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To assess whether a multimodal opioid-limiting protocol and patient education intervention can reduce postoperative opioid use following transurethral resection of the prostate.This prospective, non-blinded, single-institution, randomized controlled trial (NCT04102566) assigned 50 patients undergoing a transurethral resection of the prostate to either a standard of care control (SOC) or multimodal experimental group (MMG). The intervention included adding ibuprofen to the postoperative pain regimen, promoting appropriate opioid use while hospitalized, an educational intervention, and discharging without opioid prescription. Data regarding demographics, operative data, opioid use, pain scores, and patient satisfaction were compared.A total of 47 patients were included, n = 23 (MMG) and n = 24 (SOC). Demographic and operative findings were similar. Statistical analysis for noninferiority demonstrated non-inferior inpatient pain control (mean pain score 2.5 MMG vs 2.4 SOC, P = 0.0003). The multimodal group used significantly fewer morphine milligram equivalents after discharge (0 vs 4.1, P = 0.04). Inpatient use was reduced but did not reach statistical significance (6.0 vs 9.8, P = 0.2). Mean satisfaction scores with pain control were similar (9.6 MMG vs 9.2 SOC, P = 0.32). No opioid prescriptions were requested after discharge. Adverse events and medication side effects were infrequent and largely similar between groups.Implementation of an opioid-limiting postoperative pain protocol and patient education resulted in no outpatient opioid use while maintaining patient satisfaction with pain control. Eliminating opioids following a common urologic procedure will decrease risk of opioid-related adverse events and have a positive downstream impact.

Objectives To assess clinically asymptomatic infants with single-ventricle physiology (SVP) for sleep-disordered breathing (SDB) in the supine and car seat positions using polysomnography. Polysomnography results also were compared with results of a standard Car Seat Challenge to measure the dependability of the standard Car Seat Challenge. Study design This was an observational study of 15 infants with SVP. Polysomnography data included Obstructive Index, Central Index, Arousal Index, Apnea Hypopnea Index, and sleep efficiency. Polysomnography heart rate and oxygen saturation data were used to compare polysomnography with the standard Car Seat Challenge. Results Polysomnography demonstrated that all 15 infants had SDB and 14 had obstructive sleep apnea (Obstructive Index ≥1/hour) in both the supine and car seat positions. Infants with SVP had a statistically significant greater median Obstructive Index in the car seat compared with supine position (6.3 vs 4.2; P = .03), and median spontaneous Arousal Index was greater in the supine position compared with the car seat (20.4 vs 15.2; P = .01). Comparison of polysomnography to standard Car Seat Challenge results demonstrated 5 of 15 (33%) of infants with SVP with abnormal Obstructive Index by polysomnography would have passed a standard Car Seat Challenge. Conclusions Infants with SVP without clinical symptoms of SDB may be at high risk for SDB that appears worse in the car seat position. The standard Car Seat Challenge is not dependable in the identification of infants with SVP and SDB. Further studies are warranted to further delineate its potential impact of SDB on the clinical outcomes of infants with SVP.

Introduction:Previous studies examining patients with equivocal renal scans performed before robotic assisted pyeloplasty for ureteropelvic junction obstruction have shown conflicting resul...

Introduction: In this quality initiative we assessed whether providing surgeons with the American Urological Association guideline regarding intravesical mitomycin C at the time of surgery ...

To more accurately examine the rate of urinary tract infection following onabotulinumtoxinA injection of the bladder we systematically reviewed the literature for definitions of urinary tract infection in studies of onabotulinumtoxinA injections. We assessed the studies for consistency with guideline statements defining urinary tract infections.We systematically reviewed the literature by querying MEDLINE® and Embase®. We included original studies on adult patients with idiopathic overactive bladder and/or neurogenic detrusor overactivity who underwent cystoscopy with onabotulinumtoxinA injection and in whom urinary tract infection was a reported outcome.We identified 299 publications, of which 50 met study inclusion criteria. In 27 studies (54%) urinary tract infection diagnostic criteria were defined with a total of 10 definitions among these studies. None of the overactive bladder studies used a definition which met the EAU (European Association of Urology) criteria for urinary tract infection. Only 2 of the 10 studies on patients with neurogenic bladder used a urinary tract infection definition consistent with the NIDRR (National Institute on Disability and Rehabilitation Research) standards.Definitions of urinary tract infection are heterogeneous and frequently absent in the literature on onabotulinumtoxinA to treat overactive bladder and/or neurogenic bladder. Given the potential for post-procedure urinary symptoms in this setting, explicit criteria are imperative to establish the true urinary tract infection rate following treatment with onabotulinumtoxinA.

