Laser cooling and trapping of Yb from a thermal source

We have successfully loaded a magneto-optic trap for Yb atoms from a thermal source without the use of a Zeeman slower. The source is placed close to the trapping region so that it provides a large flux of atoms that can be cooled and captured. The atoms are cooled on the ${^1S_0} \leftrightarrow {^1P_1}$ transition at 398.8 nm. We have loaded all seven stable isotopes of Yb into the trap. For the most abundant isotope ($^{174}$Yb), we load more than $10^7$ atoms into the trap within 1 s. For the rarest isotope ($^{168}$Yb) with a natural abundance of only 0.13%, we still load about $4 \times 10^5$ atoms into the trap. We find that the trap population is maximized near a detuning of $-1.5\Gamma$ and field gradient of 75 G/cm.Comment: 4 figures, 6 page

High-accuracy wavemeter based on a stabilized diode laser

We have built a high-accuracy wavelength meter for tunable lasers using a scanning Michelson interferometer and a reference laser of known wavelength. The reference laser is a frequency stabilized diode laser locked to an atomic transition in Rb. The wavemeter has a statistical error per measurement of 5 parts in $10^7$ which can be reduced considerably by averaging. Using a second stabilized diode laser, we have verified that systematic errors are below 4 parts in $10^8$.Comment: 3 pages, 2 figure

Sub-natural linewidth in room-temperature Rb vapor using a control laser

We demonstrate two ways of obtaining sub-natural linewidth for probe absorption through room-temperature Rb vapor. Both techniques use a control laser that drives the transition from a different ground state. The coherent drive splits the excited state into two dressed states (Autler-Townes doublet), which have asymmetric linewidths when the control laser is detuned from resonance. In the first technique, the laser has a large detuning of 1.18 GHz to reduce the linewidth to 5.1 MHz from the Doppler width of 560 MHz. In the second technique, we use a counter-propagating pump beam to eliminate the first-order Doppler effect. The unperturbed probe linewidth is about 13 MHz, which is reduced below 3 MHz (0.5 \Gamma) at a detuning of 11.5 MHz.Comment: 4 pages, 7 figure

The Catechol-O-Methyltransferase (COMT) val158met Polymorphism Affects Brain Responses to Repeated Painful Stimuli

Despite the explosion of interest in the genetic underpinnings of individual differences in pain sensitivity, conflicting findings have emerged for most of the identified "pain genes". Perhaps the prime example of this inconsistency is represented by catechol-O-methyltransferase (COMT), as its substantial association to pain sensitivity has been reported in various studies, but rejected in several others. In line with findings from behavioral studies, we hypothesized that the effect of COMT on pain processing would become apparent only when the pain system was adequately challenged (i.e., after repeated pain stimulation). In the present study, we used functional Magnetic Resonance Imaging (fMRI) to investigate the brain response to heat pain stimuli in 54 subjects genotyped for the common COMT val158met polymorphism (val/val = n 22, val/met = n 20, met/met = n 12). Met/met subjects exhibited stronger pain-related fMRI signals than val/val in several brain structures, including the periaqueductal gray matter, lingual gyrus, cerebellum, hippocampal formation and precuneus. These effects were observed only for high intensity pain stimuli after repeated administration. In spite of our relatively small sample size, our results suggest that COMT appears to affect pain processing. Our data demonstrate that the effect of COMT on pain processing can be detected in presence of 1) a sufficiently robust challenge to the pain system to detect a genotype effect, and/or 2) the recruitment of pain-dampening compensatory mechanisms by the putatively more pain sensitive met homozygotes. These findings may help explain the inconsistencies in reported findings of the impact of COMT in pain regulation.United States. National Institutes of Health (R01AT005280)United States. National Institutes of Health (R21AT00949)United States. National Institutes of Health (KO1AT003883)United States. National Institutes of Health (R21AT004497)National Center for Complementary and Alternative Medicine (U.S.) (PO1-AT002048)United States. National Institutes of Health (M01-RR-01066)United States. National Institutes of Health (UL1 RR025758-01)United States. National Institutes of Health (P41RR14075)United States. National Institutes of Health (DE-FG03-99ER62764)Swedish Society for Medical Researc

Loading of a Rb magneto-optic trap from a getter source

We study the properties of a Rb magneto-optic trap loaded from a commercial getter source which provides a large flux of atoms for the trap along with the capability of rapid turn-off necessary for obtaining long trap lifetimes. We have studied the trap loading at two different values of background pressure to determine the cross-section for Rb--N$_2$ collisions to be 3.5(4)x10^{-14} cm^2 and that for Rb--Rb collisions to be of order 3x10^{-13} cm^2. At a background pressure of 1.3x10^{-9} torr, we load more than 10^8 atoms into the trap with a time constant of 3.3 s. The 1/e lifetime of trapped atoms is 13 s limited only by background collisions.Comment: 5 pages, 5 figure

