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From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions. © Copyright.

The purpose of this study was to explore the initial perceptions and experiences of faculty whose classes were moved to an online/distance delivery as a result of the COVID-19 pandemic Using mixed methods online survey methodology, the researchers sought to describe faculty perceptions relative to their response to moving all university courses online within the timeframe allotted by university leadership Building upon this groups’ previous research, which focused on the relationships among care and rigor in the online teaching/learning environment, the researchers designed survey questions to further explore these concepts during a time of chaos The survey addressed faculty perceptions and lived experiences related to supporting this transition, previous experiences with online teaching, the role of rigor and care in course design and implementation, and opportunities for demonstrating care toward colleagues Information gleaned from the study will help to inform university leadership, instructional design support personnel, and faculty As the long-term economic, social, and academic effects are realized across the world, the researchers anticipate significant changes in higher education © Copyright © 2020 Cameron-Standerford, Menard, Edge, Bergh, Shayter, Smith and VandenAvond

Man-made space debris is dominating the background meteorite environment with a growing debris population leading to increased collision risks for satellites, especially in the low Earth orbit and geostationary orbit protected environments. Here we present a computational model for estimating the effect of hypervelocity impact from debris particles on non-shielded propellant and pressurant tanks. Eulerian hydrocode simulation is utilised to model firstly penetration and shock wave formation in the propellant and secondly subsequent detonation wave propagation and interaction with the tank wall. Furthermore, reactive molecular dynamics is used to estimate the risk of detonation in a liquid hydrazine layer. We present simulations of a 3.5 mm aluminium spherical debris particle at a velocity of 14 km/s relative to a hydrazine tank. We find that the degree of damage is strongly dependent on tank temperature and hence on the satellite thermal configuration at its end of life.

The Singing-ground Survey (SGS) was designed to exploit the conspicuous breeding-season display of male American woodcock (Scolopax minor; hereafter, woodcock) to monitor these otherwise inconspicuous birds. The SGS was standardized in 1968 and has since been conducted annually to derive an index of abundance and population trend. Counts of singing male woodcock on the SGS have generally declined through time, but without knowledge of the relationship among counts, woodcock abundance, and the factors affecting detection, considerable uncertainty remains in interpretation of SGS data. Using modified SGS protocols, we surveyed SGS routes in Pine County, Minnesota, in 2009 and 2010 and developed models to assess factors associated with detection probability and estimated occupancy. The intercept-only model (i.e., constant detection and occupancy probabilities across sites and no covariates) included overall detection probability of 0.59 (SE = 0.018) in 2009 and 0.66 (SE = 0.017) in 2010 with an occupancy estimate of 0.74 (SE = 0.049) in 2009 and 0.81 (SE = 0.044) in 2010. The best-supported model of detection probability for both years combined included detection as a function of woodcock abundance, observer, date, disturbance level (i.e., ambient noise that interfered with detecting woodcock), and wind speed. High wind speeds were negatively related to detection, different observers had different detection probabilities, date was quadratically related to detection (indicating a mid-period peak in detection), and high woodcock abundance and low disturbance levels were positively related to detection. We provide suggestions for incorporating these resulting into SGS protocol and analyses.

As a group of three teacher educators representing reading, special education, and educational leadership, the authors conducted a self-study of their online teaching practices with the guiding question of “How can we use multimodal literacies to re-see our practices and to empower others to construct and to communicate meaning?” The purpose was to explore the pedagogic potentials of multimodal literacy by acting upon recent findings from their longitudinal, collaborative self-study into how they use and learn through visual literacy. They sought to extend their line of inquiry and to more inclusively empower learners to negotiate and to make meaning through multimodal literacy practices. Findings document how using protocols to critically “read,” discuss, and collaboratively make meaning from their online teaching practices illuminated the relationship of multimodal texts, visuals and literacy practices in fostering access, opportunity, and ownership for learners in online courses.