Objective To review the pioneering contributions of Dr. Robert Gibbons of Virginia Mason Medical Center to the evolution and development of the modern ureteral stent. Methods We reviewed Dr. Gibbons' extensive work through primary sources, including interviews, projector slides, radiology images, stent prototypes, his personal writings, and archived documents. In addition, we performed a review of historical texts and manuscripts describing important innovations in the development of the ureteral stent. Results In 1972, motivated by a desire to provide his patients with a long-term alternative to open nephrostomy and inspired by Drs. David Davis and Paul Zimskind, who in 1967 had described the use of indwelling ureteral silicone tubing, Dr. Gibbons began to experiment with modifications to improve upon existing stents. To address distal migration, Dr. Gibbons added “wings” that collapsed as the stent was advanced and expanded once in proper position to secure the stent in place. Barium was embedded into the proximal tip to facilitate radiographic visualization. A flange was added to the distal end, preventing proximal migration and minimizing trigonal irritation, and a tail was attached to aid in stent removal. The result was the original Gibbons stent, the first commercially available ureteral stent, and the establishment of Current Procedural Terminology code 52332, still used today. Conclusion The ureteral stent is a fundamental component of urologic practice. In developing the Gibbons stent, Dr. Gibbons played a pivotal role in addressing the challenge of internal urinary diversion particularly for those who needed long-term management. Urologists and the patients they serve owe Dr. Gibbons and other surgeon-inventors a debt of gratitude for their innovative work.

Marginalized zero-inflated count regression models have recently been introduced for the statistical analysis of dental caries indices and other zero-inflated count data as alternatives to traditional zero-inflated and hurdle models. Unlike the standard approaches, the marginalized models directly estimate overall exposure or treatment effects by relating covariates to the marginal mean count. This article discusses model interpretation and model class choice according to the research question being addressed in caries research. Two data sets, one consisting of fictional dmft counts in 2 groups and the other on DMFS among schoolchildren from a randomized clinical trial comparing 3 toothpaste formulations to prevent incident dental caries, are analyzed with negative binomial hurdle, zero-inflated negative binomial, and marginalized zero-inflated negative binomial models. In the first example, estimates of treatment effects vary according to the type of incidence rate ratio (IRR) estimated by the model. Estimates of IRRs in the analysis of the randomized clinical trial were similar despite their distinctive interpretations. The choice of statistical model class should match the study's purpose, while accounting for the broad decline in children's caries experience, such that dmft and DMFS indices more frequently generate zero counts. Marginalized (marginal mean) models for zero-inflated count data should be considered for direct assessment of exposure effects on the marginal mean dental caries count in the presence of high frequencies of zero counts.

Objective To assess the impact of presenting symptom or incidental finding on symptomatic and radiographic outcomes after robotic-assisted pyeloplasty (RAP). Methods We retrospectively reviewed the records of 143 patients at our institution who received pyeloplasty from 2001-2017. Patients without both pre- and postoperative radiographic data were excluded. Patients were grouped by primary presenting symptom into either pain at presentation (pain) or nonpain primary presenting symptom, including incidental findings (nonpain). Primary outcomes were persistence of postoperative symptoms and improvement in diuretic renogram half-times. Results The study inclusion criteria was met by 105 patients. Pain was the most common presenting symptom (70.0%), followed by incidental finding (10.5%), infection (7.6%), hematuria (4.8%), hypertension (2.8%), elevated creatinine (2.8%), and nausea (1.0%). Patients with nonpain presentations were significantly more likely to have postoperative symptoms (P = .04), and less likely to improve on diuretic renogram (P = .03). Incidental presentation was found to be associated with greater likelihood of persistent postoperative symptoms compared with other presentations (36.3% vs 8.5%, P = .02). Conclusion Ureteropelvic junction obstruction (UPJO) patients presenting with pain, experience better symptom and radiographic improvement following RAP compared with patients presenting without pain. Incidental UPJO was the most common nonpain presentation and is associated with less symptomatic and radiographic benefit after RAP. These findings will help reconstructive urologists counsel patients with UPJO regarding outcomes of RAP.

The Methodist movement stands on a bridge. We maintain a sometimes tenuous connection with many of the traditions and ritual forms of the Western Catholic tradition, while also entertaining the inn...

Shared decision making (SDM) is widely encouraged by both the American Urological Association and Choosing Wisely for prostate cancer screening. Implementation of SDM is challenging secondary to time constraints and competing patient priorities. One strategy to mitigate the difficulties in implementing SDM is to utilize a decision aid (DA). Here we evaluate whether a DA improves a patient's prostate cancer knowledge and affects prostate-specific antigen (PSA) screening rates.Patients were randomized to usual care (UC), DA, or DA + SDM. Perception of quality of care was measured using the Consumer Assessment of Healthcare Providers and Systems (CAHPS) survey. Outcomes were stratified by long term provider relationship (LTPR,3 years) versus short term provider relationship (STPR,3 years). Knowledge of prostate cancer screening and the decision regarding screening were assessed. Groups were compared using ANOVA and logistic regression models.A total of 329 patients were randomized. Patients in the DA + SDM arm were significantly more likely to report discussing the implication of screening (33% DA + SDM, 22% UC, 16% DA, p = 0.0292) and answered significantly more knowledge questions correctly compared to the UC arm (5.03 versus 4.46, p = 0.046). However, those in the DA arm were significantly less likely to report that they always felt encouraged to discuss all health concerns (72% DA, 78% DA + SDM, 87% UC, p = 0.0285). Interestingly, STPR patients in the DA arm were significantly more likely to undergo PSA-based prostate cancer screening (41%) than the UC arm (8%, p = 0.019). This effect was not observed in the LTPR group.Providing patients a DA without a personal interaction resulted in a greater chance of undergoing PSA-based screening without improving knowledge about screening or understanding of the consequences of this decision. This effect was exacerbated by a shorter term provider relationship. With complex issues such as the decision to pursue PSA-based prostate cancer screening, tools cannot substitute for direct interaction with a trusted provider.

