A Study of Direct Photon Production in Hadronic Interactions

This thesis presents results on direct photon production in pi--p and pi+-p interactions at an incident beam momentum of 280 GeV/c, using data recorded by CERN experiment WA70 at the Omega Prime Spectrometer. The direct photon cross-section, and the ratio of direct photon and pi cross-sections, is measured over the Pt range 4-7 GeV/c and the Feynman X range -0.4 to 0.4. Chapter 1 gives an account of the theoretical framework used to describe direct photon production, together with a brief review of recent experimental results. Chapter 2 describes the experimental apparatus used by WA70, with particular emphasis on the high-granularity electromagnetic calorimeter constructed specifically for the experiment. Chapter 3 discusses the reconstruction programs used to process the raw data from the Omega Prime Spectrometer and calorimeter prior to performing any physics analysis. Chapter 4 describes the sequence of cuts used to isolate the pi0 and direct photon signals in the experimental data. In Chapter 5, the efficiencies of detection of pi0s and direct photons, and the residual backgrounds in the direct photon signal, are determined. The simulation programs used to measure these efficiencies and backgrounds are described, together with the methods used when the simulation programs could not be applied. Finally, in Chapter 6 the cross-sections for direct photon and pi0 production and the ratio of the cross-sections are presented. The pi0 cross-sections are compared to the parametrised results from other experiments, and the direct photon cross-sections are compared with the predictions of next-to-leading order perturbative quantum chromodynamics

Beyond the Hoax: A Response to Emily A. Schultz

I am grateful to the editors of Reviews in Anthropology for giving me the opportunity to respond to Emily Schultz’s review (2010) of my book Beyond the Hoax: Science, Philosophy and Culture (2008). I shall begin by briefly correcting several of Schultz’s misrepresentations of my ideas. I shall then endeavor to address the intellectually interesting issues that she raises

Time to Treat: A System Redesign Focusing on Decreasing the Time from Suspicion of Lung Cancer to Diagnosis

IntroductionMultiple investigations often result in a lengthy process from the onset of lung cancer–related symptoms until diagnosis. An unpublished chart audit indicated suboptimal delays in patients' courses from onset of symptoms until diagnosis of cancer.MethodsThe Time to Treat Program was designed for patients with clinical or radiographic suspicion of lung cancer. Pre- and postimplementation data on median wait times were compared.ResultsFrom April 2005 to January 2007, 430 patients were referred. After Time to Treat Program implementation, the median time from suspicion of lung cancer to referral for specialist consultation decreased from 20 days to 6 days, and the median time from such referral to the actual consultation date decreased from 17 days to 4 days. The median time from specialist consultation to computed tomography scan decreased from 52 days to 3 days, and the median time from computed tomography scan to diagnosis decreased from 39 days to 6 days. Overall, the median time from suspicion of lung cancer to diagnosis decreased from 128 days to 20 days. Of all patients in the Time to Treat Program, 33% were eventually diagnosed with lung cancer.ConclusionsTime to Treat Program was effective in shortening the time from suspicion of lung cancer to diagnosis and reduced time intervals at each step in the process. Earlier diagnosis of lung cancer may allow increased treatment options for patients and may improve outcomes

Autonomous Medical Needle Steering In Vivo

The use of needles to access sites within organs is fundamental to many interventional medical procedures both for diagnosis and treatment. Safe and accurate navigation of a needle through living tissue to an intra-tissue target is currently often challenging or infeasible due to the presence of anatomical obstacles in the tissue, high levels of uncertainty, and natural tissue motion (e.g., due to breathing). Medical robots capable of automating needle-based procedures in vivo have the potential to overcome these challenges and enable an enhanced level of patient care and safety. In this paper, we show the first medical robot that autonomously navigates a needle inside living tissue around anatomical obstacles to an intra-tissue target. Our system leverages an aiming device and a laser-patterned highly flexible steerable needle, a type of needle capable of maneuvering along curvilinear trajectories to avoid obstacles. The autonomous robot accounts for anatomical obstacles and uncertainty in living tissue/needle interaction with replanning and control and accounts for respiratory motion by defining safe insertion time windows during the breathing cycle. We apply the system to lung biopsy, which is critical in the diagnosis of lung cancer, the leading cause of cancer-related death in the United States. We demonstrate successful performance of our system in multiple in vivo porcine studies and also demonstrate that our approach leveraging autonomous needle steering outperforms a standard manual clinical technique for lung nodule access.Comment: 22 pages, 6 figure