Enhanced reactivity to pain in patients with rheumatoid arthritis

Introduction: Maladaptive physiological responses to stress appear to play a role in chronic inflammatory diseases such as rheumatoid arthritis (RA). However, relatively little stress research in RA patients has involved the study of pain, the most commonly reported and most impairing stressor in RA. In the present study, we compared psychophysical and physiological responses to standardized noxious stimulation in 19 RA patients and 21 healthy controls. Methods: Participants underwent a single psychophysical testing session in which responses to a variety of painful stimuli were recorded, and blood samples were taken at multiple time points to evaluate the reactivity of cortisol, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) to the experience of acute pain. Results: The findings suggest that RA patients display a fairly general hyperalgesia to mechanical and thermal stimuli across several body sites. In addition, while serum cortisol levels did not differ at baseline or following pain testing in patients relative to controls, the RA patients tended to show elevations in serum IL-6 and demonstrated enhanced pain-reactivity of serum levels of TNF-α compared with the healthy controls (P < 0.05). Conclusions: These findings highlight the importance of pain as a stressor in RA patients and add to a small body of literature documenting amplified responses to pain in RA. Future studies of the pathophysiology of RA would benefit from the consideration of acute pain levels when comparing RA patients with other groups, and future trials of analgesic interventions in RA patients may benefit from evaluating the effects of such interventions on inflammatory activity

A Longitudinal Study of the Reliability of Acupuncture Deqi Sensations in Knee Osteoarthritis

Deqi is one of the core concepts in acupuncture theory and encompasses a range of sensations. In this study, we used the MGH Acupuncture Sensation Scale (MASS) to measure and assess the reliability of the sensations evoked by acupuncture needle stimulation in a longitudinal clinical trial on knee osteoarthritis (OA) patients. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used as the clinical outcome. Thirty OA patients were randomized into one of three groups (high dose, low dose, and sham acupuncture) for 4 weeks. We found that, compared with sham acupuncture, real acupuncture (combining high and low doses) produced significant improvement in knee pain (P = .025) and function in sport (P = .049). Intraclass correlation analysis showed that patients reliably rated 11 of the 12 acupuncture sensations listed on the MASS and that heaviness was rated most consistently. Overall perceived sensation (MASS Index) (P = .014), ratings of soreness (P = .002), and aching (P = .002) differed significantly across acupuncture groups. Compared to sham acupuncture, real acupuncture reliably evoked stronger deqi sensations and led to better clinical outcomes when measured in a chronic pain population. Our findings highlight the MASS as a useful tool for measuring deqi in acupuncture research

The Somatosensory Link in Fibromyalgia: Functional Connectivity of the Primary Somatosensory Cortex Is Altered by Sustained Pain and Is Associated With Clinical/Autonomic Dysfunction

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111091/1/art39043.pd

Neural Correlates of Chronic Low Back Pain Measured by Arterial Spin Labeling

Background The varying nature of chronic pain (CP) is difficult to correlate to neural activity using typical functional magnetic resonance imaging methods. Arterial spin labeling is a perfusion-based imaging technique allowing the absolute quantification of regional cerebral blood flow, which is a surrogate measure of neuronal activity. Methods Subjects with chronic low back and radicular pain and matched healthy normals, undergoing identical procedures, participated in three sessions—a characterization and training session and two arterial spin labeling sessions. In the first imaging session CP (if any) was exacerbated using clinical maneuvers and in the second session noxious heat was applied to the affected leg dermatome, the intensity of which was matched to the pain intensity level of the CP exacerbations for each back pain subject. Results The clinically significant worsening of ongoing CP (≥30%, n=16) was associated with significant regional blood flow increases (6–10 mm/100gr of tissue/min, p<0.01) within brain regions known to activate with experimental pain (somatosensory, prefrontal, and insular cortices) and in other structures observed less frequently in experimental pain studies, such as the superior parietal lobule (part of the dorsal attention network). This effect is specific to changes in ongoing CP as it is observed during worsening CP, but it is not observed after thermal pain application, or in matched, pain-free healthy controls. Conclusions Our findings demonstrate the use of arterial spin labeling to investigate the neural processing of CP, and they are a step forward in the quest for objective biomarkers of the chronic pain experience