Genital dermatology represents a challenge to many providers. Though dermatologic lesions involving the genitalia may present to any of a number of practices, ranging from primary care to urology, gynecology, and dermatology, few training programs provide significant training regarding the diagnosis and management of genital dermatologic lesions. The purpose of this review is to provide urologists with an overview of common genital dermatological lesions that may be encountered in a clinic. The review also provides a guide to how to approach these conditions. This manuscript summarizes the most common categories of genital dermatologic lesions, starting with normal variants and progressing to a review of contagious conditions, premalignant lesions, and malignant lesions. In cases in which a lesion does not definitively belong to one of these categories, an algorithmic approach to making a diagnosis may be helpful to narrow the differential diagnosis. The most common benign genital growths include cysts, syringomas, seborrheic keratosis, pearly papules, and Fordyce spots. Contagious lesions, such as herpes, syphilis, scabies, or molluscum contagiosum, should be treated immediately before complications or transmission can occur. Inflammatory genital lesions are very diverse in etiology and presentation but are the most common genital lesions in urological clinical practice. This category of lesions can be approached by dividing them into non-erythematous and erythematous (scaling and non-scaling) lesions. Given the potential evolution of the challenging category of premalignant genital lesions, proper recognition and early biopsy play an important role. Premalignant lesions can be broadly classified into two categories: those not related to HPV infection and those that are related to HPV, including erythroplasia of Queyrat (EQ), Bowen’s disease, Bowenoid papulosis, vulvar intraepithelial neoplasia (VIN), and giant condyloma. Herein, contemporary nomenclature and proper evaluation and management of premalignant lesions are reviewed which provide safe and efficacious outcomes for patients. Finally, malignant genital lesions, though rare, must be recognized early and addressed correctly. Squamous cell carcinoma represents 95% of penile and approximately 90% of vulvar and vaginal malignancies, and diagnosis and management can be challenging and require proper referral to an oncologist. Genital dermatology is a challenging field marked by diagnostic difficulty and management challenges. This manuscript provides an overview of genitourinary dermatologic lesions in an effort to provide clinicians with a framework with which to approach the evaluation of these various conditions that will facilitate proper consideration of the differential diagnoses and help the urologist distinguish between normal, benign, premalignant, and malignant lesions.

Post-learning sleep is beneficial for human memory. However, it may be that not all memories benefit equally from sleep. Here, we manipulated a spatial learning task using monetary reward and performance feedback, asking whether enhancing the salience of the task would augment overnight memory consolidation and alter its incorporation into dreaming. Contrary to our hypothesis, we found that the addition of reward impaired overnight consolidation of spatial memory. Our findings seemingly contradict prior reports that enhancing the reward value of learned information augments sleep-dependent memory processing. Given that the reward followed a negative reinforcement paradigm, consolidation may have been impaired via a stress-related mechanism.

Background In this article, the authors present evidence-based clinical recommendations regarding the use of nonfluoride caries-preventive agents. The recommendations were developed by an expert panel convened by the American Dental Association (ADA) Council on Scientific Affairs. The panel addressed several questions regarding the efficacy of nonfluoride agents in reducing the incidence of caries and arresting or reversing the progression of caries. Types of Studies Reviewed A panel of experts convened by the ADA Council on Scientific Affairs, in collaboration with ADA Division of Science staff, conducted a MEDLINE search to identify all randomized and nonrandomized clinical studies regarding the use of nonfluoride caries-preventive agents. Results The panel reviewed evidence from 50 randomized controlled trials and 15 nonrandomized studies to assess the efficacy of various nonfluoride caries-preventive agents. Clinical Implications The panel concluded that certain non-fluoride agents may provide some benefit as adjunctive therapies in children and adults at higher risk of developing caries. These recommendations are presented as a resource for dentists to consider in the clinical decision-making process. As part of the evidence-based approach to care, these clinical recommendations should be integrated with the practitioner's professional judgment and the patient's needs and preferences. (The full report can be accessed at "http://ebd.ada.org/ClinicalRecommendations.aspx".)

