Optimal Power Cost Management Using Stored Energy in Data Centers

Since the electricity bill of a data center constitutes a significant portion of its overall operational costs, reducing this has become important. We investigate cost reduction opportunities that arise by the use of uninterrupted power supply (UPS) units as energy storage devices. This represents a deviation from the usual use of these devices as mere transitional fail-over mechanisms between utility and captive sources such as diesel generators. We consider the problem of opportunistically using these devices to reduce the time average electric utility bill in a data center. Using the technique of Lyapunov optimization, we develop an online control algorithm that can optimally exploit these devices to minimize the time average cost. This algorithm operates without any knowledge of the statistics of the workload or electricity cost processes, making it attractive in the presence of workload and pricing uncertainties. An interesting feature of our algorithm is that its deviation from optimality reduces as the storage capacity is increased. Our work opens up a new area in data center power management.Comment: Full version of Sigmetrics 2011 pape

Obesity Does Not Increase Mortality after Emergency Surgery

Objective. The aim of this study is to evaluate the impact of obesity on patient outcomes after emergency surgery. Methods. A list of all patients undergoing emergent general surgical procedures during the 12 months ending in July 2012 was obtained from the operating room log. A chart review was performed to obtain the following data: patient characteristics (age, gender, BMI, and preexisting comorbidities), indication for surgery, and outcomes (pulmonary embolus (PE), deep venous thrombosis (DVT), respiratory failure, ICU admission, wound infection, pneumonia, and mortality). Obesity was defined as a BMI over 25. Comparisons of outcomes between obese and nonobese patients were evaluated using Fischer’s exact test. Predictors of mortality were evaluated using logistic regression. Results. 341 patients were identified during the study period. 202 (59%) were obese. Both groups were similar in age (48 for obese versus 47 for nonobese, ). Obese patients had an increased incidence of diabetes, (27% versus 7%, ), hypertension (52% versus 34%, ), and sleep apnea (0% versus 5%, ). There was a statistically significant increased incidence of postoperative wound infection (obese 9.9% versus nonobese 4.3%, ) and ICU admission (obese 58% versus nonobese 42%, ) among the obese patients. Obesity alone was not shown to be a significant risk factor for mortality. Conclusions. A higher BMI is not an independent predictor of mortality after emergency surgery. Obese patients are at a higher risk of developing wound infections and requiring ICU admission after emergent general surgical procedure

Laparoscopic Management of Delayed Recurrent Intussusception in an Older Child

BACKGROUND: Intussusception is the most common cause of bowel obstruction in infants and children. Although early recurrence is not uncommon, recurrence years later is rare. METHODS: A 13-year-old male with a history of recurrent intussusception at ages 2 and 5 presented with recurrent intussusception 8 years later. The diagnosis was made using computed tomography, and the patient underwent a laparoscopic ileocecectomy with an uneventful postoperative course. RESULTS: The specimen was remarkable for findings of multiple enlarged lymph nodes over the serosal surface of the ileum and the terminal ileum with focal edema, prominent lymphoid hyperplasia and large hemorrhagic areas. CONCLUSION: This case highlights the fact that in a child with a delayed recurrence of intussusception, the presence of a lead point should be suspected, and operative therapy should be strongly considered over hydrostatic reduction. The current management of recurrent intussusception is reviewed and applied to this case

Unilateral Incomplete Bifid Ureter Presenting with Calculus in Right Kidney with Hydronephrosis: A Rare Case Report

an incomplete duplicate ureter to be 18 out of a series of 4215 autopsies studied. Amongst these 2 were the bilaterally incomplete duplicate, 7 were a unilaterally incomplete duplicate and 8 were the unilaterally complete duplicate

Pitch strength of normal and dysphonic voices

Two sounds with the same pitch may vary from each other based on saliency of their pitch sensation. This perceptual attribute is called “pitch strength.” The study of voice pitch strength may be important in quantifying of normal and pathological qualities. The present study investigated how pitch strength varies across normal and dysphonic voices. A set of voices (vowel /a/) selected from the Kay Elemetrics Disordered Voice Database served as the stimuli. These stimuli demonstrated a wide range of voice quality. Ten listeners judged the pitch strength of these stimuli in an anchored magnitude estimation task. On a given trial, listeners heard three different stimuli. The first stimulus represented very low pitch strength (wide-band noise), the second stimulus consisted of the target voice and the third stimulus represented very high pitch strength (pure tone). Listeners estimated pitch strength of the target voice by positioning a continuous slider labeled with values between 0 and 1, reflecting the two anchor stimuli. Results revealed that listeners can judge pitch strength reliably in dysphonic voices. Moderate to high correlations with perceptual judgments of voice quality suggest that pitch strength may contribute to voice quality judgments

