Anomalous Breaking of Scale Invariance in a Two-Dimensional Fermi Gas.

The frequency of the breathing mode of a two-dimensional Fermi gas with zero-range interactions in a harmonic confinement is fixed by the scale invariance of the Hamiltonian. Scale invariance is broken in the quantized theory by introducing the two-dimensional scattering length as a regulator. This is an example of a quantum anomaly in the field of ultracold atoms and leads to a shift of the frequency of the collective breathing mode of the cloud. In this work, we study this anomalous frequency shift for a two-component Fermi gas in the strongly interacting regime. We measure significant upwards shifts away from the scale-invariant result that show a strong interaction dependence. This observation implies that scale invariance is broken anomalously in the strongly interacting two-dimensional Fermi gas.

Auditory inhibitory gating in medial prefrontal cortex: Single unit and local field potential analysis.

Medial prefrontal cortex is a crucial region involved in inhibitory processes. Damage to the medial prefrontal cortex can lead to loss of normal inhibitory control over motor, sensory, emotional and cognitive functions. The goal of the present study was to examine the basic properties of inhibitory gating in this brain region in rats. Inhibitory gating has recently been proposed as a neurophysiological assay for sensory filters in higher brain regions that potentially enable or disable information throughput. This perspective has important clinical relevance due to the findings that gating is dramatically impaired in individuals with emotional and cognitive impairments (i.e. schizophrenia). We used the standard inhibitory gating two-tone paradigm with a 500 ms interval between tones and a 10 s interval between tone pairs. We recorded both single unit and local field potentials from chronic microwire arrays implanted in the medial prefrontal cortex. We investigated short-term (within session) and long-term (between session) variability of auditory gating and additionally examined how altering the interval between the tones influenced the potency of the inhibition. The local field potentials displayed greater variability with a reduction in the amplitudes of the tone responses over both the short and long-term time windows. The decrease across sessions was most intense for the second tone response (test tone) leading to a more robust gating (lower T/C ratio). Surprisingly, single unit responses of different varieties retained similar levels of auditory responsiveness and inhibition in both the short and long-term analysis. Neural inhibition decreased monotonically related to the increase in intertone interval. This change in gating was most consistent in the local field potentials. Subsets of single unit responses did not show the lack of inhibition even for the longer intertone intervals tested (4 s interval). These findings support the idea that the medial prefrontal cortex is an important site where early inhibitory functions reside and potentially mediate psychological processes.

[Endometrial carcinoma and vaginal ultrasound: studies of the diagnostic validity]. / Endometriumkarzinom und Vaginalsonographie: Untersuchungen zur diagnostischen Validität.

BACKGROUND: Up to now, there has been no effective diagnostic procedure for early diagnosis of endometrial cancer. During recent years, however, study results on transvaginal sonography (TVS) of the endometrium have been published recommending TVS as a screening method for early diagnosis of endometrial cancer in postmenopausal women. OBJECTIVE: The purpose of this study was to determine the sensitivity and specificity of TVS in measuring endometrial thickness and the resulting performance under screening conditions. PATIENTS AND METHODS: Patients with postmenopausal bleeding were included in a prospective blind diagnostic study. Endometrial thickness was measured with TVS before D&C. The histological findings of D&C were used as a control. Sensitivity and specificity were calculated after combining the separately and blindly determined findings. RESULTS: The study comprised 195 patients. Endometrial cancer was diagnosed in 29 of these patients, a prevalence of 15%. The median endometrial thickness was 5.5 mm (0-10 mm) in women with endometrial cancer and 4 mm (0-15 mm) in women without cancer (p > 0.05 Mann-Whitney U-test). For a cut-off > or = 4 mm, the sensitivity is 62% and the specificity is 50%. The sensitivities and specificities for all cut-offs are displayed in a receiver operating characteristic (ROC) curve. The relationship between the positive predictive values and the different prevalences is demonstrated in another curve. Using the results of this and other comparable studies, only very low positive predictive values can be calculated (0.03-1.9%) with prevalences expected under screening conditions (0.02-0.12%). CONCLUSION: Transvaginal sonography is not a useful method in early diagnosis of endometrial cancer.

Do preset per visit payment rates affect home health agency behavior?

This article reports on preliminary impacts during the first year of a demonstration in which home health agencies (HHAs) were paid a prospectively set rate for each Medicare home health visit rendered, rather than being reimbursed for costs. Forty-seven agencies in five States participated. The evaluation compared the experiences of randomly assigned treatment agencies and their patients with those of control agencies and their patients and found no compelling evidence of any demonstration impact on agency cost per visit, the volume of home health services, agency revenue and profit, patient selection and retention, quality of care, or use and cost of Medicare services.