The ultimate purpose of both dental industry and dental education is to improve the oral health of the public. This report provides background information on the different roles and objectives of the dental industry and dental education communities, the different operating environment of each sector and also areas of common interest where collaboration will be of mutual benefit. The report addresses five areas for potential collaboration between the dental industry and the dental education communities: 1. Contribution to joint activities. 2. Effectiveness and efficiency. 3. Workforce needs. 4. Middle- and low-income countries. 5. The future of International Federation of Dental Educators and Associations (IFDEA). The traditional areas of support and their limitations that have been provided by industry are outlined in the report and some new approaches for collaboration are considered. Industry-based research has been an important factor in developing new products and technologies and in promoting oral health. However there is a need to facilitate the introduction of these developments at an early stage in the education process. Industry has to operate in an efficient manner to remain competitive and maximise its returns and therefore survive. The academic sector operates in a different environment and under different governance structures; although some trends are noted towards adoption of greater efficiency and financial accountability similar to industry. Opportunities to jointly develop best business practices should be explored. Industry has responded well to the oral health needs of the public through the development of new products and technologies. The education community needs to respond in a similar way by examining different healthcare delivery models worldwide and developing programmes to train members of the dental team to cater for future needs and demands of communities in different regions of the world. The reputation of industry-based scientists and clinicians is high, and their role in contributing to the dental education process in practical ways needs to be explored and further developed. Closer relationships between industry scientists and faculty and students could assist industrys need and desire to develop new technologies for the broader dental care system. The corporate sector can play a key role in the future success of IFDEA by providing support and expertise in developing areas such as regional leadership institutes, a Global Faculty and Network and in collaborating in developing continuing education programmes as well as involvement in its governance. Thirteen recommendations are made in the report. These are considered to be important initial steps in developing the already strong relationship between the education and corporate sectors. Partnership and collaborating more effectively along the lines suggested should, almost certainly, generate mutually beneficial outcomes, whilst serving over the long term to elevate the publics oral health status on a global basis.

F. Aharonian, A. Akhperjanian, M. Beilicke, K. Bernlohr, H.-G. Borst, H. Bojahr, O. Bolz, T. Coarasa, J. Contreras, J. Cortina, S. Denninghoff, V. Fonseca, M. Girma, N. Gotting, G. Heinzelmann, G. Hermann, A. Heusler, W. Hofmann, D. Horns, I. Jung, R. Kankanyan, M. Kestel, A. Kohnle, A. Konopelko, D. Kranich, H. Lampeit, M. Lopez, E. Lorenz, F. Lucarelli, O. Mang, D. Mazin, H. Meyer, R. Mirzoyan, A. Moralejo, E. Ona-Wilhelmi, M. Panter, A. Plyasheshnikov, G. Puhlhofer, R. de los Reyes, W. Rhode, J. Ripken, G. P. Rowell, V. Sahakian, M. Samorski, M. Schilling, M. Siems, D. Sobzynska, W. Stamm, M. Tluczykont, V. Vitale, H. J. Volk, C. A. Wiedner, and W. Wittek

The Crab supernova remnant has been observed regularly with the stereoscopic system of 5 imaging air Cherenkov telescopes that was part of the High Energy Gamma Ray Astronomy (HEGRA) experiment. In total, close to 400 hours of useful data have been collected from 1997 until 2002. The spectrum extends up to energies of 80 TeV and is well matched by model calculations in the framework of inverse Compton scattering of various seed photons in the nebula including for the first time a recently detected compact emission region at mm-wavelengths. The observed indications for a gradual steepening of the energy spectrum in data is expected in the inverse Compton emission model.The average magnetic field in the emitting volume is determined to be $(161.6\pm0.8mathrm{stat}\pm18_\mathrm{sys}) \mu$G. The presence of protons in the nebula is not required to explain the observed flux and upper limits on the injected power of protons are calculated being as low as 20 % of the total spin down luminosity for bulk Lorentz factors of the wind in the range of $10^4-10^6$.The position and size of the emission region have been studied over a wide range of energies. The position is shifted by 13\arcsec to the west of the pulsar with a systematic uncertainty of 25\arcsec. No significant shift in the position with energy is observed. The size of the emission region is constrained to be less than 2\arcmin at energies between 1 and 10 TeV. Above 30 TeV the size is constrained to be less than 3\arcmin.No indications for pulsed emission has been found and upper limits in differential bins of energy have been calculated reaching typically 1-3 % of the unpulsed component., Comment: 53 pages, 12 figures. Accepted for publication in Astrophysical Journal

