ABSTRACT
We propose a scheme to explore regimes of strong-field quantum electrodynamics (SF QED) otherwise unattainable with the currently available laser technology. The scheme relies on relativistic plasma mirrors curved by radiation pressure to boost the intensity of petawatt-class laser pulses by Doppler effect and focus them to extreme field intensities. We show that very clear SF QED signatures could be observed by placing a secondary target where the boosted beam is focused.
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AIM: To investigate the effect of colour scale choice on diagnostic performance in the interpretation of medical images. MATERIALS AND METHODS: Twelve clinicians interpreted 210 myocardial computed tomography (CT) perfusion (CTP) examinations, and nine clinicians interpreted 165 magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) prostate images. In three separate sessions, each participant read the same image set using greyscale, hot-iron, and rainbow scales, respectively. Participants scored their level of confidence for tumour presence in the ADC study, and for ischaemia in the CTP study, from 0 to 100. The area under the receiver operating characteristic (ROC) curve (AUC) was used as the performance metric. For cases that scored >50, CTP readers' agreement on the ischaemic transmural extent was analysed, and ADC map readers' selected values and coordinates for the lowest ADC within the detected tumour were compared across different colour scales. RESULTS: For CTP detection, the AUC was up to 0.10 higher with greyscale, 0.67±0.02 (standard error), compared to rainbow, 0.56±0.02, and detection with hot-iron was in between (0.61±0.03). For ischaemic transmural lesion categorisation, observed inter-reader agreement was highest with greyscale for category 25-50%. There is a small tendency for rainbow and greyscale to outperform hot-iron in the detection of prostate tumours. The selected lowest ADC value and pixel localisation was similar with all colour scales. CONCLUSIONS: The present findings suggest that colour visualisation has a measurable effect on CTP and ADC performance. Further investigation is necessary to determine the magnitude of the effect in diagnostic tasks.
Subject(s)
Heart/diagnostic imaging , Prostate/diagnostic imaging , Tomography, X-Ray Computed , Adult , Color , Female , Humans , Magnetic Resonance Imaging , Male , Myocardial Ischemia/diagnostic imaging , Prostatic Neoplasms/diagnostic imaging , Tomography, X-Ray Computed/methodsABSTRACT
The emission of high-order harmonics in the extreme ultraviolet range from the interaction of a short, intense laser pulse with a grating target is investigated experimentally. When resonantly exciting a surface plasmon, both the intensity and the highest order observed for the harmonic emission along the grating surface increase with respect to a flat target. Harmonics are obtained when a suitable density gradient is preformed at the target surface, demonstrating the possibility to manipulate the grating profile on a nanometric scale without preventing the surface plasmon excitation. In support of this, the harmonic emission is spatiotemporally correlated to the acceleration of multi-MeV electron bunches along the grating surface. Particle-in-cell simulations reproduce the experimental results and give insight on the mechanism of high harmonic generation in the presence of surface plasmons.
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The generation of energetic electron bunches by the interaction of a short, ultraintense (I>10(19) W/cm(2)) laser pulse with "grating" targets has been investigated in a regime of ultrahigh pulse-to-prepulse contrast (10(12)). For incidence angles close to the resonant condition for surface plasmon excitation, a strong electron emission was observed within a narrow cone along the target surface, with energy spectra peaking at 5-8 MeV and total charge of â¼100 pC. Both the energy and the number of emitted electrons were strongly enhanced with respect to simple flat targets. The experimental data are closely reproduced by three-dimensional particle-in-cell simulations, which provide evidence for the generation of relativistic surface plasmons and for their role in driving the acceleration process. Besides the possible applications of the scheme as a compact, ultrashort source of MeV electrons, these results are a step forward in the development of high-field plasmonics.