The American Woodcock (Scolopax minor; hereafter, woodcock) Singing-ground Survey (SGS) is conducted annually during the woodcock breeding season, and survey points along survey routes are set 0.4 mile (0.65 km) apart to avoid counting individual birds from >1 listening location. The effective area surveyed (EAS) at a listening point is not known, and may vary as a function of land-cover type or other factors. To define the relationship describing distance between vocalizing woodcock and an observer and how cover types influence that relationship, we broadcast a recording of woodcock vocalizations in 2 land-cover types (forest and field) at varying distance. We evaluated the proportion of call broadcasts detected as a function of distance and fit regression curves to detection data to estimate a distance (r*) where the area above the curve at distances r*, which allowed determination of the radius of an area where detection probability was effectively 1.0. This EAS had a radius (r*) of 198 m for forest, 384 m for field, and 309 m for both of these land-cover types combined, and an estimated size of 12.3 ha for forest, 46.3 ha for field, and 30.0 ha for both land-cover types combined. We used this information to estimate density of displaying male woodcock based on counts from the SGS in east-central Minnesota that incorporated variation in EAS, probability of detection, survey date, and survey route. Our density estimates (5.0 birds/100 ha in 2009 and 7.1 birds/100 ha in 2010) represent the highest density of singing male American woodcock yet reported, and indicated a substantive increase in density between years.

The magnetically frustrated spin ice family of materials is host to numerous exotic phenomena such as magnetic monopole excitations and macroscopic residual entropy extending to low temperature. A finite-temperature ordering transition in the absence of applied fields has not been experimentally observed in the classical spin ice materials Dy2Ti2O7 and Ho2Ti2O7. Such a transition could be induced by the application of pressure, and in this work we consider the effects of uniaxial pressure on classical spin ice systems. Theoretically we find that the pressure induced ordering transition in Dy2Ti2O7 is strongly affected by the dipolar interaction. We also report measurements on the neutron structure factor of Ho2Ti2O7 under pressure, and compare the experimental results to the predictions of our theoretical model., Comment: 8 pages, 9 figures

Patients wanting to discontinue their antidepressant use may experience antidepressant discontinuation syndrome (ADS). This is characterized by symptoms such as nausea, vomiting, diarrhea, headaches and sweating. Withdrawal symptoms can discourage patients from permanently discontinuing antidepressants. We present the case of a 48-year-old visually impaired woman where, after a first attempt failed, venlafaxine was successfully discontinued after a switch to fluoxetine. Fluoxetine mediated discontinuation is a simple, effective and inexpensive method for patients who suffer from withdrawal symptoms when tapering off antidepressants.

We are three teacher educators – Christi, Bethney, and Abby – representing literacy, educational leadership, and special education, who have collaborated in self-studies of our teacher education practices (S-STEP) over a period of five academic years. Through this collaborative engagement, we came to recognize the similarities and differences in our language and values found within each of our individual disciplinary cultures. It was through the juxtaposition of studying ourselves alongside of that of our colleagues that we further generated a shared culture and common understandings. In our chapter, we explore the ways in which self-study enabled collaboration with teacher educators representing different disciplines. The research brought to light specific disciplinary values, assumptions, and terminology that, when articulated and examined among critical friends, facilitated our ability to both broaden and deepen our individual understandings of teacher education practices in light of each other’s diverse disciplinary perspectives.

Polycystic ovary syndrome (PCOS) is a polygenic disorder with a variable phenotype that commonly affects women of reproductive age. It can significantly affect a woman's ability to conceive and her quality of life. Effective treatment includes a multidisciplinary team approach that addresses the physiological and psychosocial manifestations of the disorder. Nurses have an important role in promoting early detection, education, and identification of services and resources to improve a woman's fertility and lifelong health.