The history of clinical trials would include events in 1747 on board the Salisbury, a British Navy vessel at sea with 12 seamen critically ill with scurvy. Involving these 12 sailors in a study, an officer on board by the name of Lind evaluated six potential treatments for scurvy, and rapidly reached the conclusion that daily consumption of citrus fruits returned the men fit for duty in approximately six days (Bull, 1959). The concept of experimental randomization was first developed by Sir R.A. Fisher (1925, 1926), and the method was introduced to medical research via a study of tuberculosis treatment by Amberson and co-workers (1931), who randomized 24 TB patients into two groups, one to receive the experimental therapy, the other serving as the control. Amberson et al. also incorporated the concept of blinding into their study. Sir Austin Bradford Hill codified and built on the principles of scientific experimentation developed by Fisher, and introduced the use of random numbers in the allocation of patients in the British Medical Research Council (1948) study of the effect of streptomycin in the treatment of tuberculosis (Daniels and Hill, 1952; Hill, 1952). The first applications of clinical trial methodology for testing interventions on dental, oral, and maxillofacial diseases and conditions are more difficult to determine. For dental caries prevention, however, Chilton and Fertig (1958) and Slack and Martin (1964) were certainly among the early caries clinical trial pioneers. As clinical trials have come into the mainstream of clinical research in medicine and dentistry, a great deal of developmental work has focused on their methodological enhancement. The most successful of these efforts have come from fruitful, ongoing collaborations among clinician investigators, biostatisticians, data management specialists, biomedical ethicists, and others with an academic interest in clinical trial design and utilization. During the past 25 years, the emergence of systematic reviews and the evidence-based medicine (EBM) movement have also contributed significantly to the increasing reliance on randomized clinical trial outcomes for the advancement of better clinical practice (Richards et al., 1997; Straus and Sackett, 1998; www.cochrane.org/cochrane/ccbroch.htm#BDL, 2002).

The array of 5 imaging atmospheric y Cerenkov telescopes (IACTs) deployed at La Palma (Canary Islands), and operated by the HEGRA (High Energy Gamma Ray Astronomy) collaboration, was used for observations of the Monoceros Loop SNR region for a total of about 120 hrs and 20 hrs in ON-source and OFF-source mode, respectively. The giant molecular cloud Rosette Nebula appears in the sky region, close to the south-east part of the SNR rim. Using the HEGRA system of IACTs of rather large field of view (4.3 degree in diameter), we have mapped the extended sky region of 3 ◦ × 3 ◦ associated with the Monoceros SNR/Rosette Nebula, which is centered towards the hard spectrum X-ray point source SAX J0635+533. The EGRET unidentified source of diffuse γ-ray emission (3EG J0634+0521) observed in the energy range between 100 MeV-10 GeV, was effectively in the field of view of our present observations. Also, the GeV source GeV J0633+0645 was within the available field of view. The performance of the IACTs array reveals an energy threshold of 500 GeV and an angular resolution of 0.1 ◦ for γ-rays. In what follows, we present the result of the data analysis and its physical interpretation.

In the first months of 2001 the AGN Mkn 421 showed highly variable, strong TeV activity at flux levels frequently exceeding 1 Crab. Here we present the light curve and energy spectrum of Mkn 421 as measured with the HEGRA stand alone telescope CT1. Around 30% of the data were taken under moonlight conditions. The spectrum shows a significant exponential energy cuto at around 3.4 TeV. The results from the dark night- and the moon data are in excellent agreement with each other. A significant spectral shape variation depending on the flux level has been found. The TeV light curve is also found to be highly correlated with the X-ray light curve of the RXTE/ ASM satellite, showing no significant time lag larger than 0.2 d. The derived correlation coecient of 0.83 corresponds to a 5:2 significance.

TeV γ-rays from the BL Lac object 1ES 1959+650 have been measured during the years 2000 and 2001 with a significance of 5.2 σ at a value of 5.3% of the Crab flux and in May 2002 during strong outbursts with >23 σ at a flux level of up to 2.2 Crab, making 1ES 1959+650 the TeV Blazar with the third best event statistics. The deep observation of 197.4 h has been performed with the HEGRA stereoscopic system of 5 imaging atmospheric Cherenkov telescopes (IACT system). 1ES 1959+650 is located at a redshift of z = 0.047, providing an intermediate distance between the nearby Blazars Mkn 421 and Mkn 501, and the much more distant object H1426+428. This makes 1ES 1959+650 an important member of the class of TeV Blazars in view of the absorption of TeV photons by the diffuse extragalactic background radiation (DEBRA). The differential energy spectrum of 1ES 1959+650 during the flares can be fitted by a power law with a spectral index of 2.83 ± 0.14stat ± 0.08sys or by a power law with an exponential cut-off at (4.2 +0.8 −0.6 stat ± 0.9sys) TeV and a spectral index of 1.83 ± 0.15stat ± 0.08sys. The low state differential energy spectrum obtained with lower statistics can be described by a pure power law with a spectral index of 3.18 ± 0.17stat ± 0.08sys.

