Electron Ghost Imaging.

In this Letter we report a demonstration of electron ghost imaging. A digital micromirror device directly modulates the photocathode drive laser to control the transverse distribution of a relativistic electron beam incident on a sample. Correlating the structured illumination pattern to the total sample transmission then retrieves the target image, avoiding the need for a pixelated detector. In our example, we use a compressed sensing framework to improve the reconstruction quality and reduce the number of shots compared to raster scanning a small beam across the target. Compressed electron ghost imaging can reduce both acquisition time and sample damage in experiments for which spatially resolved detectors are unavailable (e.g., spectroscopy) or in which the experimental architecture precludes full frame direct imaging.

Imaging Molecular Motion: Femtosecond X-Ray Scattering of an Electrocyclic Chemical Reaction.

Structural rearrangements within single molecules occur on ultrafast time scales. Many aspects of molecular dynamics, such as the energy flow through excited states, have been studied using spectroscopic techniques, yet the goal to watch molecules evolve their geometrical structure in real time remains challenging. By mapping nuclear motions using femtosecond x-ray pulses, we have created real-space representations of the evolving dynamics during a well-known chemical reaction and show a series of time-sorted structural snapshots produced by ultrafast time-resolved hard x-ray scattering. A computational analysis optimally matches the series of scattering patterns produced by the x rays to a multitude of potential reaction paths. In so doing, we have made a critical step toward the goal of viewing chemical reactions on femtosecond time scales, opening a new direction in studies of ultrafast chemical reactions in the gas phase.

A machine learning photon detection algorithm for coherent x-ray ultrafast fluctuation analysis.

X-ray free electron laser experiments have brought unique capabilities and opened new directions in research, such as creating new states of matter or directly measuring atomic motion. One such area is the ability to use finely spaced sets of coherent x-ray pulses to be compared after scattering from a dynamic system at different times. This enables the study of fluctuations in many-body quantum systems at the level of the ultrafast pulse durations, but this method has been limited to a select number of examples and required complex and advanced analytical tools. By applying a new methodology to this problem, we have made qualitative advances in three separate areas that will likely also find application to new fields. As compared to the "droplet-type" models, which typically are used to estimate the photon distributions on pixelated detectors to obtain the coherent x-ray speckle patterns, our algorithm achieves an order of magnitude speedup on CPU hardware and two orders of magnitude improvement on GPU hardware. We also find that it retains accuracy in low-contrast conditions, which is the typical regime for many experiments in structural dynamics. Finally, it can predict photon distributions in high average-intensity applications, a regime which up until now has not been accessible. Our artificial intelligence-assisted algorithm will enable a wider adoption of x-ray coherence spectroscopies, by both automating previously challenging analyses and enabling new experiments that were not otherwise feasible without the developments described in this work.

Mechanism and dynamics of fatty acid photodecarboxylase.

Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.

Femtosecond mega-electron-volt electron microdiffraction.

To understand and control the basic functions of physical, chemical and biological processes from micron to nano-meter scale, an instrument capable of visualizing transient structural changes of inhomogeneous materials with atomic spatial and temporal resolutions, is required. One such technique is femtosecond electron microdiffraction, in which a short electron pulse with femtosecond-scale duration is focused into a micron-scale spot and used to obtain diffraction images to resolve ultrafast structural dynamics over a localized crystalline domain. In this letter, we report the experimental demonstration of time-resolved mega-electron-volt electron microdiffraction which achieves a 5 µm root-mean-square (rms) beam size on the sample and a 110 fs rms temporal resolution. Using pulses of 10k electrons at 4.2 MeV energy with a normalized emittance 3 nm-rad, we obtained high quality diffraction from a single 10 µm paraffin (C44H90) crystal. The phonon softening mode in optical-pumped polycrystalline Bi was also time-resolved, demonstrating the temporal resolution limits of the instrument. This new characterization capability will open many research opportunities in material and biological sciences.