The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

Background: Fifth-year medical students from the University of Pretoria participated in a four-week rotation in the primary care clinics of a large metropolitan centre. An academic service-learning (ASL) approach was introduced into this rotation to improve the integration of theoretical learning and clinical practice through relevant community service and structured reflection. Methods: Students wrote semi-structured reflective journals as a means to gaining greater insight into their learning experiences. These reflections were analysed qualitatively with a view to improving the community-based curriculum. Results: Four major themes were identified: expectations and the reality of primary care; service and learning; becoming a doctor; and making a difference. Conclusion: While students gained a deeper insight into their development as clinicians, using an ASL approach also assisted the faculty in making an informed educational diagnosis of the curriculum.Keywords: service learning, reflection, primary care, educational diagnosis

Extremely intense and ultrafast X-ray pulses from free-electron lasers offer unique opportunities to study fundamental aspects of complex transient phenomena in materials. Ultrafast time-resolved methods usually require highly synchronized pulses to initiate a transition and then probe it after a precisely defined time delay. In the X-ray regime, these methods are challenging because they require complex optical systems and diagnostics. Here we propose and apply a simple holographic measurement scheme, inspired by Newton's 'dusty mirror' experiment, to monitor the X-ray-induced explosion of microscopic objects. The sample is placed near an X-ray mirror; after the pulse traverses the sample, triggering the reaction, it is reflected back onto the sample by the mirror to probe this reaction. The delay is encoded in the resulting diffraction pattern to an accuracy of one femtosecond, and the structural change is holographically recorded with high resolution. We apply the technique to monitor the dynamics of polystyrene spheres in intense free-electron-laser pulses, and observe an explosion occurring well after the initial pulse. Our results support the notion that X-ray flash imaging can be used to achieve high resolution, beyond radiation damage limits for biological samples. With upcoming ultrafast X-ray sources we will be able to explore the three-dimensional dynamics of materials at the timescale of atomic motion.

Cuban Parrots (Amazona leucocephala) on the island of Great Abaco in the Bahamas forage and nest in native pine forests. The population is unique in that the birds nest in limestone solution holes on the forest floor. Bahamian pine forests are fire-dependent with a frequent surface fire regime. The effects of fire on the parrots, especially while nesting, are not well known. We measured ambient conditions inside a cavity characteristic of the Cuban Parrot's Abaconian population as a prescribed fire passed over it. Cavity conditions were relatively benign; although temperatures immediately outside the cavity rose to >800° C, inside temperatures increased only 5° C at 30 cm inside the entrance and 0.4° C at the cavity floor (cavity depth was ∼120 cm). CO2 levels briefly rose to 2,092 ppm as the flames passed, but dropped to nearly ambient levels approximately 15 min later. Smoke levels also were elevated only briefly, with 0.603 mg of total suspended particulates filtered from 0.1 m3 of air. Smokey...

In x Ga 1 − x As ( x ⩾ 0.57) thin layers were grown on GaAs by molecular beam epitaxy using an InAlAs graded buffer. Surface roughness of the graded buffer decreased with reduced buffer thickness and growth temperature. The InGaAs layers grown on a graded buffer revealed a larger tilting angle, a higher residual strain and electron mobility than those grown directly on GaAs. Increasing the graded buffer thickness above 1.2 μm did not improve the transport properties of InAs. The InAs mobility increased with layer thickness. This was explained by assuming two conducting channels, given μ 300 = 1.8 × 10 4 cm 2 /(V s) and μ 77 = 5.1 × 10 4 cm 2 /(V s) for bulk InAs.

Metamorphic InxGa1−xAs/InAlAs (x ≥ 0.8) modulation doped heterostructures have been grown on GaAs using a linearly graded In(AlGa)As buffer layer, and their structural and electric properties have been investigated. Surface morphology was found to depend on growth temperature and graded buffer thickness. Low growth temperature resulted in a relatively smooth surface with a minimum root-mean-square roughness value of 4–7 nm. The In(AlGa)As graded buffer effectively prevented dislocations from threading into the top layers. The epilayer grown on the graded buffer was tilted and not fully relaxed. High electron mobility and sheet density were achieved. The highest mobility value was 13740 cm2/Vs with a carrier density of 1.9 1012 cm−2 at 300 K. These values are comparable with InP-based InGaAs/InAlAs modulation doped heterostructures.

