Ptychographic amplitude and phase reconstruction of bichromatic vortex beams.

We experimentally demonstrate that ptychographic coherent diffractive imaging can be used to simultaneously characterize the amplitude and phase of bichromatic orbital angular momenta-shaped vortex beams, which consist of a fundamental field, together with its copropagating second-harmonic field. In contrast to most other orbital angular momentum characterization methods, this approach solves for the complex field of a hyperspectral beam. This technique can also be used to characterize other phase-structured illumination beams, and, in the future, will be able to be extended to other complex fields in the extreme ultraviolet or X-ray spectral regions, as well as to matter waves.

Isolated broadband attosecond pulse generation with near- and mid-infrared driver pulses via time-gated phase matching.

We present a theoretical analysis of the time-gated phase matching (ionization gating) mechanism in high-order harmonic generation for the isolation of attosecond pulses at near-infrared and mid-infrared driver wavelengths, for both few-cycle and multi-cycle driving laser pulses. Results of our high harmonic generation and three-dimensional propagation simulations show that broadband isolated pulses spanning from the extreme-ultraviolet well into the soft X-ray region of the spectrum can be generated for both few-cycle and multi-cycle laser pulses. We demonstrate the key role of absorption and group velocity matching for generating bright, isolated, attosecond pulses using long wavelength multi-cycle pulses. Finally, we show that this technique is robust against carrier-envelope phase and peak intensity variations.

Phase matching effects in high harmonic generation at the nanometer scale.

Plasmon resonances are known to amplify the electromagnetic fields near metallic nanostructures, providing a promising scheme to generate extreme-ultraviolet harmonics using low power drivings. During high-order harmonic generation (HHG), the driving and harmonic fields accumulate a phase difference as they propagate through the target. In a typical set-up -a laser focused into a gas jet- the propagation distances amount to several wavelengths, and the cumulative phase-mismatch affects strongly the efficiency and properties of the harmonic emission. In contrast, HHG in metallic nanostructures is considered to overcome these limitations, as the common sources of phase mismatch -optical density and focusing geometry- are negligible for subwavelength propagation distances. We demonstrate that phase matching still plays a relevant role in HHG from nanostructures due to the non-perturbative character of HHG, that links the harmonic phase to the intensity distribution of the driving field. Our computations show that widely used applications of phase matching control, such as quantum path selection and the increase of contrast in attosecond pulse generation, are also feasible at the nanoscale.

Brain injury biomarkers in the setting of cardiac surgery: Still a world to explore.

BACKGROUND: Brain injury is an important, potentially devastating, complication in cardiac surgery. A significant number of patients suffer perioperative complications involving the central nervous system. Clinical manifestations of brain injury are associated with significantly increased mortality, morbidity and health resource utilization. Serum biomarkers have been studied in cardiac surgery to measure the degree and incidence of brain injury and to improve patient management. METHODS: All relevant studies were identified by computerized searches of PubMed using the following Medical Subject Headings and keywords term: biomarker, cardiac surgery, brain injury and neurological complication. RESULTS: The biomarkers that appear to be better indicators of brain injury severity in cardiac surgery and its consequences are S100B protein, neuron-specific enolase, glial fibrillary acidic protein, tau protein, matrix metalloproteinase-9, ubiquitin C terminal hydroxylase-L1 and neurofilaments. CONCLUSIONS: These biomarkers, independently of clinical and radiological findings, show global cerebral situation at the cellular level and the degree of brain dysfunction. However, up to date, there is no biomarker entirely suitable for the detection of brain injury after cardiac surgery.

Carrier-envelope-phase insensitivity in high-order harmonic generation driven by few-cycle laser pulses.

We present evidence for self-stabilization of the relative spectral phase of high-order harmonic emission against intensity variations of the driving field. Our results demonstrate that, near the laser focus, phase matching of the harmonic field from a macroscopic target can compensate for the intensity dependence of the intrinsic phase of the harmonics emitted by a single radiator. As a consequence, we show experimentally and theoretically the insensitivity of the harmonic spectra produced at the laser focus against variations of the carrier-envelope phase (CEP) of a sub-two-cycle driving field. In addition, the associated attosecond pulse trains exhibit phase locking against CEP changes of the few-cycle driver.