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INTRODUCTION: C-reactive protein (CRP) levels rise during inflammatory processes and have been ordered for rheumatic disease follow-up since the 1950s. The number of tests ordered in the emergency setting has increased, but without evident improvement in medical care quality. OBJECTIVE: To determine the pattern of CRP determinations in the emergency department (ED) of a university hospital in Sao Paulo, Brazil, and to evaluate the effect of an intervention with staff and students about the best use of the test in the ED. METHODS: Data regarding CRP testing requests, related diagnoses and the number of monthly consultations in the hospital ED were analysed before and after the intervention. Because of an increase in CRP measurement requests from 2007 to 2009, the author started discussing the role of CRP determinations in the medical decision-making process in early 2010. Staff and faculty members openly discussed the pattern of requests in the hospital and related current medical literature. During 2010, the medical staff worked as multipliers to change the behaviour of new students and residents. The results of the first 4 months after the intervention were presented at another general meeting in July 2010. RESULTS: From 2007 to 2009, there were 11,786 CRP measurement requests with a clear exponential trend. After the intervention, during the calendar year 2010, there was a 48% reduction in adjusted annual CRP requests. Pneumonia, fever and urinary tract infections were the most common reasons for CRP requests. DISCUSSION: Inexpensive, well-directed, interactive educational interventions may affect professional behaviour and curb rates of laboratory tests.
Subject(s)
C-Reactive Protein/analysis , Clinical Chemistry Tests/statistics & numerical data , Emergency Service, Hospital/statistics & numerical data , Infections/diagnosis , Acute Disease , Biomarkers/analysis , Brazil , Hospitals, University , Humans , Regression AnalysisABSTRACT
PURPOSE: This study investigated the radiation dose to surgeon eye lens for single procedure and normalised to exposure parameters for eight selected neuroradiology, cardiovascular and radiology interventional procedures. METHODS: The procedures investigated were diagnostic study, Arteriovenous Malformations treatment (AVM) and aneurysm embolization for neuroradiology procedures, Coronary Angiography and Percutaneous Transluminal Coronary Angioplasty (CA-PTCA), Pacemaker and Implantable Cardioverter-Defibrillator implantation (PM-ICD), Endovascular Aortic Repair (EVAR) and Fenestrated Endovascular Aortic Repair (FEVAR) for cardiovascular and electrophysiology procedures. CT-guided lung biopsy was also monitored. All procedures were performed with table-mounted and ceiling-suspended shields (0.5 mm lead equivalent thickness), except for FEVAR and PM-ICD where only a table mounted shield was present, and CT-guided lung biopsy where no shield was used. Dose assessment was performed using a dosemeter positioned close to the most exposed eye of the surgeon, outside the protective eyewear. RESULTS: The surgeon most exposed eye lens median Hp(3) equivalent dose for a single procedure, without protective eyewear contribution, was 18 µSv for neuroradiology diagnostic study, 62 µSv for AVM, 38 µSv for aneurysm embolization, 33 µSv for CA-PTCA, 39 µSv for PM-ICD, 49 µSv for EVAR, 2500 µSv for FEVAR, 153 µSv for CT-guided lung biopsy. CONCLUSIONS: In interventional procedures, the 20 mSv/year dose limit for surgeon eye lens exposure might be exceeded if shields or protective eyewear are not used. Surgeon eye lens doses, normalised to single procedures and to exposure parameters, are a valuable tool for determining appropriate radiation protection measures and dedicated eye lens dosemeter assignment.
Subject(s)
Aneurysm , Lens, Crystalline , Humans , Endovascular Aneurysm Repair , LungABSTRACT
Radioprotection of the eye lens of medical staff involved in Surgical procedures is a subject of international debates since ICRP recommended, on 2011, a lower equivalent dose limit for the lens of the eye. In this work we address the effectiveness of different models of X-ray protective eyewear by relating actual dosimetry measurements to an ad hoc developed mathematical model, in order to disentangle the contribution of geometrical factors and shield capabilities. Phantom irradiation was carried out in fixed exposure conditions in angiographic room: we found that measured Dose Reduction Factors (DRF) strongly depend on the ergonomics of the investigated eyewear. Actually a very poor DRF was observed in the case of a glass model in spite of its high nominal attenuation, whereas a protective tool with low shielding capabilities such a visor resulted much more effective as a consequence of is shape (i.e. extended geometric protection of the eye lens). Our work highlights the need of the introduction of a specific parameter to quantify the effectiveness of the protection tools and able to predict their DRF by taking into account the geometry of the clinical condition of exposure. Aiming at making steps forward the standardization of the guidelines concerning the features of eye protective tools, we developed a simple mathematical model describing the eye lens irradiation geometry which allows the introduction, for each eyewear, of a comprehensive parameter, the Eye Protection Effectiveness (EPE), that, for any defined clinical irradiation condition and glass shielding capabilities and shape, defines the overall effective X-ray protection of the eyewear.
