Molecular Fountain

The resolution of any spectroscopic or interferometric experiment is ultimately limited by the total time a particle is interrogated. We here demonstrate the first molecular fountain, a development which permits hitherto unattainably long interrogation times with molecules. In our experiments, ammonia molecules are decelerated and cooled using electric fields, launched upwards with a velocity between 1.4 and 1.9\,m/s and observed as they fall back under gravity. A combination of quadrupole lenses and bunching elements is used to shape the beam such that it has a large position spread and a small velocity spread (corresponding to a transverse temperature of $<$10\,$\mu$K and a longitudinal temperature of $<$1\,$\mu$K) when the molecules are in free fall, while being strongly focused at the detection region. The molecules are in free fall for up to 266\,milliseconds, making it possible to perform sub-Hz measurements in molecular systems and paving the way for stringent tests of fundamental physics theories

Thermal Diffusion and Specular Reflection, Monte Carlo-based Study on Human Skin via Pulsed Fiber Laser Energy

The aim of traditional Chinese medicine (TCM) in acupuncture is sometimes to restore and regulate energy balance by stimulating specific points along the specific meridians traced on the human body via different techniques such as mechanical pressure, moxibustion and others. Hence, physicians have struggled to improve treatment for common diseases such as migraine and headaches. Heat stimulation and some pharmacological effects from moxa have been attributed to the therapeutic efficacy of such techniques. As heat can diffuse through the tissue, skins temperature will rise in the surrounding tissue. In this work, heat diffusion on a simple, 5-layer model of human skin is presented. Based on this, and by using Monte Carlo techniques, a photon or a photon package is launched into the tissue for mimicking the propagation of such photons at two different wavelengths through the tissue. The method generally describes the scholastic nature of radiation interactions. Most of the laser energy is deposited within a volume which cross-sectional area is the size of the beam itself. As could be seen, in the epidermis layer of the model, the heat does not go deep and nearly all the heat diffusion occurs on the edges of the beam, causing losses. Heat dissipation occurs faster and goes down to 2°C in the adipose tissue since there is low water content in this region. On the contrary, there is a fast heat increase in the muscle layer, up to 6°C at the most superficial layer. Since melanin is the most important epidermal chromophore, it can be noted that light shows strong absorption via melanin, at 690nm laser wavelength. In the papillary dermis the heat decreases and spreads out to the surrounding tissue. Once it reaches the adipose tissue, the heat is not absorbed enough; therefore, it is transmitted into the muscle, where the temperature rise is higher and reaches nearly 40 °C. Finally, photodynamics in a simple 5-layer skin model were explored at two laser wavelengths: 690nm and 1069nm, where no thermal damage would be expected, given the energy level of the employed pulses. Such pulsed laser energy levels remain to be tested in living tissue

Intranuclear Inclusions of Expanded Polyglutamine Protein in Spinocerebellar Ataxia Type 3

AbstractThe mechanism of neurodegeneration in CAG/polyglutamine repeat expansion diseases is unknown but is thought to occur at the protein level. Here, in studies of spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/MJD), we show that the disease protein ataxin-3 accumulates in ubiquitinated intranuclear inclusions selectively in neurons of affected brain regions. We further provide evidence in vitro for a model of disease in which an expanded polyglutamine-containing fragment recruits full-length protein into insoluble aggregates. Together with recent findings from transgenic models, our results suggest that intranuclear aggregation of the expanded protein is a unifying feature of CAG/polyglutamine diseases and may be initiated or catalyzed by a glutamine-containing fragment of the disease protein

Interruption of the Arterial Inferior Alveolar Flow and its Effects on Mandibular Collateral Circulation and Dental Tissues

The interruption of circulation through the inferior alveolar artery was followed by the establishment of a fast retrograde blood flow through the vessel. The mental artery and the mandibular branch of the sublingual artery were the main vessels to contribute to that flow. No histopathologic changes were found in the experimental hemimandibles; however, temporary regressive changes were found in the dental pulps of molars.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67920/2/10.1177_00220345750540040301.pd

Power-law behaviour evaluation from foreign exchange market data using a wavelet transform method