Damage to VUV, EUV, and X-ray Optics IV; and EUV and X-ray Optics: Synergy between Laboratory and Space III SPIE Optics + Optoelectronics: Advances in X-ray Free-Electron Laser Instrumentation, Prague, Czech Republic, 15 Apr 2013 - 18 Apr 2013; Proceedings of SPIE 8777, (2013). doi:10.1117/12.2019299, Published by SPIE, Bellingham, Wash.

A detailed chemical analysis and quantification of oxygen-containing monoterpenes in auto-oxidizedd-limonene was performed. Some of these, e.g. the cis- and trans-isomers of limonene-2-hydroperoxide, have previously been shown to exhibit strong contact allergenic properties. GC-MS with chemical ionization in negative ion mode was shown to be a successful method for the identification and determination of the molecular weight of chemically unstable limonene hydroperoxides. An HPLC method for isolation of individual compounds in auto-oxidizedd-limonene is presented. Two different stationary phases were used in normal phase mode, cyanopropyl- and diamino-modified silica. The method described can be used for the isolation of individual contact allergens in sensitization experiment vehicles, such as petrolatum and olive oil. This makes it possible to study whether test compounds, such as hydroperoxides, are chemically stable during a sensitization experiment.

Activation of either the adenylate cyclase pathway with forskolin or the guanylate cyclase pathway with sodium nitroprusside fails to induce active relaxation of serotonin-precontracted human umbilical artery smooth muscle (HUASM) but causes active relaxation of serotonin-precontracted bovine carotid artery smooth muscle (BCASM). This difference in response appears to be unique to HUASM in that all other vascular muscles exhibit relaxation in response to these substances. Forskolin and sodium nitroprusside stimulation leads to respective increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) concentrations in HUASM and BCASM. cAMP- and cGMP-dependent protein kinases are both present in HUASM and can be activated in homogenates of HUASM by the addition of exogenous cAMP and cGMP, respectively. When either forskolin or nitroprusside acts in BCASM, two low-molecular-weight proteins display an increase in the extent of phosphorylation. Neither protein shows such an increase when HUASM is treated with either agent. Thus the inability of HUASM to display active relaxation appears to be secondary to impaired activation of cyclic nucleotide-dependent protein kinases. The refractoriness to active relaxation may contribute to the vasospasm that occurs in the umbilical vasculature with parturition.

X-ray lasers offer new possibilities for creating and probing extreme states of matter. We used intense and short x-ray pulses from the FLASH soft x-ray laser to trigger the explosions of CH${}_{4}$ and CD${}_{4}$ molecules and their clusters. The results show that the explosion dynamics depends on cluster size and indicate a transition from Coulomb explosion to hydrodynamic expansion in larger clusters. The explosion of CH${}_{4}$ and CD${}_{4}$ clusters shows a strong isotope effect: The heavier deuterons acquire higher kinetic energies than the lighter protons. This may be due to an extended inertial confinement of deuterons vs. protons near a rapidly charging cluster core during exposure.

Pulse intensities greater than 10(17) Watt/cm(2) were reached at the FLASH soft X-ray laser in Hamburg, Germany, using an off-axis parabolic mirror to focus 15 fs pulses of 5-70 mu J energy at 13.5 nm wavelength to a micron-sized spot. We describe the interaction of such pulses with niobium and vanadium targets and their deuterides. The beam produced craters in the solid targets, and we measured the kinetic energy of ions ejected from these craters. Ions with several keV kinetic energy were observed from craters approaching 5 mu m in depth when the sample was at best focus. We also observed the onset of saturation in both ion acceleration and ablation with pulse intensities exceeding 10(16) W/cm(2), when the highest detected ion energies and the crater depths tend to saturate with increasing intensity. A general difficulty in working with micron and sub-micron focusing optics is finding the exact focus of the beam inside a vacuum chamber. Here we propose a direct method to measure the focal position to a resolution better than the Rayleigh length. The method is based on the correlation between the energies of ejected ions and the physical dimensions of the craters. We find that the focus position can be quickly determined from the ion time-of-flight (TOF) data as the target is scanned through the expected focal region. The method does not require external access to the sample or venting the vacuum chamber. Profile fitting employed to analyze the TOF data can extend resolution beyond the actual scanning step size. (C) 2011 Elsevier B.V. All rights reserved.

