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Human campylobacteriosis exhibits a distinctive seasonality in temperate regions. This paper aims to identify the origins of this seasonality. Clinical isolates [typed by multi-locus sequence typing (MLST)] and epidemiological data were collected from Scotland. Young rural children were found to have an increased burden of disease in the late spring due to strains of non-chicken origin (e.g. ruminant and wild bird strains from environmental sources). In contrast the adult population had an extended summer peak associated with chicken strains. Travel abroad and UK mainland travel were associated with up to 17% and 18% of cases, respectively. International strains were associated with chicken, had a higher diversity than indigenous strains and a different spectrum of MLST types representative of these countries. Integrating empirical epidemiology and molecular subtyping can successfully elucidate the seasonal components of human campylobacteriosis. The findings will enable public health officials to focus strategies to reduce the disease burden.
This Summary for Policymakers presents key findings from the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). The SREX approaches the topic by assessing the scientific literature on issues that range from the relationship between climate change and extreme weather and climate events (‘climate extremes’) to the implications of these events for society and sustainable development. The assessment concerns the interaction of climatic, environmental, and human factors that can lead to impacts and disasters, options for managing the risks posed by impacts and disasters, and the important role that non-climatic factors play in determining impacts. Box SPM.1 defines concepts central to the SREX.
The character and severity of impacts from climate extremes depend not only on the extremes themselves but also on exposure and vulnerability. In this report, adverse impacts are considered disasters when they produce widespread damage and cause severe alterations in the normal functioning of communities or societies. Climate extremes, exposure, and vulnerability are influenced by a wide range of factors, including anthropogenic climate change, natural climate variability, and socioeconomic development (Figure SPM.1). Disaster risk management and adaptation to climate change focus on reducing exposure and vulnerability and increasing resilience to the potential adverse impacts of climate extremes, even though risks cannot fully be eliminated (Figure SPM.2). Although mitigation of climate change is not the focus of this report, adaptation and mitigation can complement each other and together can significantly reduce the risks of climate change. [SYR AR4, 5.3]
A major challenge for scanned probe microscopy is to identify structures and chemical species on a surface, which have not already been inferred from other analytical techniques. Progress is impeded by the fact that in general the structure and composition of the tip atom is not known. To illustrate some of the issues involved, we report simultaneous scanning tunneling microscopy/atomic force microscopy (STM/AFM) of the TiO2 (110) surface. The use of small amplitudes enabled the simultaneous acquisition of force gradient and barrier height images during standard STM imaging. Surprisingly, we find most STM images exhibit a corrugation contrast inverse to that usually reported in the literature. However, regardless of the contrast in STM, force gradient images always showed greater attraction over O rows. Barrier height images also show this consistency, always being greater over O rows. This supports the theoretical model of the electronic structure of the surface, but shows that the tip structure and interaction cannot be ignored in modeling STM images. We conclude that there is a fine balance between topography and local density of states (LDOS) in STM imaging of this surface; which of them dominates the STM image is determined by the tip. Simultaneous multi-parameter imaging is useful in interpreting images reliably, particularly on multi-component surfaces.
A detailed investigation into the mechanisms of the ion-assisted etching of TiSi2 using 1000 eV argon ions and chlorine gas is reported. X-ray photoelectron spectroscopy (XPS) was used to investigate surface product distributions and modulated ion beam mass spectroscopy (MIBMS) was used to investigate gas phase product distributions. Identical experiments were performed on silicon and titanium single crystal substrates. Information on chemical mechanisms during ion-assisted etching was obtained by comparing the product distributions of the three substrates. For each substrate, the di and tetrachlorides were the major gas phase products. These products were emitted with high thermal velocities following a surface residence process. TiCl and TiCl2 products were found on the titanium surface after simultaneous exposure to chlorine and argon ions, but not on the TiSi2 surface. These observations are discussed in terms of specific chemical mechanisms which are critical during ion-assisted etching.
The effects of ferromagnetic capping layers on the perpendicular magnetic anisotropy of Ni/Cu(001) have been studied. X-ray magnetic circular dichroism was used to obtain element specific magnetic information, including hysteresis loops for both in-plane and perpendicular magnetization. A 15 ML Ni/Cu(001) film maintains its perpendicular magnetic orientation after the addition of a 2.5 ML Fe capping layer. The Fe capping layer reduces the area of the Ni hysteresis loop by a factor of 2.0. A 2.0 ML capping layer of Co on 15 ML Ni/Cu(001) switches the easy axis of magnetization from perpendicular to in-plane.
Monochromatized synchrotron radiation has been employed as the excitation source for soft x-ray emission spectroscopy. In the present paper changes in the emission spectra that occur as the excitation energy is varied near the core-absorption threshold are discussed. In the case of crystalline silicon, strong variations are seen in the L2,3 emission for excitation energies up to 30 eV above threshold. These variations are shown to be dependent on the crystalline order of the material and can be interpreted in terms of restrictions on the crystal momentum that arise in an inelastic scattering description of the combined absorption and emission. On the other hand this description is less relevant to the excitation-energy dependence of ionic insulators, in which strong phonon coupling removes these restrictions on crystal momentum. In the insulators B2O3 and BN strong variations in the emission are observed at threshold, upon creation of a core exciton: the exciton affects the emission through its influence on the phonon coupling as well as on the initial and final-state screening.
