Event-related potential markers of brain changes in preclinical familial Alzheimer disease.

OBJECTIVES: Event-related potentials (ERPs) can reflect differences in brain electrophysiology underlying cognitive functions in brain disorders such as dementia and mild cognitive impairment. To identify individuals at risk for Alzheimer disease (AD) we used high-density ERPs to examine brain physiology in young presymptomatic individuals (average age 34.2 years) who carry the E280A mutation in the presenilin-1 (PSEN1) gene and will go on to develop AD around the age of 45. METHODS: Twenty-one subjects from a Colombian population with familial AD participated: 10 presymptomatic subjects positive for the PSEN1 mutation (carriers) and 11 siblings without the mutation (controls). Subjects performed a visual recognition memory test while 128-channel ERPs were recorded. RESULTS: Despite identical behavioral performance, PSEN1 mutation carriers showed less positivity in frontal regions and more positivity in occipital regions, compared to controls. These differences were more pronounced during the 200-300 msec period. Discriminant analysis at this time interval showed promising sensitivity (72.7%) and specificity (81.8%) of the ERP measures to predict the presence of AD pathology. CONCLUSIONS: Presymptomatic PSEN1 mutation carriers show changes in brain physiology that can be detected by high-density ERPs. The relative differences observed showing greater frontal positivity in controls and greater occipital positivity in carriers indicates that control subjects may use frontally mediated processes to distinguish between studied and unstudied visual items, whereas carriers appear to rely more upon perceptual details of the items to distinguish between them. These findings also demonstrate the potential usefulness of ERP brain correlates as preclinical markers of AD.

Dynamics of a tunable superfluid junction.

We study the population dynamics of a Bose-Einstein condensate in a double-well potential throughout the crossover from Josephson dynamics to hydrodynamics. At barriers higher than the chemical potential, we observe slow oscillations well described by a Josephson model. In the limit of low barriers, the fundamental frequency agrees with a simple hydrodynamic model, but we also observe a second, higher frequency. A full numerical simulation of the Gross-Pitaevskii equation giving the frequencies and amplitudes of the observed modes between these two limits is compared to the data and is used to understand the origin of the higher mode. Implications for trapped matter-wave interferometers are discussed.

Collective oscillations of an imbalanced Fermi gas: axial compression modes and polaron effective mass.

We investigate the low-lying compression modes of a unitary Fermi gas with imbalanced spin populations. For low polarization, the strong coupling between the two spin components leads to a hydrodynamic behavior of the cloud. For large population imbalance we observe a decoupling of the oscillations of the two spin components, giving access to the effective mass of the Fermi polaron, a quasiparticle composed of an impurity dressed by particle-hole pair excitations in a surrounding Fermi sea. We find m*/m = 1.17(10), in agreement with the most recent theoretical predictions.

Effect of omeprazole on markers of performance in gastric ulcer-free standardbred horses.

REASONS FOR PERFORMING STUDY: A large percentage of performance horses develop gastric ulcers and many of those horses are treated with omeprazole. Unfortunately, no data have been published on the effects of the drug on markers of performance in animals without ulcers. HYPOTHESIS: Omeprazole would alter markers of aerobic and anaerobic performance. METHODS: Ten unfit, healthy, ulcer free, Standardbred mares were administered either control (CON; oral apple sauce, 20 ml) or omeprazole (OP; oral paste, 4 mg/kg bwt s.i.d.) in a random crossover fashion with the investigators blind to the treatment. Treatments were administered for 7 days prior to performing an incremental exercise test (GXT) on a high-speed treadmill. Endoscopic examinations were performed just prior to the trial to verify that the mares were ulcer-free. During the GXT, the mares ran on a treadmill up a 6% grade to measure maximal oxygen consumption (VO2max), run time (RT), velocity at VO2max, maximal velocity (Vmax), packed cell volume (PCV), plasma lactate concentration (LA) and plasma protein concentration (TP). Measurements were recorded at rest, at the end of each 1 min step of the GXT and at 2 and 5 min post GXT. Data were analysed using ANOVA for repeated measures and t tests for paired comparisons. RESULTS: There was no effect (P>0.05) of omeprazole on VO2max; velocity at VO2max; RT; Vmax; 2 min recovery plasma LA. Nor were there any changes (P>0.05) in the relationship between treadmill speed and VO2, PCV, TP, or plasma LA. CONCLUSIONS: Omeprazole does not appear to improve physiological markers of performance in healthy, ulcer free horses. POTENTIAL RELEVANCE: These data may benefit various authorities responsible for deciding administration and timing policies of omeprazole as well as clinicians and horse owners.