For the first time an excess of photons above an energy threshold of 730 GeV from the giant radio galaxy M87 has been measured at a significance level above 4 sigma. The data have been taken during the years 1998 and 1999 with the HEGRA stereoscopic system of 5 imaging atmospheric Cherenkov telescopes. The excess of 107.4 +- 26.8 events above 730 GeV corresponds to an integral flux of 3.3% of the Crab flux or N_gamma(E > 730 GeV) = (0.96 +- 0.23) * 10^(-12) phot.cm^(-2)s^(-1). M87 is located at the center of the Virgo cluster of galaxies at a relatively small redshift of z = 0.00436 and is a promising candidate among the class of giant radio galaxies for the emission of TeV gamma-radiation. The detection of TeV gamma-rays from M87 -- if confirmed -- would establish a new class of extragalactic source in this energy regime since all other AGN detected to date at TeV energies are BL Lac type objects., 5 pages, 3 figures, refereed version, corrected calculation of energy flux

Using data from the HEGRA air shower array, taken in the period from April 1998 to March 2000, upper limits on the ratio Iγ/ICR of the diffuse photon flux Iγ to the hadronic cosmic ray flux ICR are determined for the energy region 20–100 TeV. The analysis uses a gamma–hadron discrimination which is based on differences in the development of photon- and hadron-induced air showers after the shower maximum. A method which is sensitive only to the non-isotropic component of the diffuse photon flux yields an upper limit of Iγ/ICR (at 54 TeV)

A search for potential point sources of very high energy gamma rays has been carried out on the data taken simul- taneously by the HEGRA AIROBICC and Scintillator arrays from August 1994 to March 2000. The list of sought sources includes supernova remnants, pulsars, AGNs and binary systems. The energy threshold is around 15 TeV. For the Crab Nebula, a modest excess of 2.5 standard deviations above the cosmic ray background has been observed. Flux upper limits (at 90% c.l.) of around 1.3 times the flux of the Crab Nebula are obtained, in average, for the candidate sources. A dierent search procedure has been used for an all-sky search which yields absolute flux upper limits between 4 and 9crabs depending on declination, in the band from= 0t o= 60.

The detection of TeV -rays from the blazar H 1426+428 at an integral flux level of (4 2stat 1syst) 10 12 erg cm 2 s 1 above 1 TeV with the HEGRA imaging atmospheric Cherenkov telescope system is reported. H 1426+428 is located at a redshift of z = 0.129, which makes it the most distant source detected in TeV -rays so far. The TeV radiation is expected to be strongly absorbed by the diuse extragalactic background radiation (DEBRA). The observed energy spectrum of TeV photons is in good agreement with an intrinsic power law spectrum of the source/ E 1:9 corrected for DEBRA absorption. Statistical errors as well as uncertainties about the intrinsic source spectrum, however, do not permit strong statements about the density of the DEBRA infrared photon eld.

Sometimes there is interest in a dichotomized outcome indicating whether a count variable is positive or zero. Under this scenario, the application of ordinary logistic regression may result in efficiency loss, which is quantifiable under an assumed model for the counts. In such situations, a shared-parameter hurdle model is investigated for more efficient estimation of regression parameters relating to overall effects of covariates on the dichotomous outcome, while handling count data with many zeroes. One model part provides a logistic regression containing marginal log odds ratio effects of primary interest, while an ancillary model part describes the mean count of a Poisson or negative binomial process in terms of nuisance regression parameters. Asymptotic efficiency of the logistic model parameter estimators of the two-part models is evaluated with respect to ordinary logistic regression. Simulations are used to assess the properties of the models with respect to power and Type I error, the latter investigated under both misspecified and correctly specified models. The methods are applied to data from a randomized clinical trial of three toothpaste formulations to prevent incident dental caries in a large population of Scottish schoolchildren.

The elemental depletion of MCrAlY coatings on IN 738 LC by interdiffusion and formation of Al 2 O 3 scales has been studied. Exposure experiments on a NiCoCrAlYRe coating with 12% Al and CoNiCrAl(8%)Y coating at 1000°C up to 10000 hours have been carried out. The total β-phase depletion and consequently the decrease of the Al content of the coating and the damage of the base material by interdiffusion was determined. Additionally the development of Kirkendall pores was found to increase with time. Of special interest were investigations on the interdiffusion behaviour on different elements after two different preheating temperatures (- 600°C, - 900°C) during the coating process itself. After the normal heat treatment for IN 738 LC, the element distribution in the coating and base material was unchanged at 600°C, but exhibited a 50μm interdiffusion zone at 900°C. With increasing preheating temperatures the adhesion strength is getting stronger and reach values larger than 200 MPa for a preheating temperature of 900°C. Therefore the bond strength is mainly controlled by the preheating prior to application of the coating.

In this paper we present the results of simultaneous observations of the TeV blazar Markarian 421 (Mrk 421) at X-ray and TeV Gamma-ray energies with the Rossi X-Ray Timing Explorer (RXTE) and the stereoscopic Cherenkov Telescope system of the HEGRA (High Energy Gamma Ray Astronomy) experiment, respectively. The source was monitored from February 2nd to February 16th and from May 3rd to May 8th, 2000. We discuss in detail the temporal and spectral properties of the source. Remarkably, the TeV observations of February 7th/8th showed statistically significant evidence for substantial TeV flux variability on 30 min time scale. We show the results of modeling the data with a time dependent homogeneous Synchrotron Self-Compton (SSC) model. The X-ray and TeV gamma-ray emission strengths and energy spectra together with the rapid flux variability strongly suggest that the emission volume is approaching the observer with a Doppler factor of 50 or higher. The different flux variability time scales observed at X-rays and TeV Gamma-rays indicate that a more detailed analysis will require inhomogeneous models with several emission zones.