Numerous studies in the literature have shown that the dynamics of many time series including observations in foreign exchange markets exhibit scaling behaviours. A simple new statistical approach, derived from the concept of the continuous wavelet transform correlation function (WTCF), is proposed for the evaluation of power-law properties from observed data. The new method reveals that foreign exchange rates obey power-laws and thus belong to the class of self-similarity processes. (C) 2009 Elsevier B.V. All rights reserved

Solitons in nonlocal nonlinear media: exact results

We investigate the propagation of one-dimensional bright and dark spatial solitons in a nonlocal Kerr-like media, in which the nonlocality is of general form. We find an exact analytical solution to the nonlinear propagation equation in the case of weak nonlocality. We study the properties of these solitons and show their stability.Comment: 9 figures, submitted to Phys. Rev.

Modulational instability in nonlocal nonlinear Kerr media

We study modulational instability (MI) of plane waves in nonlocal nonlinear Kerr media. For a focusing nonlinearity we show that, although the nonlocality tends to suppress MI, it can never remove it completely, irrespectively of the particular profile of the nonlocal response function. For a defocusing nonlinearity the stability properties depend sensitively on the response function profile: for a smooth profile (e.g., a Gaussian) plane waves are always stable, but MI may occur for a rectangular response. We also find that the reduced model for a weak nonlocality predicts MI in defocusing media for arbitrary response profiles, as long as the intensity exceeds a certain critical value. However, it appears that this regime of MI is beyond the validity of the reduced model, if it is to represent the weakly nonlocal limit of a general nonlocal nonlinearity, as in optics and the theory of Bose-Einstein condensates.Comment: 8 pages, submitted to Phys. Rev.

Phenomenology of Randall-Sundrum Black Holes

We explore the phenomenology of microscopic black holes in the $S^1/Z_2$ Randall-Sundrum (RS) model. We consider the canonical framework in which both gauge and matter fields are confined to the brane and only gravity spills into the extra dimension. The model is characterized by two parameters, the mass of the first massive graviton $(m_1)$, and the curvature $1/\ell$ of the RS anti-de Sitter space. We compute the sensitivity of present and future cosmic ray experiments to various regions of $\ell$ and $m_1,$ and compare with that of Runs I and II at the Tevatron. As part of our phenomenological analysis, we examine constraints placed on $\ell$ by AdS/CFT considerations.Comment: Version to appear in Physical Review D; contains additional analysis on sensitivity of OW

On the origin of M81 group extended dust emission

Galactic cirrus emission at far-infrared wavelengths affects many extragalactic observations. Separating this emission from that associated with extragalactic objects is both important and difficult. In this paper we discuss a particular case, the M81 group, and the identification of diffuse structures prominent in the infrared, but also detected at optical wavelengths. The origin of these structures has previously been controversial, ranging from them being the result of a past interaction between M81 and M82 or due to more local Galactic emission. We show that over an order of a few arcmin scales, the far-infrared (Herschel 250 mu m) emission correlates spatially very well with a particular narrow-velocity (2-3 km s(-1)) component of the Galactic HI. We find no evidence that any of the far-infrared emission associated with these features actually originates in the M81 group. Thus we infer that the associated diffuse optical emission must be due to galactic light-back scattered off dust in our galaxy. Ultraviolet observations pick out young stellar associations around M81, but no detectable far-infrared emission. We consider in detail one of the Galactic cirrus features, finding that the far-infrared HI relation breaks down below arcmin scales and that at smaller scales there can be quite large dust-temperature variation

Broken-Symmetry States in Quantum Hall Superlattices

We argue that broken-symmetry states with either spatially diagonal or spatially off-diagonal order are likely in the quantum Hall regime, for clean multiple quantum well (MQW) systems with small layer separations. We find that for MQW systems, unlike bilayers, charge order tends to be favored over spontaneous interlayer coherence. We estimate the size of the interlayer tunneling amplitude needed to stabilize superlattice Bloch minibands by comparing the variational energies of interlayer-coherent superlattice miniband states with those of states with charge order and states with no broken symmetries. We predict that when coherent miniband ground states are stable, strong interlayer electronic correlations will strongly enhance the growth-direction tunneling conductance and promote the possibility of Bloch oscillations.Comment: 9 pages LaTeX, 4 figures EPS, to be published in PR