Observation of the vacuum Rabi spectrum for one trapped atom.

The transmission spectrum for one atom strongly coupled to the field of a high finesse optical resonator is observed to exhibit a clearly resolved vacuum Rabi splitting characteristic of the normal modes in the eigenvalue spectrum of the atom-cavity system. A new Raman scheme for cooling atomic motion along the cavity axis enables a complete spectrum to be recorded for an individual atom trapped within the cavity mode, in contrast to all previous measurements in cavity QED that have required averaging over 10(3)-10(5) atoms.

Determination of the number of atoms trapped in an optical cavity.

The number of atoms trapped within the mode of an optical cavity is determined in real time by monitoring the transmission of a weak probe beam. Continuous observation of atom number is accomplished in the strong coupling regime of cavity quantum electrodynamics and functions in concert with a cooling scheme for radial atomic motion. The probe transmission exhibits sudden steps from one plateau to the next in response to the time evolution of the intracavity atom number, from N>or=3 to N=2-->1-->0 atoms, with some trapping events lasting over 1 s.

Deterministic generation of single photons from one atom trapped in a cavity.

A single cesium atom trapped within the mode of an optical cavity is used to generate single photons on demand. The photon wave packets are emitted as a Gaussian beam with temporal profile and repetition rate controlled by external driving fields. Each generation attempt is inferred to succeed with a probability near unity, whereas the efficiency for creating an unpolarized photon in the total cavity output is 0.69 +/- 0.10, as limited by passive cavity losses. An average of 1.4 x 10(4) photons are produced by each trapped atom. These results constitute an important step in quantum information science, for example, toward the realization of distributed quantum networking.

Experimental realization of a one-atom laser in the regime of strong coupling.

Conventional lasers (from table-top systems to microscopic devices) typically operate in the so-called weak-coupling regime, involving large numbers of atoms and photons; individual quanta have a negligible impact on the system dynamics. However, this is no longer the case when the system approaches the regime of strong coupling for which the number of atoms and photons can become quite small. Indeed, the lasing properties of a single atom in a resonant cavity have been extensively investigated theoretically. Here we report the experimental realization of a one-atom laser operated in the regime of strong coupling. We exploit recent advances in cavity quantum electrodynamics that allow one atom to be isolated in an optical cavity in a regime for which one photon is sufficient to saturate the atomic transition. The observed characteristics of the atom-cavity system are qualitatively different from those of the familiar many-atom case. Specifically, our measurements of the intracavity photon number versus pump intensity indicate that there is no threshold for lasing, and we infer that the output flux from the cavity mode exceeds that from atomic fluorescence by more than tenfold. Observations of the second-order intensity correlation function demonstrate that our one-atom laser generates manifestly quantum (nonclassical) light, typified by photon anti-bunching and sub-poissonian photon statistics.

State-insensitive cooling and trapping of single atoms in an optical cavity.

Single cesium atoms are cooled and trapped inside a small optical cavity by way of a novel far-off-resonance dipole-force trap, with observed lifetimes of 2-3 s. Trapped atoms are observed continuously via transmission of a strongly coupled probe beam, with individual events lasting approximately 1 s. The loss of successive atoms from the trap N>/=3-->2-->1-->0 is thereby monitored in real time. Trapping, cooling, and interactions with strong coupling are enabled by the trap potential, for which the center-of-mass motion is only weakly dependent on the atom's internal state.

Active client participation: an examination of self-empowerment in HIV/AIDS case management with women.