Atomistic structural ensemble refinement reveals non-native structure stabilizes a sub-millisecond folding intermediate of CheY.

The dynamics of globular proteins can be described in terms of transitions between a folded native state and less-populated intermediates, or excited states, which can play critical roles in both protein folding and function. Excited states are by definition transient species, and therefore are difficult to characterize using current experimental techniques. Here, we report an atomistic model of the excited state ensemble of a stabilized mutant of an extensively studied flavodoxin fold protein CheY. We employed a hybrid simulation and experimental approach in which an aggregate 42 milliseconds of all-atom molecular dynamics were used as an informative prior for the structure of the excited state ensemble. This prior was then refined against small-angle X-ray scattering (SAXS) data employing an established method (EROS). The most striking feature of the resulting excited state ensemble was an unstructured N-terminus stabilized by non-native contacts in a conformation that is topologically simpler than the native state. Using these results, we then predict incisive single molecule FRET experiments as a means of model validation. This study demonstrates the paradigm of uniting simulation and experiment in a statistical model to study the structure of protein excited states and rationally design validating experiments.

Data systems for the Linac coherent light source.

The data systems for X-ray free-electron laser (FEL) experiments at the Linac coherent light source (LCLS) are described. These systems are designed to acquire and to reliably transport shot-by-shot data at a peak throughput of 5 GB/s to the offline data storage where experimental data and the relevant metadata are archived and made available for user analysis. The analysis and monitoring implementation (AMI) and Photon Science ANAlysis (psana) software packages are described. Psana is open source and freely available.

The mental health of patients with a chief complaint of chronic fatigue. A prospective evaluation and follow-up.

To determine the psychiatric morbidity of patients complaining of chronic fatigue, we undertook a prospective evaluation of 100 adults (65 women and 35 men; mean age, 41 years; and mean duration of chronic fatigue, 13 years). The study was conducted in an internal medicine outpatient clinic. In addition to a comprehensive medical evaluation, the patients were administered the 260-item Diagnostic Interview Schedule, a highly structured instrument that enabled the physician-interviewer to make accurate psychiatric diagnoses. A thorough follow-up examination was given an average of 8.4 months later. Sixty-six patients had one or more psychiatric disorders that were considered a major cause of their chronic fatigue (mood disorder, 47 patients; somatization disorder, 15 patients; and anxiety disorder, nine patients). Five patients had medical conditions that were considered a major cause of their fatigue. The complaint of chronic fatigue remained unexplained in 31 patients. In this prospective study, two thirds of cases of chronic fatigue appeared to be caused by psychiatric disorders. A thorough evaluation of the mental health of patients complaining of chronic fatigue could therefore provide pharmacologic and psychotherapeutic approaches and avoid unnecessary and costly medical investigations and therapies.

Effects of combination therapy with captopril and nifedipine in severe or resistant hypertension.

To assess the effect of potent vasodilator therapy in patients with severe or resistant hypertension, 10 patients underwent therapy with captopril and nifedipine alone and in combination. Blood pressure (BP), heart rate, and blood chemistry values were monitored for 4 weeks during captopril monotherapy and after 8 weeks during combination therapy with captopril and nifedipine. Compared with baseline, the BP decreased during captopril monotherapy (180 +/- 11/98 +/- 7 vs. 209 +/- 16/118 +/- 12 mm Hg; P less than 0.005). After the addition of nifedipine, the BP was further reduced (148 +/- 23/85 +/- 16 mm Hg), but there was no change in heart rate. In three patients not achieving the diastolic BP goal during combination therapy with dosing every 8 hours, automatic 24-hour ambulatory BP monitoring demonstrated lack of antihypertensive control for only the last 2 to 3 hours of the dosing interval. These data demonstrate that combination therapy with captopril and nifedipine is effective in patients with severe hypertension, but frequent dosing intervals are necessary for adequate antihypertensive control.

Depression and somatization in the chronic fatigue syndrome.