Powerful free electron lasers (FELs) operating in the soft X-ray regime are offering new possibilities for creating and probing materials under extreme conditions. We describe here simulations to model the interaction of a focused FEL pulse with metallic solids (niobium, vanadium, and their deuterides) at 13.5 nm wavelength (92 eV) with peak intensities between 1015 to 1018 W/cm2 and a fixed pulse length of 15 femtoseconds (full width at half maximum). The interaction of the pulse with the metallic solids was modeled with a non-local thermodynamic equilibrium code that included radiation transfer. The calculations also made use of a self-similar isothermal fluid model for plasma expansion into vacuum. We find that the time-evolution of the simulated critical charge density in the sample results in a critical depth that approaches the observed crater depths in an earlier experiment performed at the FLASH free electron laser in Hamburg. The results show saturation in the ablation process at intensities exceeding 1016 W/cm2. Furthermore, protons and deuterons with kinetic energies of several keV have been measured, and these concur with predictions from the plasma expansion model. The results indicate that the temperature of the plasma reached almost 5 million K after the pulse has passed.

This study determined the perceptions of obstetric physiotherapists on the state of breast-feeding in South Africa and their contribution to breast-feeding education. A questionnaire to the 134 members of the Obstetric Association of the South African Society of Physiotherapy was completed by 36 practising respondents and 23 non-practitioners. The total response rate was 44%. A significantly larger group of practising respondents who had completed their training in the seventies returned the questionnaire. About 93% of respondents felt their basic training in breast-feeding had been inadequate. Almost 56% has received further training in breast-feeding during the previous five years. Regarding the impact of the South African national breast-feeding week campaign, 47% of respondents perceived a change in attitudes toward breastfeeding and 22% a change in breast-feeding practices. It is concluded that the perceptions of other groups of health professionals, the educational needs of parents and effective educational strategies also need investigation.

Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 10(17) W/cm(2) were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 10(16) W/cm(2). This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.

A linear accelerator based source of coherent radiation, FLASH (Free-electron LASer in Hamburg) provides ultra-intense femtosecond radiation pulses at wavelengths from the extreme ultraviolet (XUV; lambda< 100nm) to the soft X-ray (SXR; lambda

Detailed structural investigations on living cells are problematic because existing structural methods cannot reach high resolutions on non-reproducible objects. Illumination with an ultrashort and extremely bright X-ray pulse can outrun key damage processes over a very short period. This can be exploited to extend the diffraction signal to the highest possible resolution in flash diffraction experiments. Here we present an analysis of the interaction of a very intense and very short X-ray pulse with a living cell, using a non-equilibrium population kinetics plasma code with radiation transfer. Each element in the evolving plasma is modeled by numerous states to monitor changes in the atomic populations as a function of pulse length, wavelength, and fluence. The model treats photoionization, impact ionization, Auger decay, recombination, and inverse bremsstrahlung by solving rate equations in a self-consistent manner and describes hydrodynamic expansion through the ion sound speed. The results show that subnanometer resolutions could be reached on micron-sized cells in a diffraction-limited geometry at wavelengths between 0·75 and 1·5 nm and at fluences of 1011–1012 photons μm−2in less than 10 fs. Subnanometer resolutions could also be achieved with harder X-rays at higher fluences. We discuss experimental and computational strategies to obtain depth information about the object in flash diffraction experiments.