Selenium disulfide has been demonstrated to be an effective passivant for GaAs (001) surfaces. This chemical treatment can be more robust and effective in reducing surface-states-based Fermi level pinning than other analogous chemical treatments. We have studied SeS2-passivated surfaces, formed by treatment of GaAs in SeS2:CS2 solution, with synchrotron radiation photoemission spectroscopy. The SeS2-treated surface consists of a chemically stratified structure of several atomic layers thickness. The As-based sulfides and selenides appear to reside on the outermost surface with the Ga-based compounds adjacent to the bulk GaAs substrate. The motion of the Fermi level within the band gap was monitored during controlled annealing conditions allowing for the specific chemical moieties responsible for the reduction in surface charge to be identified. As-based species are removed at low annealing conditions with little motion of the Fermi level. GaSe-based species, formed on the surface, are clearly shown to be associated with the unpinning of the Fermi level.
This study explores the consequences of structure on the electronic properties of magnetic multilayers. Epitaxial layers of Co and Cu are grown on Cu(100) in a new deposition system that couples sputter-deposition with MBE and contains a wide range of characterization tools, including RHEED, LEED, and Kerr effect. This system can be coupled in situ to spin-polarized, angle-resolved photoemission and to resonant, magnetic X-ray scattering, both employing synchrotron radiation. The interface structure turns out to be critical in determining the coercivity and the presence of quantum well states, which determine oscillatory magnetic coupling.
Device-grade thin-film CuInSe2 was subjected to various chemical treatments commonly used in photovoltaic device fabrication to determine the resulting microscopic surface composition/morphology and the effect on II-VI/CuInSe2 heterojunction formation. HCI (38%), Br-MeOH (<1% Br), (NH4)2S, and NH4OH/thiourea solutions were used separately to modify the surface chemistry of the CuInSe2 polycrystalline films. Scanning electron microscopy was used to evaluate the resultant surface morphology. Angle-resolved high-resolution photoemission measurements on the valence band electronic structure and Cu 2p, In 3d, Ga 2p and Se 3d core lines were used to evaluate the chemistry of the chemically treated surfaces. CdS overlayers were then deposited in steps on these chemically treated surfaces. Photoemission measurements were acquired after each growth to determine the resultant heterojunction valence-band discontinuity between the CdS and the chemically modified CuInSe2 surface.
The fabrication, characterization, and performance of wafer-bonded (WB) GaInAsSb thermophotovoltaic (TPV) devices for monolithically series-interconnected cells are reported. TPV epilayers were bonded to GaAs handle wafers with SiOx/Ti/Au. This dielectric/metal layer is multi-functional in that it is used as the adhesive to bond the epilayers; it provides electrical isolation; and it is an internal back surface reflector. Considerations were made to minimize residual stress and provide high reflectivity. Excellent structural and optical properties of WB TPV structures are observed. The external quantum efficiency of WB and unbonded TPV cells is comparable. TPV cells were monolithically series interconnected, and a 10-junction device exhibited linear voltage building with an open-circuit voltage of 1.8 V.
Energies for symmetric tilt grain boundaries in pure Al and in Al with substitutional Pb defects at coincident sites along the grain boundaries were calculated using a modified embedded atom method potential and density functional theory. The agreement between the analytic potential, the first principles calculations and experiment is reasonably good for the pure system. For the Al-Pb system both the analytic potential and first principles calculations predict that Pb segregation to the interface is energetically preferred compared to the dilute solution. The application of a disclination structural unit model to calculating grain boundary energies over the entire range of tilt angles is also explained.
Karen W. L. Yee, Department of Medical Oncology and Hematology, Princess Margaret Hospital, Toronto, ON, Canada,
Susan M. O'Brien, Hematopathology and Oncology Department, Quest Diagnostics Nichols Institute, San Juan Capistrano, CA, USA
Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults in the Western world, accounting for nearly 25% of all leukemias with an estimated annual age-adjusted incidence of 3 per 100,000 persons in the United States. The median age at diagnosis is approximately 70 years, with 81% of the patients diagnosed when aged ≥ 60 years. Under the World Health Organization (WHO) classification, CLL is a B-cell neoplasm and the entity T-cell CLL has been reclassified as T-cell prolymphocytic leukemia (PLL). Recent data from the Surveillance, Epidemiology, and End Results (SEER) cancer statistics indicate that 5-year survival of patients with CLL is 73%.
Significant changes in the understanding and management of CLL have occurred in the last two decades. With the advent of newer treatment modalities, such as purine analogs and monoclonal antibodies, substantial improvements have been made in achieving complete responses (CR), with a proportion achieving molecular remissions and durable responses. Despite the advances in the treatment of patients with CLL, the majority of patients will relapse after primary therapy.
The current diagnosis of CLL is based on minor modifications of the criteria originally proposed by the National Cancer Institute (NCI) (Table 5.1). A bone marrow evaluation is no longer required for diagnosis but is useful to determine the extent and pattern of involvement and to clarify the etiology of cytopenias.
The morphology and immunophenotype are adequate for diagnosis and to distinguish CLL from other disorders (Table 5.2).