A new scientific frontier opened in 2009 with the start of operations of the world’s first x-ray freeelectron laser (FEL), the Linac Coherent Light Source (LCLS), at SLAC National Accelerator Laboratory. LCLS provides femtosecond pulses of x rays (270 eV to 11.2 keV) with very high peak brightness to access new domains of ultrafast x-ray science. This article presents the fundamental FEL physics and outlines the LCLS source characteristics along with the experimental challenges, strategies, and instrumentation that accompany this novel type of x-ray source. The main part of the article reviews the scientific achievements since the inception of LCLS in the five primary areas it serves: atomic, molecular, and optical physics; condensed matter physics; matter in extreme conditions; chemistry and soft matter, and biology.

/pdf/linac-coherent-light-source-the-first-five-years-1pbhefkf5n.pdf

Linac Coherent Light Source: The first five years

Ultrafast laser techniques have revealed extraordinary spin dynamics in magnetic materials that equilibrium descriptions of magnetism cannot explain. Particularly important for future applications is understanding non-equilibrium spin dynamics following laser excitation on the nanoscale, yet the limited spatial resolution of optical laser techniques has impeded such nanoscale studies. Here we present ultrafast diffraction experiments with an X-ray laser that probes the nanoscale spin dynamics following optical laser excitation in the ferrimagnetic alloy GdFeCo, which exhibits macroscopic all-optical switching. Our study reveals that GdFeCo displays nanoscale chemical and magnetic inhomogeneities that affect the spin dynamics. In particular, we observe Gd spin reversal in Gd-rich nanoregions within the first picosecond driven by the non-local transfer of angular momentum from larger adjacent Fe-rich nanoregions. These results suggest that a magnetic material's microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1 ps) spin reversal than in present technologies.

/pdf/nanoscale-spin-reversal-by-non-local-angular-momentum-fdruf8lb5q.pdf

Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo

A unique multidisciplinary perspective on the risk literature is used to establish a fresh and provocative argument regarding the epistemological understanding and definition of risk. Building on economic conceptualizations that distinguish risk from uncertainty and argue that risk is an ordered application of knowledge to the unknown, the survey identifies each of the disciplines as having a particular knowledge approach with which they confront the unknown so as to order its randomness and convert it into a risk proposition. This epistemological approach suggests the concept of risk can act as a mirror, reflecting the preoccupations, strengths, and weaknesses of each discipline as they grapple with uncertainty. The conclusion suggests that the different disciplines can, and desirably should, act in concert toward a cumulative appreciation of risk that progresses our understanding of the concept. One way in which the article challenges risk experts to join disciplinary forces in a collaborative effort is to holistically appreciate and articulate the concept of political risk calculation.

https://papers.ssrn.com/sol3/Delivery.cfm/risk_625.pdf?abstractid=943112&mirid=1

A Disciplinary Perspective on the Epistemological Status of Risk

How objective are forensic experts when they are retained by one of the opposing sides in an adversarial legal proceeding? Despite long-standing concerns from within the legal system, little is known about whether experts can provide opinions unbiased by the side that retained them. In this experiment, we paid 108 forensic psychologists and psychiatrists to review the same offender case files, but deceived some to believe that they were consulting for the defense and some to believe that they were consulting for the prosecution. Participants scored each offender on two commonly used, well-researched risk-assessment instruments. Those who believed they were working for the prosecution tended to assign higher risk scores to offenders, whereas those who believed they were working for the defense tended to assign lower risk scores to the same offenders; the effect sizes (d) ranged up to 0.85. The results provide strong evidence of an allegiance effect among some forensic experts in adversarial legal proceedings.

Are Forensic Experts Biased by the Side That Retained Them

With an eye toward extending optical wave-mixing techniques to the x-ray regime, we present the first experimental demonstration of a two-color x-ray free-electron laser at the Linac Coherent Light Source. We combine the emittance-spoiler technique with a magnetic chicane in the undulator section to control the pulse duration and relative delay between two intense x-ray pulses and we use differently tuned canted pole undulators such that the two pulses have different wavelengths as well. Two schemes are shown to produce two-color soft x-ray pulses with a wavelength separation up to $\ensuremath{\sim}1.9%$ and a controllable relative delay up to 40 fs.

/pdf/experimental-demonstration-of-femtosecond-two-color-x-ray-35rvxxdiff.pdf

Experimental Demonstration of Femtosecond Two-Color X-Ray Free-Electron Lasers

The results of the current studies further document that acute alcohol administration markedly disrupts the function of the HPG in the male Our results indicate that alcohol depresses serum testosterone levels and, thereby, produces clinical symptoms associated with hypoandrogenization Moreover, our studies suggest that acute alcohol administration also affects the hypothalamic-pituitary axis by reducing serum LH levels--an effect that may represent the primary action of alcohol on the HPG

Effects of Acute Alcohol Administration on Reproductive Endocrinology in the Male Rat

