Troubleshooting Time-Dependent Density-Functional Theory for Photochemical Applications: Oxirane

The development of analytic-gradient methodology for excited states within conventional time-dependent density-functional theory (TDDFT) would seem to offer a relatively inexpensive alternative to better established quantum-chemical approaches for the modeling of photochemical reactions. However, even though TDDFT is formally exact, practical calculations involve the use of approximate functionals, in particular the TDDFT adiabatic approximation, whose use in photochemical applications must be further validated. Here, we investigate the prototypical case of the symmetric CC ring opening of oxirane. We demonstrate by direct comparison with the results of high-quality quantum Monte Carlo calculations that, far from being an approximation on TDDFT, the Tamm-Dancoff approximation (TDA) is a practical necessity for avoiding triplet instabilities and singlet near instabilities, thus helping maintain energetically reasonable excited-state potential energy surfaces during bond breaking. Other difficulties one would encounter in modeling oxirane photodynamics are pointed out but none of these is likely to prevent a qualitatively correct TDDFT/TDA description of photochemistry in this prototypical molecule.Comment: 19 pages, 17 figures, submitted to the Journal of Chemical Physic

The X-ray spectrum of the Seyfert I galaxy Markarian 766: Dusty warm absorber or relativistic emission lines?

Competing models for broad spectral features in the soft X-ray spectrum of the Seyfert I galaxy Mrk 766 are tested against data from a 130 ks XMM-Newton observation. A model including relativistically broadened Lyalpha emission lines of O VIII N VII and C VI is a better fit to 0.3-2 keV XMM RGS data than a dusty warm absorber. Moreover, the measured depth of neutral iron absorption lines in the spectrum is inconsistent with the magnitude of the iron edge required to produce the continuum break at 17-18 Angstrom in the dusty warm absorber model. The relativistic emission line model can reproduce the broadband (0.1-12 keV) XMM EPIC data with the addition of a fourth line to represent emission from ionized iron at 6.7 keV and an excess due to reflection at energies above the iron line. The pro le of the 6.7 keV iron line is consistent with that measured for the low-energy lines. There is evidence in the RGS data, at the 3sigma level, of spectral features that vary with source flux. The covering fraction of warm absorber gas is estimated to be 12%. Iron in the warm absorber is found to be overabundant with respect to CNO, compared to solar values

Determination of Anaerobic Threshold by Heart Rate or Heart Rate Variability using Discontinuous Cycle Ergometry

International Journal of Exercise Science 7(1) : 45-53, 2014. The purpose was to determine if heart rate (HR) and heart rate variability (HRV) responses would reflect anaerobic threshold (AT) using a discontinuous, incremental, cycle test. AT was determined by ventilatory threshold (VT). Cyclists (30.6±5.9y; 7 males, 8 females) completed a discontinuous cycle test consisting of 7 stages (6 min each with 3 min of rest between). Three stages were performed at power outputs (W) below those corresponding to a previously established AT, one at W corresponding to AT, and 3 at W above those corresponding to AT. The W at the intersection of the trend lines was considered each metric’s “threshold”. The averaged stage data for Ve, HR, and time- and frequency-domain HRV metrics were plotted versus W. The W at the “threshold” for the metrics of interest were compared using correlation analysis and paired-sample t-test. In all, several heart rate-related parameters accurately reflected AT with significant correlations (p≤0.05) were observed between AT W and HR, mean RR interval (MRR), low and high frequency spectral energy (LF and HR, respectively), high frequency peak (fHF), and HFxfHF metrics’ threshold W (i.e., MRRTW, etc.). Differences in HR or HRV metric threshold W and AT for all subjects were less than 14 W. The steady state data from discontinuous protocols may allow for a true indication of steady-state physiologic stress responses and corresponding W at AT, compared to continuous protocols using 1-2 min exercise stages

Influence of environmental factors on the reproductive cycle of the eared ark Anadara notabilis (Röding, 1798) in Northeastern Venezuela