Zeptosecond high harmonic keV x-ray waveforms driven by midinfrared laser pulses.

We demonstrate theoretically that the temporal structure of high harmonic x-ray pulses generated with midinfrared lasers differs substantially from those generated with near-infrared pulses, especially at high photon energies. In particular, we show that, although the total width of the x-ray bursts spans femtosecond time scales, the pulse exhibits a zeptosecond structure due to the interference of high harmonic emission from multiple reencounters of the electron wave packet with the ion. Properly filtered and without any compensation of the chirp, regular subattosecond keV waveforms can be produced.

Improving the electrostatic design of the Jefferson Lab 300 kV DC photogun.

The 300 kV DC high voltage photogun at Jefferson Lab was redesigned to deliver electron beams with a much higher bunch charge and improved beam properties. The original design provided only a modest longitudinal electric field (Ez) at the photocathode, which limited the achievable extracted bunch charge. To reach the bunch charge goal of approximately few nC with 75 ps full-width at half-maximum Gaussian laser pulse width, the existing DC high voltage photogun electrodes and anode-cathode gap were modified to increase Ez at the photocathode. In addition, the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the non-symmetric nature of the inverted insulator photogun design. We present the electrostatic design of the original photogun and the modified photogun and beam dynamics simulations that predict vastly improved performance. We also quantify the impact of the photocathode recess on beam quality, where recess describes the actual location of the photocathode inside the photogun cathode electrode relative to the intended location. A photocathode unintentionally recessed/misplaced by sub-millimeter distance can significantly impact the downstream beam size.

[Differential characteristics of patients with acute coronary syndrome without ST-segment elevation compared to those with transient ST-segment elevation]. / Características diferenciales de los pacientes con síndrome coronario agudo sin elevación del segmento ST con respecto a los que tienen elevación transitoria del segmento ST.

OBJECTIVE: To evaluate different characteristics of patients with acute coronary syndrome (ACS) without ST-segment elevation compared with transient St-segment elevation. DESIGN: An observational, prospective study. SETTING: A 12-bed coronary care unit. PATIENTS: Consecutive patients of ACS without persistent ST-segment elevation. MAIN VARIABLES OF INTEREST: The population was divided intro 2 groups according to the presence of transient ST-segment elevation. Variables of interest were age, cardiovascular risk factors, troponin I and glucose concentrations on admission, coronary anatomy, left ventricular ejection fraction, inhospital mortality and drugs. RESULTS: Patients identified as ACS with transient ST-segment elevation were significantly younger, smokers and predominantly male. At the same time, they showed a minor peak elevation of troponin I, a higher ejection fraction and, mainly single-vessel coronary disease. CONCLUSIONS: Patients with ACS with transient ST-segment elevation differ in the type of population, myocardial damage and coronary angiographic results with respect to patients with ACS without ST-segment elevation. More research is needed to clarify whether these differences imply a different therapeutic approach.

Treatment of refractory posterior uveitis with infliximab: a 7-year follow-up study.

OBJECTIVE: To describe, in a 7-year follow-up study, the use of infliximab in patients with refractory posterior uveitis and scleritis. METHODS: A 7-year follow-up case series study was performed. Patients with posterior uveitis and scleritis refractory to conventional therapies (steroids and at least one immunosuppressive agent) were included. Three infliximab intravenous doses of 5 mg/kg were administered at weeks 0, 2, and 6. Further infusions were allowed in patients undergoing a relapse of the uveitis after initial remission. All patients were followed up for at least 8 months. We defined uveitis improvement as an increase in the best-corrected visual acuity or an objective and significant improvement in retinal exudates and/or haemorrhages, cystoid macular oedema (CME), and vitreous haze. Infliximab-related adverse events, final prednisone doses, and the number of immunosuppressive agents used were recorded. A descriptive analysis was performed. RESULTS: A total of 11 patients (17 eyes were affected at baseline) were included, 63% were women, the mean age was 43+/-14 years, and the median follow-up was 80 months (p25-p75: 50-80). After infliximab treatment, six eyes maintained their basal visual acuity, nine eyes showed improvement, and two worsened (in the two patients diagnosed with choroiditis). Vitreous haze, active retinal vasculitis, and CME, but not chorioretinal lesions, improved in all patients. All patients tapered their daily steroid dose and the number of immunosuppressive agents. No infliximab-related adverse events were reported. CONCLUSIONS: Infliximab could be an effective and safe treatment in patients with posterior uveitis and scleritis refractory to conventional therapy.