This manuscript raises two questions that have been surprisingly missing from the voluminous law review literature on expert evidence since the landmark Daubert decision. First, what is the underlying rationale for the replacement of the old qualifications-only, let-it-all standard for expert testimony with Daubert/Federal Rule of Evidence 702's requirement that all expert testimony be subject to a stringent reliability test? Second, once we have identified this rationale, has the Daubert revolution succeeded on its own terms? I conclude that the implicit rationale for the reliability test is to preserve the perceived advantages of the adversarial system, while mitigating the harms to the courts' truth-seeking function by the inevitable strong biases that accompany adversarial expert testimony. These biases include the conscious biases of hired guns, the unconscious biases of other paid experts, and the selection biases that result from the fact that attorneys shop for their experts from a large pool of qualified individuals. Rule 702 thus attempts to serve a worthy goal, but it far from fully succeeds in efficiently achieving this goal. First, in the context of forensic expertise in criminal cases, Rule 702 does nothing to address the huge gaps in resources between the prosecution and most defendants that severely inhibit defendants' ability to challenge unreliable prosecution expert testimony. Second, Rule 702, applied correctly, does succeed in barring junk science causation evidence in toxic torts cases. However, it does so at the expense of excluding speculative evidence supporting causation, even when most experts in the field would conclude that the relevant evidence is a sufficient basis from which to find causation by a preponderance of the evidence. While Rule 702 is easily preferable to the prior overly permissive regime, it likely goes too far in insisting on a reliability test that makes the courtroom stricter about causation evidence than is the scientific community itself. The way around this problem is to amend Rule 702 to allow courts to admit educated guesses about causation, but only when nonpartisan experts, not subject to adversarial bias, are willing to make such guesses. Finally, Rule 702 puts severe restrictions on the testimony of experience-based testimony by connoisseurs. Such experts may only testify if their field of expertise is a legitimate one, and they have proven to the court that they truly have the expertise they claim. Rule 702 also properly prevents attorneys from shopping for outlier and hired gun connoisseurs, given that there is no objective way for a jury to determine whether an experience-based expert's views are correct or representative of other experts in the field. Therefore, in the context of connoisseur testimony, courts should either replace adversarial experts with a panel of nonpartisan experts, or only allow an adversarial expert to testify if his conclusions are consistent with those of a nonpartisan advisory panel.

https://www.courts.state.co.us/userfiles/File/Court_Probation/Supreme_Court/Committees/Water_Court_Committee/expert_witmesses_adversarial_bias_07.pdf

Expert Witnesses, Adversarial Bias, and the (Partial) Failure of the Daubert Revolution

In Only One Place of Redress David E. Bernstein offers a bold reinterpretation of American legal history: he argues that American labor and occupational laws, enacted by state and federal governments after the Civil War and into the twentieth century, benefited dominant groups in society to the detriment of those who lacked political power. Both intentionally and incidentally, claims Bernstein, these laws restricted in particular the job mobility and economic opportunity of blacks.

A pioneer in applying the insights of public choice theory to legal history, Bernstein contends that the much-maligned jurisprudence of the Lochner era—with its emphasis on freedom of contract and private market ordering—actually discouraged discrimination and assisted groups with little political clout. To support this thesis he examines the motivation behind and practical impact of laws restricting interstate labor recruitment, occupational licensing laws, railroad labor laws, minimum wage statutes, the Davis-Bacon Act, and New Deal collective bargaining. He concludes that the ultimate failure of Lochnerism—and the triumph of the regulatory state—not only strengthened racially exclusive labor unions but contributed to a massive loss of employment opportunities for African Americans, the effects of which continue to this day.

Scholars and students interested in race relations, labor law, and legal

or constitutional history will be fascinated by Bernstein’s daring—and controversial—argument.

Only One Place of Redress: African Americans, Labor Regulations, and the Courts from Reconstruction to the New Deal

In this timely reevaluation of an infamous Supreme Court decision, David E. Bernstein provides a compelling survey of the history and background of Lochner v. New York. This 1905 decision invalidated a state law limiting work hours and became the leading precedent contending that novel economic regulations were unconstitutional. Sure to be controversial, "Rehabilitating Lochner" argues that despite the decision's reputation, it was well-grounded in precedent - and that modern constitutional jurisprudence owes at least as much to the limited-government ideas of Lochner proponents as to the more expansive vision of its Progressive opponents. Tracing the influence of this decision through subsequent battles over segregation laws, sex discrimination, civil liberties, and more, "Rehabilitating Lochner" argues not only that the court acted reasonably in Lochner, but that Lochner and like-minded cases have been widely misunderstood and unfairly maligned ever since.

Rehabilitating Lochner: Defending Individual Rights against Progressive Reform

The Daubert trilogy of Supreme Court cases - Daubert, Joiner, and Kumho Tire, codified in Federal Rule of Evidence 702 - has established new rules for the admissibility of scientific evidence in federal court. The situation in state courts is far more unsettled. First, a significant number of courts have continued to adhere to the tests they used before Daubert, either the Frye general acceptance test or some other test. Even among those states that have adopted Daubert, its application has been decidedly nonuniform. Only a few states have adopted the Daubert trilogy in its entirety. Some states have adopted Daubert, but have not yet adopted Kumho Tire or Joiner. Others have adopted Daubert and Kumho Tire, but not Joiner, or have adopted only part of Joiner. Still other states view the Daubert trilogy as only instructive, or as consistent with their own traditional state tests but not binding. This article analyzes the degree to which the holdings of the Daubert trilogy have been adopted by state courts. This analysis shows that there is a rich diversity of tests within the states. Indeed, contrary to the prevailing wisdom, the Daubert trilogy is not yet the majority standard even among the states that have rejected Frye.

The Daubert Trilogy in the States

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