Structural and Functional Characterization of MppR, an Enduracididine Biosynthetic Enzyme from Streptomyces hygroscopicus: Functional Diversity in the Acetoacetate Decarboxylase-like Superfamily

The nonproteinogenic amino acid enduracididine is a critical component of the mannopeptimycins, cyclic glycopeptide antibiotics with activity against drug-resistant pathogens, including methicillin-resistant Staphylococcus aureus. Enduracididine is produced in Streptomyces hygroscopicus by three enzymes, MppP, MppQ, and MppR. On the basis of primary sequence analysis, MppP and MppQ are pyridoxal 5'-phosphate-dependent aminotransferases; MppR shares a low, but significant, level of sequence identity with acetoacetate decarboxylase. The exact reactions catalyzed by each enzyme and the intermediates involved in the route to enduracididine are currently unknown. Herein, we present biochemical and structural characterization of MppR that demonstrates a catalytic activity for this enzyme and provides clues about its role in enduracididine biosynthesis. Bioinformatic analysis shows that MppR belongs to a previously uncharacterized family within the acetoacetate decarboxylase-like superfamily (ADCSF) and suggests that MppR-like enzymes may catalyze reactions diverging from the well-characterized, prototypical ADCSF decarboxylase activity. MppR shares a high degree of structural similarity with acetoacetate decarboxylase, though the respective quaternary structures differ markedly and structural differences in the active site explain the observed loss of decarboxylase activity. The crystal structure of MppR in the presence of a mixture of pyruvate and 4-imidazolecarboxaldehyde shows that MppR catalyzes the aldol condensation of these compounds and subsequent dehydration. Surprisingly, the structure of MppR in the presence of "4-hydroxy-2-ketoarginine" shows the correct 4R enantiomer of "2-ketoenduracididine" bound to the enzyme. These data, together with bioinformatic analysis of MppR homologues, identify a novel family within the acetoacetate decarboxylase-like superfamily with divergent active site structure and, consequently, biochemical function.Keywords: Nosocomial infections, Mannopeptimycins, Active site, Gram positive bacteria, Viomycin biosynthesis, X-ray, Protein structure, Reporter group, Glycopeptide antibiotics, Ionization constan

Long- and short-term outcomes in renal allografts with deceased donors: A large recipient and donor genome-wide association study.

Improvements in immunosuppression have modified short-term survival of deceased-donor allografts, but not their rate of long-term failure. Mismatches between donor and recipient HLA play an important role in the acute and chronic allogeneic immune response against the graft. Perfect matching at clinically relevant HLA loci does not obviate the need for immunosuppression, suggesting that additional genetic variation plays a critical role in both short- and long-term graft outcomes. By combining patient data and samples from supranational cohorts across the United Kingdom and European Union, we performed the first large-scale genome-wide association study analyzing both donor and recipient DNA in 2094 complete renal transplant-pairs with replication in 5866 complete pairs. We studied deceased-donor grafts allocated on the basis of preferential HLA matching, which provided some control for HLA genetic effects. No strong donor or recipient genetic effects contributing to long- or short-term allograft survival were found outside the HLA region. We discuss the implications for future research and clinical application

Shades of empire: police photography in German South-West Africa

This article looks at a photographic album produced by the German police in colonial Namibia just before World War I. Late 19th- and early 20th-century police photography has often been interpreted as a form of visual production that epitomized power and regimes of surveillance imposed by the state apparatuses on the poor, the criminal and the Other. On the other hand police and prison institutions became favored sites where photography could be put at the service of the emergent sciences of the human body—physiognomy, anthropometry and anthropology. While the conjuncture of institutionalized colonial state power and the production of scientific knowledge remain important for this Namibian case study, the article explores a slightly different set of questions. Echoing recent scholarship on visuality and materiality the photographic album is treated as an archival object and visual narrative that was at the same time constituted by and constitutive of material and discursive practices within early 20th-century police and prison institutions in the German colony. By shifting attention away from image content and visual codification alone toward the question of visual practice the article traces the ways in which the photo album, with its ambivalent, unstable and uncontained narrative, became historically active and meaningful. Therein the photographs were less informed by an abstract theory of anthropological and racial classification but rather entrenched with historically contingent processes of colonial state constitution, socioeconomic and racial stratification, and the institutional integration of photography as a medium and a technology into colonial policing. The photo album provides a textured sense of how fragmented and contested these processes remained throughout the German colonial period, but also how photography could offer a means of transcending the limits and frailties brought by the realities on the ground.International Bibliography of Social Science