Differences between rheumatology attending physicians and training residents in the management of rheumatoid arthritis in Spain.

OBJECTIVE: To evaluate the variability in the characteristics and management of rheumatoid arthritis (RA) patients between rheumatology attending physicians and training residents in Spain. METHODS: A retrospective medical record (MR) review was performed in a probabilistic sample of 1379 RA patients from 46 centres distributed in 16 of the 19 autonomous communities (AC) of Spain. RA patients' sociodemographic and clinical characteristics, healthcare resources use, and their single responsible physician's (defined as an identifiable single physician who attended the patient in more than 75% of visits) characteristics were recorded following a standardized protocol. Multivariate analyses were performed to assess differences in the characteristics and management of RA patients between attending physicians and training residents. RESULTS: A total of 1205 RA patients had a single responsible physician and were analysed (nearly 75% women with rheumatoid factor positive and more than 25% with persistent active disease), 49 of whom were followed by training residents and 1156 by attending physicians. In the multivariate analyses, irrespective of patient and disease characteristics, training residents' patients reported more hospital admissions, laboratory tests, and imaging techniques compared to attending physicians. Training residents also less frequently used combined therapy with disease-modifying antirheumatic drugs (DMARDs). CONCLUSION: Training residents and attending physicians differ in RA patients' care. More efforts in training programmes are necessary to guarantee proper RA management and to improve the profile of the future rheumatologists.

Electrostatic design and conditioning of a triple point junction shield for a -200 kV DC high voltage photogun.

Nuclear physics experiments performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Lab require a DC high voltage photogun to generate polarized electron beams from GaAs photocathodes. The photogun uses a tapered ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. Increasing the operating voltage from nominal -130 kV to -200 kV will provide lower beam emittance, better transmission through injector apertures, and improved photocathode lifetime. This desire to increase the photogun operating voltage led to the design of a triple-point-junction shield electrode which minimizes the electric field at the delicate insulator-metal-vacuum interface and linearizes the potential across the insulator, thus reducing the risk of arcing along the ceramic insulator. This work describes the results obtained using COMSOL® electrostatic-field simulation software and presents the high voltage conditioning results of the upgraded -200 kV CEBAF photogun.

Monitoring of glycolytic activity secondary to ischaemia in knee replacement surgery. / Monitorización de la actividad glucolítica secundaria a isquemia en cirugía sustitutiva de rodilla.

OBJECTIVES: To non-invasively assess tissue lesion secondary to ischaemia applied during knee replacement surgery. Secondary objectives: to assess whether this lesion correlates with the duration of ischaemia and whether instrumental and gender variables influence it. MATERIAL AND METHODS: Prospective cohort study. Pre and postoperative serum lactate levels have been determined as an indicator of glycolytic activity secondary to ischaemia in 88 patients. Serum lactate determination was performed by reactive strips of enzymatic-amperometric detection on capillary blood. RESULTS: Preoperative serum lactate levels (mean and SD): 2.467±1.036 mmol/L. Postoperative serum lactate levels: 3.938±2.018 mmol/L. Ischaemia time 102.98±18.25minutes. Postoperative serum lactate levels were significantly higher than preoperative lactate levels. There are no statistical differences according to the time that the ischaemia was prolonged, gender or type of instrumentation used. CONCLUSIONS: In our study, postoperative serum lactate values were significantly higher than preoperative lactate values, with no correlation to the duration of ischaemia during knee replacement surgery.