Subject(s)
Eye Injuries/prevention & control , Lens, Crystalline/radiation effects , Radiation Injuries/prevention & control , Radiation Protection/methods , Radiography/instrumentation , Eye Protective Devices , Hospitals , Humans , Models, Theoretical , Phantoms, Imaging , Radiation Dosage , Radiation Exposure/prevention & control , Scattering, Radiation , X-RaysABSTRACT
Ion beam analysis techniques are among the most powerful tools for advanced materials characterization. Despite their growing relevance in a widening number of fields, most ion beam analysis facilities still rely on the oldest accelerator technologies, with severe limitations in terms of portability and flexibility. In this work we thoroughly address the potential of superintense laser-driven proton sources for this application. We develop a complete analytical and numerical framework suitable to describe laser-driven ion beam analysis, exemplifying the approach for Proton Induced X-ray/Gamma-ray emission, a technique of widespread interest. This allows us to propose a realistic design for a compact, versatile ion beam analysis facility based on this novel concept. These results can pave the way for ground-breaking developments in the field of hadron-based advanced materials characterization.
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In this work we investigate electron heating induced by intense laser interaction with micrometric flat solid foils in the context of laser-driven ion acceleration. We propose a simple law to predict the electron temperature in a wider range of laser parameters with respect to commonly used existing models. An extensive two-dimensional (2D) and 3D numerical campaign shows that electron heating is due to the combined actions of j×B and Brunel effect. Electron temperature can be well described with a simple function of pulse intensity and angle of incidence, with parameters dependent on pulse polarization. We then combine our model for the electron temperature with an existing model for laser-ion acceleration, using recent experimental results as a benchmark. We also discuss an exploratory attempt to model electron temperature for multilayered foam-attached targets, which have been proven recently to be an attractive target concept for laser-driven ion acceleration.
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Multi-center epidemiological studies must ascertain that their measurements are accurate and reliable. For laboratory measurements, reliability can be assessed through investigation of reproducibility of measurements in the same individual. In this paper, we present results from the quality control analysis of the baseline laboratory measurements from the ELSA-Brasil study. The study enrolled 15,105 civil servants at 6 research centers in 3 regions of Brazil between 2008-2010, with multiple biochemical analytes being measured at a central laboratory. Quality control was ascertained through standard laboratory evaluation of intra- and inter-assay variability and test-retest analysis in a subset of randomly chosen participants. An additional sample of urine or blood was collected from these participants, and these samples were handled in the same manner as the original ones, locally and at the central laboratory. Reliability was assessed with the intraclass correlation coefficient (ICC), estimated through a random effects model. Coefficients of variation (CV) and Bland-Altman plots were additionally used to assess measurement variability. Laboratory intra and inter-assay CVs varied from 0.86% to 7.77%. From test-retest analyses, the ICCs were high for the majority of the analytes. Notably lower ICCs were observed for serum sodium (ICC=0.50; 95%CI=0.31-0.65) and serum potassium (ICC=0.73; 95%CI=0.60-0.83), due to the small biological range of these analytes. The CVs ranged from 1 to 14%. The Bland-Altman plots confirmed these results. The quality control analyses showed that the collection, processing and measurement protocols utilized in the ELSA-Brasil produced reliable biochemical measurements.