5 figuras, 2 tablasThe reproductive cycle of the eared ark Anadara notabilis and its relationship with environmental factors was evaluated every 15 days between March 2004 and February 2005 at the northern part of the Peninsula de Araya, Venezuela. Environmental factors measured included temperature, salinity, chlorophyll a, and total seston, including the particulate organic matter and particulate inorganic matter fractions. Adult specimens were collected using a net drag and then randomly selected to estimate wet live biomass and dry biomass of soft body tissues. Gonad samples were processed with histological analysis to determine sex ratio, developmental stages, and variations of follicle size. Reproduction in A. notabilis was continuous throughout the year, with spawning peaks occurring in June and October, coinciding with the lowest water temperatures. In March, September, and November 2004, specimens attained the highest dry biomass values, whereas lowest dry biomass occurred in June and October 2004. Stepwise regression analyses demonstrated that temperature and particulate organic matter values are the main modulators of reproductive events. When temperature decreased, dribble spawning was detected in this species, possibly inducing a survival strategy whereby the spawning period is extended to increase reproductive successPeer reviewe

Solitary Fibrous Tumor of the Lower Leg: A Rare and Difficult Diagnosis

Solitary fibrous tumor (SFT) is a rare neoplasm that commonly originates in the pleura. Extrapleural locations are rare and for this reason sometimes difficult to diagnose. Malignant forms with local recurrence or distant metastases have been reported, also as a consequence of inappropriate treatment. In this article, we report the case of an SFT of the lower leg in a 37-year-old man. Leg SFT is a rare occurrence, and differential diagnosis may be difficult because they can mimic a variety of benign and malignant mesenchymal tumors; immunohistochemical analysis for CD34, CD99, vimentin, and Bcl-2 is necessary. Misdiagnosis carries a significant risk of inadequate removal with subsequent increased risk of recurrence and distant metastases

Freestyle-Like V-Y Flaps of the Eyebrow: A New Outlook and Indication of an Historical Technique

The eyebrow region is of utmost importance for facial movement, symmetry, and the overall cosmetic appearance of the face. Trauma or tumor resection often leave scars that may dislocate the eyebrow producing an alteration both in static symmetry of the face and in the dynamic expressivity. The authors present a technique for eyebrow's defects repair using the remaining eyebrow advancement by means of a "freestyle-like" V-Y flap. In the past two years a total of eight consecutive patients underwent excision of skin lesions in the superciliary region and immediate reconstruction with this technique. On histology, six patients were affected from basal cell carcinomas, one from squamous cell carcinoma, and one from congenital intradermal melanocytic nevus. The pedicle of the flap included perforators from the supratrochlear, supraorbital, or superficial temporalis artery. Advancement of the entire aesthetic subunit that includes the eyebrow using a V-Y perforator flap was performed successfully in all cases achieving full, tension-free closure of defects up to 3.0\u2009cm. "Freestyle-like" V-Y flaps should be considered as a first-line choice for partial defects of the eyebrow. The greater mobility compared to random subcutaneous flaps allows to reconstruct large defects providing an excellent cosmetic result

Intensity-dependent reductions in resting blood pressure following short-term isometric exercise training

To reduce resting blood pressure, a minimum isometric exercise training (IET) intensity has been suggested, but this is not known for short-term IET programmes. We therefore compared the effects of moderate- and low-intensity IET programmes on resting blood pressure. Forty normotensive participants (22.3 ± 3.4 years; 69.5 ± 15.5 kg; 170.2 ± 8.7 cm) were randomly assigned to groups of differing training intensities [20%EMGpeak (~23%MVC, maximum voluntary contraction, or 30%EMGpeak (~34%MVC)] or control group; 3 weeks of IET at 30%EMGpeak resulted in significant reductions in resting mean arterial pressure (e.g. −3.9 ± 1.0 mmHg, P 0.05). Moreover, after pooling all female versus male participants, IET induced a 6.9-mmHg reduction in systolic blood pressure in female participants, but only a 1.5-mmHg reduction in systolic blood pressure in male participants, although the difference was not significant. An IET intensity between 20%EMGpeak and 30%EMGpeak is sufficient to elicit significant resting blood pressure reductions in a short-term training period (3 weeks). In addition, sexual dimorphism may exist in the magnitude of reductions, but further work is required to confirm this possibility, which could be important in understanding the mechanisms responsible