Using the HEGRA system of imaging atmospheric Cherenkov telescopes, a region of the Galactic plane ( 10

Yttria-stabilized zirconia (YSZ) powders from different manufacturers have been used to prepare atmospheric plasma-sprayed (APS) ceramic coatings with different porosity levels. While the particle morphology of the different powders was similar, the amount of impurities, especially silica, was different, varying between 100 and 1500 ppm. APS coatings were removed from the substrates and the porosity distribution was measured by mercury porosimetry. Typically porosity levels between 10 and 15% have been used. Free-standing coatings were investigated in the dilatometer during long-term (>50 h) annealing at 1200°C. Additionally, the coefficient of thermal expansion was determined from expansion during heating. It turned out that the higher porosity levels, as well as the high impurity levels, led to a significant increase in the sintering rate of the coating during high-temperature annealing. A linear relationship between the total shrinkage after 60 h and the porosity, as well as the silica content, was used to describe the influence of the investigated parameters on the sintering behaviour in a more quantitative way.

For distant extragalactic sources of gamma-rays in the PeV (10 15 eV) energy range, interactions of the gamma rays with intergalactic diuse radiation elds will initiate a pair cascade. Depending on the magnetic elds in the vicinity of the source, the cascade can either result in an isotropic halo around an initially beamed source, or remain more or less collimated. Data recorded by the HEGRA system of imaging atmospheric Cherenkov telescopes are used to derive limits on the halo flux from the AGN Mrk 501. This is achieved by comparing the angular distribution of TeV gamma-rays during the 1997 burst phase { where direct photons should dominate { with the distribution during the 1998/99 quiescent state, where a steady-state halo contribution should be most pronounced. The results depend on the assumptions concerning the angular distribution of the halo; limits on the halo flux within 0:5 to 1 from the source range between 0.1% and 1% of the peak burst flux.

During 1997, the BL Lac object Mkn 501 went into an extraordinary state of high X-ray and TeV gamma-ray activity, lasting more than 6 months. In this paper we report on the TeV emission characteristics of the source in the subsequent years of 1998 and 1999 as measured with the Stereoscopic Cherenkov Telescope System of HEGRA (La Palma, Canary Islands). Our observations reveal a 1998-1999 mean emission level at 1 TeV of 1/3 of the flux of the Crab Nebula, a factor of 10 lower than during the year of 1997. A dataset of 122 observations hours with the HEGRA telescope system makes it possible to assess for the first time the Mkn 501 TeV energy spectrum for a mean flux level substantially below that of the Crab Nebula with reasonable statistical accuracy. Excluding the data of a strong flare, we find evidence that the 1998--1999 low-flux spectrum is substantially softer (by 0.44+-0.1(stat) in spectral index) than the 1997 time averaged spectrum. The 500 GeV to 10 TeV energy spectrum can well be described by a power law model with exponential cutoff: dN/dE ~ E^(-alpha) exp(-E/E0) with alpha=2.31+-0.22(stat), and E0=5.1 (-2.3+7.8)(stat) TeV. Within statistical accuracy, also a pure power law model gives an acceptable fit to the data: dN/dE ~ E^(-Gamma) with Gamma=2.76+-0.08(stat). After presenting the 1998-1999 TeV characteristics of the source we discuss the implications of the results., Accepted for publication in The Astrophysical Journal, Part 1, on August 4th, 2000

Thin layers restructured by surface melting to approximately 30-μm depth on MCrAlY coatings were produced using the large-area pulsed electron-beam GESA facility. With a beam diameter of up to 10 cm, it is possible to treat large surface areas, with just a few overlapping electron beam pulses. The high cooling rates lead to nanocrystalline structures at the sample surface. Their oxidation properties were studied at 950°C in air. As the surface treatment leads to smooth surfaces, with an RA

The failure mechanisms of thermal barrier coating (TBC) systems applied on gas turbine blades and vanes are investigated using thermomechanical fatigue (TMF) tests and finite element (FE) modeling. TMF tests were performed at two levels of applied mechanical strain, namely five times and three times the critical in-service mechanical strain of an industrial gas turbine. TMF testing under the higher mechanical strain of air plasma-sprayed (APS) and electron beam–physical vapor deposition (EB-PVD) coated samples showed that both systems failed after a similar number of cycles by cracks that initiated at the bond coat/thermally grown oxide (TGO) interface and propagated through the bond coat to the substrate. When the applied mechanical strain was decreased, cracking of the bond coat in EB-PVD coated systems was suppressed, the life of the coated system increased significantly and delamination of the top-coat was observed. A subsequent FE analysis showed that, by subjecting the system to the higher mechanical strain, significant tensile stresses develop in the TGO and the bond coat that are thought to be responsible for the observed crack initiation and propagation. The FE model also predicts that cracking initiates at specific geometric features of the rough interface of a PS coated system, which was confirmed by metallographic examination of failed samples. The decrease of the applied mechanical strain and hence of the developed stresses led to the suppression of failure by bond coat cracking and activate delamination. These results outline the importance of designing TMF tests and selecting the appropriate mechanical loading in order to accelerate testing and still trigger the same failure mechanisms as observed in-service.