Subject(s)
Laboratories/standards , Quality Control , Adult , Brazil , Humans , Longitudinal Studies , Observer Variation , Reference Standards , Reproducibility of ResultsABSTRACT
The acceleration of dense targets driven by the radiation pressure of high-intensity lasers leads to a Rayleigh-Taylor instability (RTI) with rippling of the interaction surface. Using a simple model it is shown that the self-consistent modulation of the radiation pressure caused by a sinusoidal rippling affects substantially the wave vector spectrum of the RTI, depending on the laser polarization. The plasmonic enhancement of the local field when the rippling period is close to a laser wavelength sets the dominant RTI scale. The nonlinear evolution is investigated by three-dimensional simulations, which show the formation of stable structures with "wallpaper" symmetry.
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In an experiment at the laser facility ECLIPSE of the CELIA laboratory, University of Bordeaux, we measure the reflectivity of spherically bent crystals that are commonly used to investigate the propagation of fast electrons through the Kα radiation they generate in matter. The experimental reflectivity compares well with predictions from a ray-tracing code that takes into account the specific geometry, although the crystals seem to suffer from aging problems.
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An investigative study was carried out for 2 years involving 124 randomly selected early postmenopausal women with spine bone mineral density (BMD) below the mean value of a normal premenopausal subject. After random division into three groups, the first 42 patients were treated with transcutaneous 17-beta-estradiol (50 micrograms daily), the second 42 were treated with cyclical intravenous clodronate (200 mg/month iv infusion), and the third group of 40 (controls) was left untreated. After 2 years, the total drop in BMD within the control group was more than 7% as opposed to the values of -0.14% +/- 0.93 in the estradiol group and 0.67% +/- 0.84 in the clodronate group. A change in BMD of < 1% was considered satisfactory, and this result was obtained in 32% of the controls, in 79% of the estradiol group where the percentage change in BMD moderately correlated with serum estradiol levels (r = 0.399), and in 90% of the clodronate-treated patients, in whom the percentage change in BMD inversely correlated with basal values of markers of bone turnover. Both estrogen and clodronate prevent postmenopausal bone loss. The response to transcutaneous hormone replacement therapy may be influenced by transcutaneous absorption and by a lower sensitivity to estrogen. Response to cyclical clodronate seems to be influenced by the rate of bone turnover. An interdosage interval ranging from 2-4 weeks appears suitable for most patients.
Subject(s)
Bone Density/drug effects , Clodronic Acid/therapeutic use , Estradiol/therapeutic use , Estrogen Replacement Therapy , Osteoporosis, Postmenopausal/prevention & control , Absorptiometry, Photon , Administration, Cutaneous , Adult , Analysis of Variance , Biomarkers/blood , Biomarkers/urine , Bone Development/drug effects , Clodronic Acid/administration & dosage , Clodronic Acid/pharmacology , Estradiol/administration & dosage , Estradiol/blood , Estradiol/pharmacology , Female , Follow-Up Studies , Humans , Infusions, Intravenous , Lumbar Vertebrae/drug effects , Lumbar Vertebrae/physiology , Medroxyprogesterone/administration & dosage , Medroxyprogesterone/pharmacology , Medroxyprogesterone/therapeutic use , Middle Aged , Osteoporosis, Postmenopausal/drug therapy , Skin Absorption/drug effects , Skin Absorption/physiologyABSTRACT
To investigate the site and mode of action of progesterone in inducing gonadotropin release, the effects of catecholamine-depleting (methyldopa) or dopamine agonist (bromocriptine) drugs on progesterone positive feedback and the gonadotropin response to a centrally acting noradrenergic drug (clonidine) were evaluated in estrogen-primed postmenopausal women. Progesterone administration induced a significant rise in LH, FSH, and PRL serum levels in the control group. Bromocriptine administration was followed by a marked suppression of PRL release but did not modify the gonadotropin response to progesterone. Methyldopa pretreatment significantly reduced the progesterone-induced LH surge, while PRL release was unaffected. After estrogen priming, clonidine administration did not result in an increase in serum LH or FSH concentrations. The dissociated responses of LH and PRL in bromocriptine-pretreated subjects and the significant reduction of the LH rise after progesterone in methyldopa-pretreated women seem to invalidate the hypothesis that a fall in endogenous dopamine is responsible for progesterone positive feedback and suggest that neural noradrenergic mechanisms are involved in progesterone-induced gonadotropin release. The ineffectiveness of a centrally acting noradrenergic agonist in inducing gonadotropin rise provides indirect evidence that an increased pituitary responsiveness may also be involved in progesterone positive feedback.
