amine, shown by Davies and others [1], to have antiviral activity especially against A2 influenza virus (Fig. 1). Studies by these workers, conducted in tissue cultures, mice and chick embryos demonstrated that amantadine blocked or slowed viral penetration into host cells. Mice exposed to influenza virus and treated with this drug had enhanced survival rates and less tissue damage than untreated animals. Additional confirmatory investigations plus lack of significant toxicity prompted the assessment of amantadine in man. Preliminary evaluations of its prophylactic effectiveness in volunteers against induced A2 influenza infection were inconclusive. Failure to employ individuals free of demonstrable neutralizing antibodies against the challenge strain was responsible. Morris and others [2], have emphasized the necessity of selecting volunteers with no homotypic antibodies in order to be able to regularly produce influenza disease. This required a virus not previously epidemic in the area from which volunteers were to be drawn. Screening potential challenge strains of influenza virus indicated that Rockville/1/65 strain of A2 influenza was best suited because about 10% of our volunteers lacked or had low levels of neutralizing antibodies against it.

STUDIES with human volunteers have shown that experimental infection with influenza virus is a better stimulus of antibody in respiratory secretions than is subcutaneous immunization with inactivated vaccine, although both procedures result in the production of similar concentrations of serum antibody1,2. The work reported here was undertaken to determine if administration of inactivated virus vaccine through the respiratory tract provokes a similar antibody response in respiratory secretions.