PURPOSE: To report the prevalence, clinical features, and diagnostic associations of the proposed chronic fatigue syndrome (CFS) in a cohort of patients with chronic fatigue and to assess the usefulness of a structured psychiatric interview for detecting previously unrecognized psychiatric morbidity in patients with CFS. PATIENTS AND METHODS: A consecutive sample of 200 adult patients with a chief complaint of chronic fatigue was prospectively evaluated in a referral-based clinic within a university general medicine practice. All patients received a thorough medical history, physical examination, diagnostic laboratory testing, and portions of the Diagnostic Interview Schedule, version III-A. The criteria for CFS were applied, and patients with CFS were compared with matched control subjects from the inception cohort. RESULTS: The 60 patients with CFS had similar likelihoods of current psychiatric disorders (78% versus 82%), active mood disorders (73% versus 77%), and preexisting psychiatric disorders (42% versus 43%) when compared with fatigued control subjects. Patients with CFS were more likely to have somatization disorder (p less than 0.001) and to attribute their illness to a physical cause (p less than 0.005) than fatigued controls. Patients with CFS also displayed functional symptoms, often lifelong, which are not part of the case definition of CFS. Depressive features in patients with CFS were similar to those of control subjects, but a trend toward suicidal behavior was noted. CONCLUSIONS: Patients with CFS have a high prevalence of unrecognized, current psychiatric disorders, which often predate their fatigue syndrome. Assessment of patients with CFS should include a structured psychiatric evaluation.

Yeast connection among 100 patients with chronic fatigue.

PURPOSE: Patients with the "yeast connection" are characterized by fatigue and multiple systemic symptoms. The purpose of our study was to compare patients with chronic fatigue who believed they had the yeast connection to patients with chronic fatigue without the yeast connection. PATIENTS AND METHODS: One hundred consecutive patients with a chief complaint of chronic fatigue were evaluated in a specialty clinic setting at the University of Connecticut Health Center. A complete history was obtained from each patient, and a 168-item review of systems and a complete physical examination were performed. RESULTS: Eight patients believed that their fatigue was due to chronic candidiasis. Of these eight, seven had psychiatric diagnoses that were judged to underlie their fatigue. Of the remaining 92 patients with chronic fatigue, 59 had underlying psychiatric diagnoses. We were unable to find historical, physical, or laboratory differences between chronic fatigue patients with or without the yeast connection. CONCLUSION: From this study and a review of the literature, we are unable to identify findings that are specific for the yeast connection.

Characterization of a variant erythrocyte surface antigen (VESA1) expressed by Babesia bovis during antigenic variation.

Babesia bovis, an intraerythrocytic, protozoal parasite of cattle, undergoes clonal antigenic variation (Allred DR, Cinque RM, Lane TJ, Ahrens KP. Infect Immun 1994;62:91-98). This ability could provide a mechanism by which the parasite escapes host immune defenses to establish chronic infection. Previous work identified two parasite-derived antigens of Mr 128,000 and 113,000 that were present on the surface of the infected erythrocyte and appeared to be associated with clonal antigenic variation (Allred DR, Cinque RM, Lane TJ, Ahrens KP. Infect Immun 1994;62:91 98). Two monoclonal antibodies (mAbs), 3F7.1H11 and 4D9.1G1, which recognize the variant erythrocyte surface antigen (VESA1) have been identified. These mAbs react only with the surface of erythrocytes infected with the B. bovis C9.1 clone in live-cell immunofluorescence assays. In both conventional and surface immunoprecipitations, the mAbs precipitate a variant antigen doublet that matches in mass the infected red blood cell (IRBC) surface antigens precipitated with bovine serum. In contrast, Western blot analysis revealed that only the Mr 128,000 polypeptide is recognized by the mAbs. Neither mAb recognizes antigenically variant progenitor or progeny parasite clones in any of the immunoassays, confirming the involvement of this antigen in rapid clonal antigenic variation. Failure to label this antigen with [9,10(n)-3H]myristic acid, [9,10(n)-3H]palmitic acid or D-[6-3H]glucosamine indicates that these polypeptides are neither N-glycosylated nor fatty acylated. Identity of the variant antigen recognized by the mAbs with that putatively identified with immune serum was confirmed by comparison of partial proteolytic digestion products. Unambiguous identification of the VESA1 antigen as a component of antigenic variation will facilitate characterization of the events leading to antigenic variation on the B. bovis-infected erythrocyte surface and its significance to parasite survival during chronic infection.