A new method is presented for an absolute energy calibration of imaging atmospheric Cherenkov telescopes as a whole instrument at all relevant wave- lengths. For this study the Cherenkov telescope #1 of the HEGRA 1 experiment was used. The calibration was carried out by detecting the light of dierent selected stars during one night. From the data a simple linear correlation was derived between the anode current of the Cherenkov camera photomultiplier tubes and the incident photon flux. This result is important for the imaging air Cherenkov technique in several aspects: The method enables to determine the response function of Cherenkov telescopes in the energetic range of Cherenkov light quickly and reliably. Therefore it can be used as an atmospheric calorimeter by measuring the absolute integrated flux of Cherenkov photons. Moreover, the signal of a point run can be predicted and a simulation of the apparatus response can be carried out more reliably.

In modern stationary gas turbines for electric power generation the life time of the blades is mainly controlled by the oxidation resistance of the coatings. In the case of protective overlay coatings the surfaces are generally shot peened, whereas bond coats for EBPVD thermal barrier coatings need a smooth surface. For a better understanding of the influence of the surface roughness on the oxide scale formation, in situ studies using high temperature X-ray diffraction were performed on an MCrAlYRe coating with 12% Al and 3% Re for the use as overlay and as bond coat. The measurements were performed in air at 950 and 1000°C. The results show differences in the oxide scale formation on the same coating with an as-sprayed and a polished surface. On the as-sprayed surface Cr 2 O 3 and spinels were observed besides α-Al 2 O 3 in the initial state whereas on the polished surface a coherent α-Al 2 O 3 scale with inclusions of YAlO 3 was observed from the beginning.

The HEGRA--collaboration is operating a system of imaging atmospheric Cherenkov telescopes to search for sources of TeV-gamma-rays. Air showers are observed in stereoscopic mode with several telescopes simultaneously. To trigger the telescope system a versatile two-level trigger scheme has been implemented, which allows a significant reduction of the energy threshold with respect to single telescopes. The technical implementation of this trigger scheme and the performance of the trigger system are described. Results include the dependence of single- and multi-telescope trigger rates on the trigger thresholds, on the orientation of the telescopes, and on the type of the primary particle., 17 Pages, 10 figures, Latex

During operation, stationary blades and vanes of gas turbines are subjected to high thermal and mechanical stresses and severe oxidation. This situation can only be controlled by a composite approach in which the base material provides the necessary mechanical properties and coatings provide protection against oxidation, corrosion and, in the case of thermal barrier coatings, a part of the heat flux. For a better understanding of the oxidation processes on standalone MCrAIY overlays as well as MCr AIY used as a bond coat, in situ X-ray diffraction measurements of the formation and composition of the oxide scale at high temperatures are presented. The phase changes during oxide scale formation are discussed. Data are presented for MCrAlY coatings with 12%AI and 3%Re at three different temperatures versus time. At 950, 1000, and 1050°C a three phase oxide layer of Cr203' A1203, and NiCr2O4 was detectable. Rhenium could not be found in the oxide layer at any of the three temperatures.

In order to increase efficiency and power output of gas turbines, turbine inlet temperatures are being steadily increased. To improve the surface resistance of single crystal (SC) blades against oxidation and corrosion, the base material is coated with MCrAlY type overlay coatings. In addition to the mechanical stresses, the coating are subjected to thermal cycling which can result in fatigue cracking. Thermal cycle fatigue (TCF) properties are an important feature for selection of the system. In this paper we will present a TCF measuring method for a fast screening of uncoated and coated materials. Based on the experience with polycrystalline IN 738 LC and single crystal materials (SC 16) we will discuss TCF data. The cycles to crack initiation of coated SC is strongly influenced by grain boundaries.

An optimized method is presented for the reconstruction of air shower directions for scintillator arrays. The method takes into account that both the expectation value and the spread of the measured arrival times not only depend on the distance of a counter from the shower axis, but also on the number of particles registered in that counter. It also takes into account that the distributions of the measured arrival times are not Gaussian. For showers recorded with the HEGRA scintillator array above the threshold energy of E thres = 20 TeV the mean angular resolution obtained with this method is 〈 σ 63% θ 〉 = 1.0°, and above the threshold E thres = 50 TeV it is 〈 σ 63% θ 〉 = 0.6°. Comparing the new procedure with the HEGRA standard procedure the angular resolution has improved on average by a factor of 1.33. The mis-pointing has been determined with an accuracy of 0.15°. The method is developed using experimental data.