Subject(s)
Bromocriptine , Gonadotropins, Pituitary/blood , Menopause , Methyldopa , Progesterone , Aged , Clonidine , Ethinyl Estradiol , Feedback , Female , Follicle Stimulating Hormone/blood , Humans , Luteinizing Hormone/blood , Middle Aged , Prolactin/bloodABSTRACT
We report the results of long-term cyclical clodronate therapy (200 mg IV infusion every 3 weeks) on 235 women with postmenopausal osteoporosis recruited over 6 years. A retrospective analysis of clinical and instrumental findings in 183 postmenopausal osteoporotic patients was used as control data. Clodronate was well-tolerated and compliance was good. Bone mineral density (BMD) increased significantly and the upward trend persisted for all 6 years of therapy (5.69 +/- 0.184%) vs. controls: -1.47% +/- 0.813%, p <0.0001). The increase in BMD was greater in the 145 patients without vertebral fractures before starting clodronate. From year 3 onward clodronate reduced the incidence of new vertebral fractures. In closed subsets of patients and controls monitored for 3 and 4 years, respectively, the number of patients developing new vertebral fractures fell significantly in the clodronate group (two-sided p value = 0.0671 and p <0.0026, respectively). This trend was more marked in patients who were fracture-free at the beginning of each year. Cyclical clodronate is a safe and effective therapy for established osteoporosis, but clinical trials are necessary to compare its efficacy versus continuous therapy and, as in the case of the other bisphosphonates, to investigate its mechanisms of action in depth.
Subject(s)
Bone Density/drug effects , Clodronic Acid/therapeutic use , Spinal Fractures/prevention & control , Adult , Aged , Clodronic Acid/adverse effects , Drug Administration Schedule , Female , Follow-Up Studies , Humans , Incidence , Infusions, Intravenous , Middle Aged , Retrospective Studies , Spinal Fractures/epidemiologyABSTRACT
Response of serum levels of gonadotropins and prolactin to doses of estrogen and progesterone was measured in a patient with the complete form of androgen insensitivity, ie, testicular feminization. Before gonadectomy a single 2.5-mg dose of estradiol benzoate (E2B) produced a decrease in gonadotropin levels. Gonadectomy resulted in a rise of serum levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) but had no effect on levels of prolactin. The following results were obtained after gonadectomy: During low-dosage therapy with ethinyl estradiol (EE) a single 2.5-mg dose of E2B produced a decrease in FSH and LH levels, no LH surge, and a small rise in prolactin levels. With a tenfold higher EE priming, the same dose of E2B provoked an LH surge; progesterone administration produced FSH, LH, and prolactin release. However, progesterone priming blocked the positive feedback of estradiol and enhanced its negative feedback. Pituitary sensitivity ot nonandrogenic steroids appears to be normal in cases of testicular feminization. Under this condition, after gonadectomy, the dynamics of gonadotropins and prolactin in response to estrogens or progesterone administration are similar to those in normal women and suggest that aromatization products of testosterone do not produce any irreversible effects on neuroendocrine differentiation of androgen-insensitive patients
Subject(s)
Androgen-Insensitivity Syndrome/blood , Estradiol/pharmacology , Follicle Stimulating Hormone/blood , Luteinizing Hormone/blood , Progesterone/pharmacology , Prolactin/blood , Adult , Androgen-Insensitivity Syndrome/surgery , Female , Gonads/surgery , Humans , Male , Testosterone/bloodABSTRACT
