Compression of extreme-ultraviolet ultrashort pulses by grating configurations

The design and realization of grating instruments to condition the spectral phase of ultrashort extreme-ultraviolet pulses are discussed. The main application of such configurations is the temporal compression of pulses by compensating the phase chirp and getting close to the Fourier limit. We discuss the two configurations useful for the realization of ultrafast grating compressors, namely, the classical diffraction mount and the off-plane one. The configuration may be applied to free-electron lasers and high-order laser harmonics

Design study of time-preserving grating monochromators for ultrashort pulses in the extreme-ultraviolet and soft X-rays

The design of grating-based instruments to handle and condition coherent ultrafast pulses in the extreme-ultraviolet is discussed. The main application of such instruments is the monochromatization of high-order laser harmonics and free-electron-laser pulses in the femtosecond time scale. Broad-band monochromators require the use of diffraction gratings at grazing incidence. A grating can be used for the spectral selection of ultrashort pulses without altering the pulse duration in a significant way, provided that the number of illuminated grooves is equal to the resolution. We discuss here the design conditions to be fulfilled by a grating monochromator that does not increase the pulse duration significantly longer than the Fourier limit

Study of nanostructured targets for plasma production via laser ablation

Metal nanowires (NWs) - nanostructures 20-100 nm in diameter and up to tens of micrometers long - behave as waveguides when irradiated with light with wavelength much greater than their diameter. This is due to collective excitations of free electrons (plasmons) in the metal which couple to light and travel on the surface of the nanowire. This effect can be used to efficiently absorb laser pulses to produce dense and hot plasma on special nanostructured targets with metal nanowires vertically aligned on the surface. In this thesis work, nanostructured targets with different parameters (length, diameter, metal and fabrication process) have been irradiated with infrared laser light. X-ray flux emitted by the cooling plasma is measured during irradiation, and the depth of craters formed on the target is measured later. This data is used to choose which target parameters are best for plasma production. Different targets are compared with each other and against a control, non-nanostructured (bulk) target. As will be shown, highly significant (> 5 sigma) differences are found between targets with different nanostructures, and between nanostructured and bulk target. This differences are very difficult to explain whithout accounting for the nanostructures in the targets. Therefore, data collected and analized in this thesis work supports the hypotesys that nanostructured targets perform better than bulk targets for laser plasma production purposes, and provides useful indications for optimization of NWS' parameters

Food, Acid Supplementation and Drug Absorption - a Complicated Gastric Mix: a Randomized Control Trial.

PURPOSE:The purpose of this study was to determine the impact of food on gastric pH and the ability of over the counter betaine hydrochloride (BHCl) acid to reacidify gastric pH after food-induced elevations in gastric pH. METHODS:This open-label cross over clinical study (NCT02758015) included 9 subjects who were randomly assigned to one of 16 possible, 4-period cross-over sequences to determine the impact and relationship of food and gastric pH with acid supplementation. Subjects were administered various doses (1500 mg, 3000 mg and 4500 mg) of betaine hydrochloride (BHCl) to determine the ability of acid supplementation to reacidify gastric pH after the elevation of gastric pH caused by the ingestion of food. RESULTS:Following the administration of food and the resulting elevation in gastric pH, time to return to baseline gastric pH levels without acid supplementation was 49.7 ± 14.0 min. Administering 4500 mg of BHCl acid in capsules was able to reacidify gastric pH levels back to baseline following the administration of food in approximately 17.3 ± 5.9 min. AUCpH of each treatment were similar and not statistically different. Mean max pH following the administration of food was 3.20 ± 0.55. CONCLUSION:The ability of food to elevate and maintain gastric pH levels in the presence of acid supplementation was made evident throughout the study. A 4500 mg dose of BHCl was required to reacidify gastric pH after the administration of food. This study details the difficulty faced by clinicians in dosing a poorly soluble, weakly basic drug to patients receiving acid reducing agents where administration with food is recommended to avoid gastric side effects. TRIAL REGISTRATION:https://clinicaltrials.gov/ct2/show/NCT02758015

The First Congressional Debate on Public Carry and What It Tells Us About Firearm Regionalism

In the aftermath of District of Columbia v. Heller, a prominent issue remains unresolved: whether, or to what extent, the Second Amendment protects an individual right to keep and bear arms outside of the home. This Article explores this unresolved issue through a newly uncovered source, the congressional debates surrounding the District of Columbia\u27s public carry law in the 1890s. These debates provide new insights into the understanding of the right to keep and bear arms in the years following the drafting and ratification of the Fourteenth Amendment. Two conclusions can be drawn from the debate. First, there was no national consensus regarding a right to public carry under the Second Amendment. This is important because the Supreme Court in Heller stated that the Second Amendment codified venerable, widely understood liberties. Second, the Senators\u27 and Congressmen\u27s varied positions on the Second Amendment and the permissible scope of public carry regulations generally fell into regional patterns. Representatives of states in the North and West supported a more limited public carry right, while those representing states in the Deep South, with some exceptions, supported a broader Second Amendment right. Because the Northern Republicans were the ideological force behind the drafting and ratification of the Fourteenth Amendment, their restrictive view of public carry should be given special weight when determining the constitutionality of contemporary public carry regulations

Judging History: How Judicial Discretion in Applying Originalist Methodology Affects the Outcome of Post-Heller Second Amendment Cases

This Article aims to assess how the federal appellate courts have applied the originalist methodology in Second Amendment cases in the decade since Heller. It reviews how courts’ varying approaches to historical analysis—specifically, how courts have addressed what historical period to look to, how prevalent a historical tradition must be, and whether to address history at a high or low level of generality—can drastically affect the outcome of cases. As Justice Scalia acknowledged in McDonald, “Historical analysis can be difficult; it sometimes requires resolving threshold questions, and making nuanced judgments about which evidence to consult and how to interpret it.” Examining how courts answer these threshold questions and make nuanced judgments about history is necessary if courts are going to make consistent and predictable decisions in Second Amendment cases. In researching this Article, the author looked at fifty of the most significant Second Amendment cases across the federal circuit courts and analyzed their treatment of several methodological points. Ultimately, this research shows that while there is a near unanimous national consensus within the federal circuit courts on the overall framework for assessing Second Amendment challenges—known as the “two-step test” or the “two-part test”—there are important unresolved methodological issues that have an important impact on how Second Amendment cases are analyzed and decided. These methodological issues, which exist within the consensus framework, allow judges to influence the ultimate decision in a case while appearing to apply objective criteria. This Article aims to bring these issues to the fore and to encourage further consideration of these important originalist methodological points