High voltage performance of a dc photoemission electron gun with centrifugal barrel-polished electrodes.

The design and fabrication of electrodes for direct current (dc) high voltage photoemission electron guns can significantly influence their performance, most notably in terms of maximum achievable bias voltage. Proper electrostatic design of the triple-point junction shield electrode minimizes the risk of electrical breakdown (arcing) along the insulator-cable plug interface, while the electrode shape is designed to maintain <10 MV/m at the desired operating voltage aiming at little or no field emission once conditioned. Typical electrode surface preparation involves diamond-paste polishing by skilled personnel, requiring several weeks of effort per electrode. In this work, we describe a centrifugal barrel-polishing technique commonly used for polishing the interior surface of superconducting radio frequency cavities but implemented here for the first time to polish electrodes for dc high voltage photoguns. The technique reduced polishing time from weeks to hours while providing surface roughness comparable to that obtained with diamond-paste polishing and with unprecedented consistency between different electrode samples. We present electrode design considerations and high voltage conditioning results to 360 kV (∼11 MV/m), comparing barrel-polished electrode performance to that of diamond-paste polished electrodes. Tests were performed using a dc high voltage photogun with an inverted-geometry ceramic insulator design.

Early lymphocyte activation in elderly humans: impaired T and T-dependent B cell responses.

Immunosenescence is characterized by an increase in autoantibody production. Because both T and B cell stimulation are key events for producing antibodies, we investigated early T and B cell activation by means of CD23 and CD40L (two very early activation antigens). PBMC from elderly humans (EH) were studied following culture with either medium, anti-CD3mAb, rIL-4, or PMA + ionomycin. CD23 expression on elderly B cells after anti-CD3 challenge of PBMC, a reflect of T-dependent B cell activation, was clearly defective. Conversely, CD23 expression on EH B cells following activation with soluble factors as rIL-4 was preserved. CD40L expression was also impaired in EH T cells following anti-CD3 challenge. However, activation by means of PMA and/or ionomycin was preserved both in T cells (CD40L expression) and in B cells (CD23 expression). These results indicate that a defective T-dependent B cell activation related to defective T cell activation located between surface membrane and PKC/ionomycin function is an intrinsic characteristic of immunosenescence. We have not found intrinsic B-cell defects, and we conclude that the characteristically impaired early B cell activation in EH is mostly due to T cell defects.

Eye involvement in the spondyloarthropathies.

Eye inflammation, especially uveitis, is a prominent feature of spondyloarthropathies. Uveitis associated with ankylosing spondylitis and Reiter's syndrome usually is a unilateral acute anterior uveitis with a high tendency to recur sometimes in the contralateral eye. Uveitis associated with undifferentiated spondyloarthropathy, inflammatory bowel disease, and psoriasis may be less characteristic in its presentation, with a higher tendency to posterior pole involvement, bilaterality, and chronicity. Although acute anterior uveitis is grouped into the spectrum of human leukocyte antigen B27-related disease, other genetic and environmental factors including infections by gram-negative bacteria and gut inflammation can play a role in its pathogenesis. The prognosis of uveitis usually is excellent with topical treatment, and only those with posterior pole involvement or a high tendency to recur or to chronicity might benefit from immunosuppressive therapy.

[Community-acquired pneumonia: influence of the duration of intravenous antibiotic therapy on hospital stay and the cost-benefit ratio]. / Neumonía adquirida en la comunidad: influencia de la duración de la antibioterapia intravenosa en la estancia hospitalaria y relación coste/efectividad.

