Long-term monitoring of the short period SU UMa-type dwarf nova, V844 Herculis

We report on time-resolved CCD photometry of four outbursts of a short-period SU UMa-type dwarf nova, V844 Herculis. We successfully determined the mean superhump periods to be 0.05584(64) days, and 0.055883(3) for the 2002 May superoutburst, and the 2006 April-May superoutburst, respectively. During the 2002 October observations, we confirmed that the outburst is a normal outburst, which is the first recorded normal outburst in V844 Her. We also examined superhump period changes during 2002 May and 2006 April-May superoutbursts, both of which showed increasing superhump period over the course of the plateau stage. In order to examine the long-term behavior of V844 Her, we analyzed archival data over the past ten years since the discovery of this binary. Although photometry is not satisfactory in some superoutbursts, we found that V844 Her showed no precursors and rebrightenings. Based on the long-term light curve, we further confirmed V844 Her has shown almost no normal outbursts despite the fact that the supercycle of the system is estimated to be about 300 days. In order to explain the long-term light curves of V844 Her, evaporation in the accretion disk may play a role in the avoidance of several normal outbursts, which does not contradict with the relatively large X-ray luminosity of V844 Her.Comment: 10 pages, 11 figures, accepted for PAS

Dwarf Novae in the Shortest Orbital Period Regime: I. A New Short Period Dwarf Nova, OT J055717+683226

We report the observation of a new dwarf nova, OT J055717+683226, during its first-ever recorded superoutburst in December 2006. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67+/- 0.03 min (0.05324+/-0.00002 d). The next superoutburst was observed in March 2008. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be ~480 d. The supercycle is much shorter than those of WZ Sge-type dwarf novae having supercycles of >~ 10 yr, which are a major population of dwarf novae in the shortest orbital period regime (<~85 min). Using a hierarchical cluster analysis, we identified seven groups of dwarf novae in the shortest orbital period regime. We identified a small group of objects that have short supercycles, small outburst amplitudes, and large superhump period excesses, compared with those of WZ Sge stars. OT J055717+683226 probably belongs to this group.Comment: 14 pages, 11 figures, accepted for publication in PAS

Passive shoulder abduction range of motion at 3 months postoperatively is the most important prognostic factor for achieving full recovery of range of motion at 6 months after arthroscopic rotator cuff repair

Background: After arthroscopic rotator cuff repair (ARCR), it is crucial for clinicians to predict the functional recovery in the early postoperative period for considering rehabilitation strategies. The aim of this study was to identify the prognostic factors in the early postoperative period for achieving full recovery of range of motion (ROM) at 6 months after ARCR. Methods: This study included 184 patients who underwent ARCR. Patients were divided into the full recovery and nonrecovery groups using the Constant ROM score at 6 months postoperatively. The area under the curve for predicting the full recovery group was calculated for all independent variables such as demographic data, ROM, shoulder functional scores at preoperative and 3 months postoperative using receiver operating characteristic curve analysis. Multivariable logistic regression analysis was then performed using candidate variables with an area under the curve of 0.7 or greater to determine prognostic factors for full recovery at 6 months postoperatively. The same analysis as above was also performed by dividing the patients into groups according to their preoperative ROM. Results: Multivariable logistic regression analysis revealed that preoperative active flexion, 3 months postoperative passive abduction, and internal rotation at 90° abduction ROM were significant prognostic factors of achieving full ROM recovery at 6 months postoperatively. Only passive abduction ROM at 3 months postoperatively was significantly extracted in the preoperative ROM limitation group. Conclusion: This study demonstrated that passive abduction ROM at 3 months postoperatively was a significant prognostic factor of achieving full recovery of ROM at 6 months after ARCR