1,419 research outputs found
Nano-modulated electron beams via electron diffraction and emittance exchange for coherent x-ray generation
We present a new method for generation of relativistic electron beams with
current modulation on the nanometer scale and below. The current modulation is
produced by diffracting relativistic electrons in single crystal Si,
accelerating the diffracted beam and imaging the crystal structure, then
transferring the image into the temporal dimension via emittance exchange. The
modulation period can be tuned by adjusting electron optics after diffraction.
This tunable longitudinal modulation can have a period as short as a few
angstroms, enabling production of coherent hard x-rays from a source based on
inverse Compton scattering with total accelerator length of approximately ten
meters. Electron beam simulations from cathode emission through diffraction,
acceleration and image formation with variable magnification are presented
along with estimates of the coherent x-ray output properties
Inverse probability weighting to estimate causal effect of a singular phase in a multiphase randomized clinical trial for multiple myeloma.
Comparison between multiparameter radar rainfall estimates and raingauge measurements during convective storms over Po valley
In this paper radar rainfall estimates obtained from C-band Doppler polarimetric weather radar GPM 500C are compared with rain gauge measurements collected by three rain gauge networks during a two months period from September 1 to October 30, 1996 when many convective thunderstorms developed over the Po valley area. In order to verify the capability and the accuracy of radar rainfall estimates two different techniques of comparison with the rain gauges have been analyzed: the first one is based on pointwise comparison of conventional and/or multiparameter radar estimates with the rain gauges measurements, the second
utilizes the matching of the cumulative distribution function observed by the two sensors. The results are discussed considering two different areas, where the rain
gauges are at a distance less than 40 km and at a distance ranging between 40 and 80 km, respectively
Measures taken to reduce the risk of West Nile virus transmission by transplantation in Italy.
Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz
A design for a compact x-ray light source (CXLS) with flux and brilliance
orders of magnitude beyond existing laboratory scale sources is presented. The
source is based on inverse Compton scattering of a high brightness electron
bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency
standing-wave linac and RF photoinjector powered by a single ultrastable RF
transmitter at x-band RF frequency. The high efficiency permits operation at
repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating
with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The entire
accelerator is approximately 1 meter long and produces hard x-rays tunable over
a wide range of photon energies. The colliding laser is a Yb:YAG solid-state
amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as
the accelerator. The laser pulse is frequency-doubled and stored for many
passes in a ringdown cavity to match the linac pulse structure. At a photon
energy of 12.4 keV, the predicted x-ray flux is
photons/second in a 5% bandwidth and the brilliance is in pulses with RMS pulse
length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic
energy, 10 microamp average current, 0.5 microsecond macropulse length,
resulting in average electron beam power of 180 W. Optimization of the x-ray
output is presented along with design of the accelerator, laser, and x-ray
optic components that are specific to the particular characteristics of the
Compton scattered x-ray pulses.Comment: 25 pages, 24 figures, 54 reference
XCC: An X-ray FEL-based Compton Collider Higgs Factory
This report describes the conceptual design of a Higgs factory
in which 62.8 GeV electron beams collide with 1 keV X-ray free electron laser
(XFEL) beams to produce colliding beams of 62.5 GeV photons. The Higgs boson
production rate is 80,000 Higgs bosons per 10 second year, roughly the same
as the ILC Higgs rate at =250 GeV. The electron accelerator is based
on cold copper distributed coupling (C) accelerator technology. Unlike the
center-of-mass energy spectra of previous optical wavelength
collider designs, the sharply peaked center-of-mass energy
spectrum of XCC produces model independent Higgs coupling measurements with
precision on par with colliders. For the triple Higgs coupling
measurement, the XCC center-of-mass energy can be upgraded to 380 GeV, where
the cross section for is twice that of at =500 GeV. Design challenges are discussed, along
with the R\&D to address them, including demonstrators.Comment: 30 pages, 21 figures, submitted to JINST. arXiv admin note:
substantial text overlap with arXiv:2203.0848
Effects of the abrupt switch from solution tomodified-release granule formulation of valproate
Background - A new modified-release (MR) granule formulation of valproate (VPA) has been recently developed for the treatment of children with epilepsy. It consists of tasteless microspheres that can be sprinkled on soft foods and easily swallowed. There are no data on the effectiveness of this formulation in pediatric age. Aim of the study -To evaluate the effects of the abrupt switch from solution to VPA MR granules in children undergoing chronic treatment. Methods -We enrolled children receiving VPA solution as sole or adjunctive therapy and switched them to MR granules at identical dosages. VPA blood level, treatment efficacy (clinical and EEG data), tolerability (adverse reactions), palatability, ease of administration, and compliance were evaluated before switching (T0) and after 4 weeks (T1). Results -Out of 112 enrolled children, 108 (96.4%) completed the evaluation. We observed no significant differences between the patients at T0 and T1 in VPA blood levels, treatment efficacy, tolerability, and compliance. MR granules were judged more palatable (P < 0.05) and easier to administer (P < 0.05) than solution by children and parents. At 6-month follow-up, all patients continued to use MR granules. Conclusion -Modified-release granule formulation of VPA may be a reliable alternative to solution for its convenience of use
Hormone replacement treatment and breast cancer risk: a cooperative Italian study.
The relationship between hormone replacement treatment (HRT) and breast cancer risk was analysed using data from a case-control study conducted between June 1991 and February 1994 in six Italian centres on 2569 patients aged below 75 with histologically confirmed breast cancer and 2588 controls admitted to hospital for a wide spectrum of acute, non-neoplastic, non hormone-related diseases. Ever HRT use was reported by 7.5% of cases and 7.5% of controls, corresponding to a multivariate odds ratio (OR) of 1.2 [95% confidence interval (CI), 0.9-1.5]. The risk increased with increasing duration of use: the ORs were 1.0 for use lasting less than 1 year, 1.3 for 1-4 years and 1.5 for 5 years or more. There was no clear pattern of risk with reference to time since starting use, but the OR was significantly elevated (OR = 2.0, 95% CI 1.3-2.9) for women who had stopped HRT within the last 10 years. No association was observed in those who had stopped HRT more than 10 years ago (OR = 1.0). The increased OR for women who had stopped HRT within the last 10 years was consistent across strata of identified covariates, and was significantly related to duration of use. This study confirms the absence of a strong association between HRT and breast cancer risk, although the risk estimate was above unity for women who had used HRT for 5 years or longer. However, the risk was significantly elevated in the short to medium term after use, particularly for long-term use. This short-term increased risk is consistent with an effect of HRT on one of the later stages of the process of breast carcinogenesis. The flattening of risk with increasing time since stopping, and hence the absence of a long-term cumulative excess in breast cancer risk after stopping HRT exposure, has relevant implications on individual risk assessment and public health
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