Depression among patients with a chief complaint of chronic fatigue.

The prevalence of mood disorders among patients with chronic fatigue was examined in a group of 100 adults who had experienced fatigue symptoms for an average of 13 years. Patients received a comprehensive history, physical and laboratory evaluation and completed the National Institute of Mental Health Diagnostic Interview Schedule and the Beck Depression Inventory (BDI). Among 44 patients with depressive illness, the onset of their first depressive episode was strongly associated with and preceded the onset of chronic fatigue. The BDI, fatigue history, demographic factors, and findings from the physical examination and laboratory had only modest success in discriminating those patients with depressive illness from other patients. We conclude that depressive illness is an important precursor of chronic fatigue.

Screening for somatization disorder in patients with chronic fatigue.

The current definition of Somatization Disorder requires the assessment of each of 35 symptoms, 13 of which have to be scored as meeting special criteria (e.g., not due to medical reasons) in order to make the diagnosis. The detailed questioning and probing about each symptom can be quite elaborate--hence the interest in developing briefer screening indexes. This study evaluated two sets of screening indexes for Somatization Disorder (those of Othmer and DeSouza and Swartz and colleagues) that had been previously developed in psychiatric and community samples. One hundred medical outpatients with chronic fatigue constituted the study sample. The patients underwent thorough medical evaluations and were administered the Diagnostic Interview Schedule (DIS) to make the psychiatric diagnoses. Of the two screening sets, the one developed in a psychiatric outpatient sample (Othmer and DeSouza's) had the best sensitivity. Although a screening index derived from the DIS interviews of this group of patients also had excellent sensitivity, we support the use of Othmer and DeSouza's index in medical outpatients with a chief complaint of chronic fatigue.

The low yield of physical examinations and laboratory investigations of patients with chronic fatigue.

Fatigue is a common symptom but guidelines for its appropriate evaluation are lacking. The authors prospectively studied 100 adults with a chief complaint of fatigue lasting at least 1 month in order to determine the diagnostic contribution of physical examinations and laboratory investigations. The evaluations were performed in the specialized clinic of a faculty practice. Physical examinations produced diagnostic information in 2% of patients, and laboratory investigations elucidated the cause of fatigue in 5% of patients. Structured follow-up evaluations after an average interval of 10 months failed to reveal any new organic causes for the fatigue symptom. Minor laboratory abnormalities were relatively common but did not contribute to the diagnostic process and did not seem to influence the clinical outcome. The authors conclude that the traditional medical evaluation of patients complaining of chronic fatigue has a low yield in discovering treatable physical disorders.

Evaluation and management of patients with chronic fatigue.

Chronic fatigue is a common and disabling problem in primary care practice. The differential diagnosis of chronic fatigue is extensive and includes medical disorders, altered physiologic states (eg, pregnancy, exertion), psychiatric disorders, lifestyle derangements, drugs, and controversial entities (eg, chronic candidiasis, food allergies, environmental illness, and chronic fatigue syndrome). The most common diagnoses are psychiatric disorders, including mood, anxiety, and somatoform disorders. A comprehensive approach to diagnosis and management is necessary, including structured psychiatric interviewing, functional assessment, and elicitation of the patient's diagnostic beliefs. Patients often believe they are suffering from an organic medical disorder (eg, viral or immunologic) and resist psychiatric labelling of their symptoms and referral to mental health practitioners. Establishing and maintaining rapport, having a flexible approach, and demonstrating a personal concern for the patient is essential. Drug therapy for specific psychiatric and medical illnesses and cognitive-behavioral approaches for enhancing coping mechanisms are effective.