UNLABELLED: Intravenous antibiotic therapy (IVAT) is usually prescribed for patients hospitalized with community-acquired pneumonia (CAP). Studies have associated prolonged IVAT with longer hospital stays and higher costs. The aim of this study was to determine the factors that influence the expense generated by and mean stay of patients hospitalized for pneumonia, with special attention to the influence of IVAT duration. MATERIAL AND METHODS: One hundred twenty-five CAP patients admitted to the respiratory medicine wards of our hospital were randomly assigned to five different staff physicians. IVAT was prescribed following the norms of the Spanish Society of Respiratory Medicine and Chest Surgery (SEPAR). IVAT was withdrawn when the attending physician considered it appropriate. We collected epidemiological, comorbidity, clinical and analytical data. Complications were recorded and severity of CAP was classified using the model proposed by Fine. Follow-up care was given at an outpatient clinic until symptoms disappeared and chest films resolved. Multivariate analysis determined the factors predicting mean hospital stay and high cost. Costs were calculated based on data issued by the billing department. RESULTS: The mean cost of care was 307,274 pesetas, mean duration of IVAT was 5.8 days and mean hospital stay was 9.4 days. Multivariate analysis showed that cost was related to mean hospital stay and IVAT. Mean hospital stay was associated with IVAT, the presence of respiratory insufficiency and the day of the week when admission took place (with weekend admission leading to longer stays). CONCLUSIONS: The duration of IVAT in CAP influences mean hospital stay and cost, without adding any evident therapeutic benefit (in the group of patients selected). Recommendations for diagnosing and treating CAP may be advisable.

Human parvovirus B19, varicella zoster virus, and human herpesvirus-6 in mesenchymal stem cells of patients with osteoarthritis: analysis with quantitative real-time polymerase chain reaction.

OBJECTIVE: To investigate whether there is a possible viral transmission using mesenchymal stem cells (MSCs) in autologous or allogeneic transplantation in the context of osteoarthritis (OA) patients. The presence of parvovirus B19 (B19), varicella zoster virus (VZV), and human herpesvirus-6 (HHV-6) was studied in MSCs from bone marrow of patients with OA and healthy controls. METHODS: MSCs were prepared from bone marrow aspirates obtained from 18 patients undergoing joint replacement as a result of OA and from 10 healthy controls. DNA was extracted from primary MSCs' culture established from these cells and quantitative real-time polymerase chain reaction was performed to analyse the prevalence and viral load of B19, VZV and HHV-6. RESULTS: The prevalence of total viral DNA among patients with OA was 16.7% (3/18), with a mean viral load of 29.7 copies/microg of DNA. One out of 18 was positive for B19 (viral load, 61.2 copies/microg of DNA), two for VZV (mean viral load, 14.4 copies/microg of DNA), and none for HHV-6. The prevalence of total viral DNA in the control group was 20% (2/10), with a mean viral load of 13.4 copies/microg of DNA. Both positive results were of B19 parvoviruses. There were no statistically significant differences among patients and controls. CONCLUSIONS: This first approach to the viral prevalence in MSCs of bone marrow in OA patients and healthy controls seems to show a very low risk of viral transmission or reactivation in a possible MSCs' transplantation.

Characterization and regulation of CD69 expression on rheumatoid arthritis synovial fluid T cells.

OBJECTIVE: To study CD69+ synovial fluid (SF) T cells and the mechanisms regulating CD69 expression in rheumatoid arthritis (RA). METHODS: One or 2 color flow cytometry was used to determine CD69 and other surface markers. Cultures of SF T cells alone or mixed with autologous SF non-T cells were used for CD69 maintenance assays. RESULTS: SF T cells were enriched in CD69+. These cells were mainly CD3+, CD8+ and CD25-. CD69 was maintained on SF T cells cultured with SF non-T cells but not when the former were cultured alone or in the presence of different supernatants from RA SF T and non-T cells cultures with sustained CD69 expression. Pretreatment of T and non-T cells with anti-CD18 monoclonal antibody inhibited CD69 expression, while paraformaldehyde-"fixed" non-T cells effectively maintained it. CONCLUSION: SF T cells exhibit a phenotype with evidence of past and recent activation. Our studies demonstrate that most of the recently activated SF T cells are CD8+. We also found that continuous cell-to-cell interaction between T and non-T cells are responsible for the maintenance of this particular state of activation of SF T cells.