Case management has become increasingly popular as a means to alleviate the difficulties associated with accessing health care and social services. However, little information exists regarding models of case management specifically intended for work with HIV-positive women. This article explores the practices currently in use at an HIV/AIDS service agency to further define empowering practices employed by case managers working with HIV-positive women. Although a client's active participation in service plan development and delivery is widely regarded as the pathway to empowerment, findings indicate that "active participation" is not so readily defined; empowerment exists on a dynamic continuum with increasing levels of client participation. A model is presented that demonstrates the relationship of particular behaviors to client self-empowerment. Because the needs of clients with HIV/AIDS are continually fluctuating, and because case managers' behaviors will need to adapt accordingly, this model also incorporates the concept of balance as it pertains to HIV/AIDS case management.

Anesthetic and analgesic practices in Avicenna's Canon of Medicine.

Anesthetic and analgesic practices during the Middle Ages and the Renaissance are presented from a translation of the relevant sections of the Canon of Medicine by Avicenna (980-1037) one of the most widely read and authoritative textbooks of the period. Avicenna described tracheotomy, oropharyngeal intubation and a method for clearing upper airway secretions for the treatment of stridor and respiratory distress. He also identified certain plants with pharmacological action such as mandragora or nightshade, opium and henbane and gives various recipes for inducing both anesthesia and analgesia before surgery.

Thrower's fracture: a comparison of two presentations of a rare fracture.

We report two similar rare types of fracture of the lower end of the humerus sustained in fit young adults while throwing a ball. Both cases were seen within 1 week in a busy accident and emergency (A&E) department. The types of fracture in each case are unusual and, in the past, have been attributed to fatigue or to a repetitive strain pattern.

Oxygen free radical activity in experimental colonic carcinoma.

Oxygen free radical activity has been implicated in carcinogenesis through DNA lysis. This study measured chemiluminescence and superoxide dismutase (SOD) inhibition as an index of oxygen free radical activity in azoxymethane-induced colonic carcinoma. After 3 weeks of acclimatization, ten Fisher 344 rats were injected with azoxymethane (7 mg kg-1 week-1) over 10 weeks. All animals were killed at 37 weeks and colonic mucosa (5-25 mg wet weight) was sampled from sites of histologically confirmed gross tumour and sites 3-5 cm distant from tumour as well as from ten paired normal controls. The samples were processed in buffered luminol and chemiluminescence was measured in a luminometer. Each sample was then placed in a solution of SOD for 3 min before a second chemiluminescence estimation. Mean(s.e.m.) chemiluminescence from control mucosal samples decreased from 8.1(1.0) to 3.9(1.1) mV per 100 mg tissue (P < 0.05) after incubation in SOD, suggesting that oxygen free radical activity was being measured. There was an increase to 20.2(0.9) mV per 100 mg in azoxymethane-treated colon remote from tumour and to 53.9(2.1) mV per 100 mg at tumour sites; both were reduced significantly after incubation with SOD to 6.7(0.7) and 11.0(0.8) mV per 100 mg respectively (P < 0.001). Chemiluminescence was significantly increased in azoxymethane-induced colonic carcinoma, both remote from and maximally at the tumour site, suggesting a field change in carcinogenesis associated with oxygen free radical activity.

A season of football injuries.

All rugby and soccer players presenting to the Accident & Emergency department during the football season 1992-1993 (a total of 871) were prospectively studied to compare the injuries sustained in the two sports. The nature and site of injury, treatment required, age, fitness, experience and position of the player, situation giving rise to injury, and medical attention at the grounds were all analysed. The results show that rugby and soccer players had the same number of injuries, and while there were some differences in the nature of the injuries, there was no difference in overall severity. Rugby flankers and soccer goalkeepers are particularly at risk. Competitive matches produce more injuries than training sessions. Experience or fitness did not appear to be a factor and 45% of rugby injuries and 15% of soccer injuries were from school matches. Law changes (e.g. the rugby scrum and the use of gum-shields) have reduced some injuries, but other areas (e.g. jumping for the ball in soccer, rucks and mauls in rugby) also warrant consideration. There was one death, but no spinal cord injuries. Medical attention at the grounds was limited. Rugby injuries, therefore, do not appear to be more numerous or severe than soccer injuries. Law changes have been of benefit but they need to be enforced and perhaps more should be considered. Medical attention at sports grounds could be improved and Registers of injuries kept by the sporting bodies would be of benefit.