Risk rate neglect in decisions involving invasive diagnostic procedures.

To investigate whether the risk of life-threatening complications influence the decisions involving invasive diagnostic procedures, a study was conducted that focused on the use of coronary angiography and endomyocardial biopsy with risk rates of either 1% or 2%. The participants included 38 physicians from two university-affiliated hospitals. Of their 76 pairs of decisions, 53% were of the "risk-avoidance" type and 26% were of the "risk-taking" type. Only 13% of decisions were of the "risk-conscious" type. The practical implication of these biases can be substantial in real-life decisions regarding events with low-probability, but high-consequence risks.

Follow-up evaluation of horses after neonatal intensive care.

A follow-up study was conducted on 131 foals that were less than 7 days old when admitted to the University of Florida Veterinary Medical Teaching Hospital between 1981 and 1983. Of the 71 foals (54%) that survived to be discharged, 39 (55%) were alive at follow-up evaluation, 19 (27%) could not be located, and 13 (18%) had died. The owners of surviving foals were sent questionnaires and 72% responded. The horses were visited and examined, if geographically possible, and an age-matched stablemate or a sibling also was evaluated and used as a control. Thirteen foals (10% of total admitted) died 1 day to 2 years after discharge. Four (8%) died from suspected sequelae of their neonatal illness. Three other foals appeared stunted as yearlings, but by 2 years of age equaled or passed their stablemates and/or siblings in physical development. The owners' estimated value of the survivors averaged +29,812. The actual selling price of horses that went through sales ranged from +7,000 to +210,000. Most of the horses became useful, athletic adults; several have won major stakes races. All living foals appeared unaffected by the physiologic disorders and treatments they encountered as neonates and compared favorably with stablemates and siblings.

Effects of prepubertal gonadectomy on physical and behavioral development in cats.

OBJECTIVE: To determine the effect of prepubertal gonadectomy on physical and behavioral development in cats. DESIGN: Prospective controlled study of kittens randomly assigned to 3 treatment groups: group 1, neutered at 7 weeks of age; group 2, neutered at 7 months of age; and group 3, sexually intact controls. ANIMALS: 31 clinically normal male and female kittens. PROCEDURE: Age at distal radial physeal closure and mature radius length were determined radiographically. Six behavioral characteristics were recorded monthly. At 1 year of age, body weight was recorded and thickness of the falciform ligament was measured from a lateral abdominal radiographic view. Secondary sex characteristics were also examined at 1 year of age. RESULTS: There were no differences between group-1 and group-2 cats for any of the study variables. Sexually intact cats (group 3) weighted significantly less than group-2 cats and had less falciform fat and earlier distal radial physeal closure than cats of both neutered groups. Group-3 cats manifested greater intraspecies aggression, less affection, and greater development of secondary sex characteristics than neutered cats. CLINICAL IMPLICATIONS: Neutering cats at 7 weeks of age had similar effects on physical and behavioral development, compared with neutering at the more traditional age of 7 months. These data lend support to the concept of prepubertal gonadectomy, already performed by many animal shelters/humane organizations, as a method of enhancing the effectiveness of pet population control programs.

Diazepam and succinylcholine chloride for restraint of the American alligator.

Diazepam followed by succinylcholine chloride was administered intramuscularly to 26 healthy mature female alligators on 2 occasions. The mean diazepam dosage was 0.37 mg/kg (range, 0.22 mg/kg to 0.62 mg/kg) and the mean succinylcholine chloride dosage was 0.24 mg/kg (range, 0.14 mg/kg to 0.37 mg/kg). This drug combination reduced stress and allowed adequate immobilization for restraint and handling. The reduced drug volume, low dosage of succinylcholine chloride required, short induction period, maintenance of respiration, and adequate degree of immobilization make this drug combination a good alternative to the use of muscle relaxants alone in chemical restraint of alligators.