Improving the fluorescent probe acridonylalanine through a combination of theory and experiment

Acridonylalanine (Acd) is a useful fluorophore for studying proteins by fluorescence spectroscopy, but it can potentially be improved by being made longer wavelength or brighter. Here, we report the synthesis of Acd core derivatives and their photophysical characterization. We also performed ab initio calculations of the absorption and emission spectra of Acd derivatives, which agree well with experimental measurements. The amino acid aminoacridonylalanine (Aad) was synthesized in forms appropriate for genetic incorporation and peptide synthesis. We show that Aad is a superior Förster resonance energy transfer acceptor to Acd in a peptide cleavage assay and that Aad can be activated by an aminoacyl tRNA synthetase for genetic incorporation. Together, these results show that we can use computation to design enhanced Acd derivatives, which can be used in peptides and proteins

The Peculiar Debris Disk of HD 111520 as Resolved by the Gemini Planet Imager

Using the Gemini Planet Imager (GPI), we have resolved the circumstellar debris disk around HD 111520 at a projected range of ~30-100 AU in both total and polarized $H$-band intensity. The disk is seen edge-on at a position angle of ~165$^{\circ}$ along the spine of emission. A slight inclination or asymmetric warping are covariant and alters the interpretation of the observed disk emission. We employ 3 point spread function (PSF) subtraction methods to reduce the stellar glare and instrumental artifacts to confirm that there is a roughly 2:1 brightness asymmetry between the NW and SE extension. This specific feature makes HD 111520 the most extreme examples of asymmetric debris disks observed in scattered light among similar highly inclined systems, such as HD 15115 and HD 106906. We further identify a tentative localized brightness enhancement and scale height enhancement associated with the disk at ~40 AU away from the star on the SE extension. We also find that the fractional polarization rises from 10 to 40% from 0.5" to 0.8" from the star. The combination of large brightness asymmetry and symmetric polarization fraction leads us to believe that an azimuthal dust density variation is causing the observed asymmetry.Comment: 9 pages, 8 Figures, 1 table, Accepted to Ap

Characterizing 51 Eri b from 1-5 μ\mum: a partly-cloudy exoplanet

We present spectro-photometry spanning 1-5 $\mu$m of 51 Eridani b, a 2-10 M$_\text{Jup}$ planet discovered by the Gemini Planet Imager Exoplanet Survey. In this study, we present new $K1$ (1.90-2.19 $\mu$m) and $K2$ (2.10-2.40 $\mu$m) spectra taken with the Gemini Planet Imager as well as an updated $L_P$ (3.76 $\mu$m) and new $M_S$ (4.67 $\mu$m) photometry from the NIRC2 Narrow camera. The new data were combined with $J$ (1.13-1.35 $\mu$m) and $H$ (1.50-1.80 $\mu$m) spectra from the discovery epoch with the goal of better characterizing the planet properties. 51 Eri b photometry is redder than field brown dwarfs as well as known young T-dwarfs with similar spectral type (between T4-T8) and we propose that 51 Eri b might be in the process of undergoing the transition from L-type to T-type. We used two complementary atmosphere model grids including either deep iron/silicate clouds or sulfide/salt clouds in the photosphere, spanning a range of cloud properties, including fully cloudy, cloud free and patchy/intermediate opacity clouds. Model fits suggest that 51 Eri b has an effective temperature ranging between 605-737 K, a solar metallicity, a surface gravity of $\log$(g) = 3.5-4.0 dex, and the atmosphere requires a patchy cloud atmosphere to model the SED. From the model atmospheres, we infer a luminosity for the planet of -5.83 to -5.93 ($\log L/L_{\odot}$), leaving 51 Eri b in the unique position as being one of the only directly imaged planet consistent with having formed via cold-start scenario. Comparisons of the planet SED against warm-start models indicates that the planet luminosity is best reproduced by a planet formed via core accretion with a core mass between 15 and 127 M$_{\oplus}$.Comment: 27 pages, 19 figures, Accepted for publication in The Astronomical Journa