The interaction of 32.5 and 6 nm ultrashort X-ray pulses with the solid materials B4C, SiC and Si is simulated with a non-local thermodynamic equilibrium (NLTE) radiation transfer code. We study the ionization dynamics as function of depth in the material, modifications of the opacity during irradiation and estimate crater depth. Furthermore, we compare the estimated crater depth with experimental data, for fluences up to 2.2 J/cm2. Our results show that at 32.5 nm irradiation, the opacity changes with less than a factor of 2 for B4C and Si and a factor of 3 for SiC, for fluences up to 200 J/cm2. At a laser wavelength of 6 nm, the model predicts a dramatic decrease in opacity due to the weak inverse bremsstrahlung, increasing the crater depth for high fluences., 9 pages, 9 color figures

Short-pulse ultraviolet and x-ray free electron lasers of unprecedented peak brightness are in the process of revolutionizing physics, chemistry, and biology. Optical components for these new light sources have to be able to withstand exposure to the extremely high-fluence photon pulses. Whereas most optics have been designed to stay intact for many pulses, it has also been suggested that single-pulse optics that function during the pulse but disintegrate on a longer timescale, may be useful at higher fluences than multiple-pulse optics. In this paper we will review damage-resistant single-pulse optics that recently have been demonstrated at the FLASH soft-x-ray laser facility at DESY, including mirrors, apertures, and nanolenses. It was found that these objects stay intact for the duration of the 25-fs FLASH pulse, even when exposed to fluences that exceed the melt damage threshold by fifty times or more. We present a computational model for the FLASH laser-material interaction to analyze the extent to which the optics still function during the pulse. Comparison to experimental results obtained at FLASH shows good quantitative agreement.

At the recently built FLASH x-ray free-electron laser, we studied the reflectivity of Si/C multilayers with fluxes up to 3 x 10(14) W/cm2. Even though the nanostructures were ultimately completely destroyed, we found that they maintained their integrity and reflectance characteristics during the 25-fs-long pulse, with no evidence for any structural changes over lengths greater than 3 A. This experiment demonstrates that with intense ultrafast pulses, structural damage does not occur during the pulse, giving credence to the concept of diffraction imaging of single macromolecules.

The first soft X-ray free-electron laser has recently been put into operation at DESY in Hamburg. Tunable soft X-ray coherent radiation can be generated at the FLASH (Free-electron LASer in Hamburg; formerly known as VUV FEL or TTF2 FEL). In the interaction experiments reported here, the laser system provided ~ 25-fs, ~ 10-μ J pulses of 32-nm radiation. We irradiated thin (500 nm) layers of poly (methyl methacrylate) – PMMA deposited on a silicon substrate by single, focused FLASH pulses. The pulse energy was adjusted using a gas attenuator.

X-ray free-electron lasers (XFELs) are currently under development and will provide a peak brightness more than 10 orders of magnitude higher than modern synchrotrons. The goal of this project was to perform the fundamental research to evaluate the possibility of harnessing these unique x-ray sources to image single biological particles and molecules at atomic resolution. Using a combination of computational modeling and experimental verification where possible, they showed that it should indeed be possible to record coherent scattering patterns from single molecules with pulses that are shorter than the timescales for the degradation of the structure due to the interaction with those pulses. They used these models to determine the effectiveness of strategies to allow imaging using longer XFEL pulses and to design validation experiments to be carried out at interim ultrafast sources. They also developed and demonstrated methods to recover three-dimensional (3D) images from coherent diffraction patterns, similar to those expected from XFELs. The images of micron-sized test objects are the highest-resolution 3D images of any noncrystalline material ever formed with x-rays. The project resulted in 14 publications in peer-reviewed journals and four records of invention.

Theory predicts that with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus, or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft X-ray free-electron laser. An intense 25 fs, 4 10^13 W/cm^2 pulse, containing 10^12 photons at 32 nm wavelength, produced a coherent diffraction pattern from a nano-structured non-periodic object, before destroying it at 60,000 K. A novel X-ray camera assured single photon detection sensitivity by filtering out parasitic scattering and plasma radiation. The reconstructed image, obtained directly from the coherent pattern by phase retrieval through oversampling, shows no measurable damage, and extends to diffraction-limited resolution. A three-dimensional data set may be assembled from such images when copies of a reproducible sample are exposed to the beam one by one., revtex, 6 pages, 4 figures

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.

Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

Background Women with breast cancer are at high risk of bilateral breast cancer. We aimed to assess the incidence of bilateral breast cancer in relation to age and time since diagnosis of first cancer. Methods We analysed a population-based cohort of 123757 women with a first primary breast cancer diagnosed in Sweden from 1970 to 2000 for frequency of bilateral breast cancers and deaths by means of record linkage. Second primary breast cancers were categorised as synchronous bilateral breast cancers if diagnosed within 3 months of the first primary cancer or as metachronous if diagnosed more than 3 months after diagnosis of first primary cancer. Findings We identified 6550 women who had developed bilateral breast cancer. Age-incidence patterns of synchronous and unilateral breast cancer were similar, although the absolute rates of synchronous bilateral cancer were 50-100 times lower than those of unilateral cancer. A woman aged 80 years or older is at least twice as likely to be diagnosed with synchronous bilateral breast cancer than is a woman younger than 40 years. In the first 20 years after diagnosis of primary breast cancer, incidence of metachronous bilateral cancer decreased from about 800 per 10(5) person-years to 400 per 10(5) person-years in patients diagnosed with primary breast cancer before the age of 45 years, whereas incidence remained at 500-600 per 10(5) person-years in those age 45 years or older at diagnosis. After 30 years’ follow-up, cumulative risk of metachronous bilateral breast cancer was about 15% irrespective of age at first primary breast cancer. Interpretation The higher than expected risk of synchronous bilateral breast cancer could be explained by non-genetic factors. By contrast, incidence of metachronous bilateral cancer fits neither a model of highly penetrant genes nor aggregation of environmental risk factors.

The Sub‐Picosecond Photon Source (SPPS), in operation since May 2003, makes x‐ray pulses of 100 fs. Spontaneous radiation originates from a short pulsed electron beam that passes through an undulator at the Stanford Linear Accelerator Center. New techniques characterize the x‐rays, the electrons, and the timing jitter in real time. These results provide a framework for discussion of possible strong field experiments at SPPS and at future fourth‐generation photon sources like the recently funded Linac Coherent Light Source.

A microscopic sample placed into a focused x-ray free electron laser beam will explode due to strong ionization on a femtosecond time scale. The dynamics of this Coulomb explosion has been modeled by Neutze et al. [Nature (London) 406, 752 (2000)] for a protein, using computer simulations. The results suggest that by using ultrashort exposures, structural information may be collected before the sample is destroyed due to radiation damage. In this paper a method is presented to include the effect of screening by free electrons in the sample in a molecular dynamics simulation. The electrons are approximated by a classical gas, and the electron distribution is calculated iteratively from the Poisson-Boltzmann equation. Test simulations of water clusters reveal the details of the explosion dynamics, as well as the evolution of the free electron gas during the beam exposure. We find that inclusion of the electron gas in the model slows down the Coulomb explosion. The hydrogen atoms leave the sample faster than the oxygen atoms, leading to a double layer of positive ions. A considerable electron density is located between these two layers. The fact that the hydrogens are found to explode much faster than the oxygens means that the diffracting part of the sample stays intact somewhat longer than the sample as a whole.

This book was first published in 2004. Wetlands are very sensitive and valuable ecosystems that are subject to much stress from human activities. The study presented here has developed an innovative triple layer framework for analysis of wetland management. This approach provides support for spatial matching between physical planning, hydrological and ecological processes, and economic activities. The authors describe how integrated modelling at the regional scale can be achieved in practice. Following an introduction to wetlands, theoretical aspects of the contributing disciplines are discussed, as well as various aspects of integrated and spatial modelling. An applied integrated assessment of spatial wetland management for the Vecht area between Amsterdam and Utrecht is then presented. This assessment has resulted in a set of linked hydrological, ecological and economic models, formulated at the level of grids and polders, and various types of evaluations and rankings of scenarios. The results indicate the value of maintaining spatial detail for as long as possible.