AIM: Renal functional reserve (RFR), resulting from an increase in glomerular filtration (GFR) after protein load, is a matter of debate. In kidney transplant recipients most studies have failed to show conclusive results, reporting either the absence, the reduction or the presence of renal reserve in normo-functioning kidneys. The aim of this study was to investigate RFR in kidney transplant patients as well as the possible hormonal vasoactive alterations underlying the reduction of renal reserve reported in some patients. PATIENTS AND METHODS: We studied 8 controls and 25 patients, the latter with no history of acute rejection for at least 12 months and GFR >50 ml/min. The 25 patients were divided into 2 groups based on the presence (10) or the absence (15) of RFR. RESULTS: Both the RFR group and the controls experienced a similar increase of GFR after oral protein load: 24.3 +/- 15.57% vs 24.4 +/- 10.8%. The group without RFR showed a paradoxical reduction of GFR after oral protein load: 13.3 +/- 13.2% (p <0.001). We analyzed the filtration fraction (FF) and observed that the group without RFR had higher values than the group with RFR and the controls: 0.35 +/- 0.11 vs 0.29 +/- 0.07 (p = 0.01) and vs 0.26 +/- 0.02 (p = 0.04). The hyperfiltration state observed in the group without RFR was sustained by a high level of thromboxane. The urine ratio TxB2/6ketoPgF1alpha was higher in the group without RFR than in the RFR group 0.78 +/- 0.2 vs 0.64 +/- 0.1 (p = 0.01). This ratio decreased only in the RFR group after a meat meal. In all the patients, changes of TxB2/6ketoPGF1alpha were inversely correlated to changes of GFR after a meat meal (r = -0.6, p = 0.01). CONCLUSIONS: In conclusion, these data demonstrate that kidney transplant recipients with good organ function can be grouped according to the presence of RFR. RFR appears to be inversely correlated with the TxB2/6ketoPGF1alpha ratio, and its decrease seems to be linked to the failure of thromboxane to decrease and prostacycline to increase after a meat meal.
Subject(s)
Arachidonic Acid/metabolism , Kidney Transplantation , Kidney/physiopathology , 6-Ketoprostaglandin F1 alpha/urine , Adolescent , Adult , Dietary Proteins/administration & dosage , Glomerular Filtration Rate , Humans , Middle Aged , Thromboxane B2/urineABSTRACT
ARDS is a life-threatening pulmonary disease with a rapidly progressive decline due mainly to multi-organ failure. Death occurs in 50-75% of ARDS cases. The diagnosis and therapy should start in the first six days of this fatal disease when mortality is at its lowest level. The 99mTc-DTPA-measured pulmonary alveolar epithelial permeability (PAEP) is strikingly increased in ARDS even in comparison to heavy smokers. Furthermore, surfactant inhalation has been shown to be of therapeutic value. In five ARDS patients with increased PAEP (T0.5 = 12% pred.) 20 mg/kg of aerosolized surfactant determined a dramatic improvement in blood gases and PAEP (51.8% pred.) No patient remained dependent on ventilatory treatment.
Subject(s)
Pulmonary Surfactants/administration & dosage , Respiratory Distress Syndrome/drug therapy , Technetium Tc 99m Pentetate/administration & dosage , Administration, Inhalation , Adult , Aerosols , Aged , Female , Humans , Male , Middle Aged , Permeability , Pulmonary Alveoli/physiopathology , Respiratory Distress Syndrome/diagnosisABSTRACT
In 13 healthy young adults, nasal mucociliary transport velocity was measured by means of albumine microsphere labeled with Tc99m as a tracer. M + ISD of clearance velocity values and of the half time radioactivity (T1/2) resulted to be respectively 1.02 + 0.22 cm/min and 1.07 + 0.24 min. A significant correlation (P less than 0.05) between half time clearance (T1/2) values of the radioactive particles and the mucociliary velocity ones could be detected, making T1/2 a reliable and rapidly obtainable parameter for determining nasal mucociliary function. Advantages and disadvantages of the different techniques are discussed.
Subject(s)
Diagnostic Techniques, Radioisotope/methods , Mucociliary Clearance , Technetium Tc 99m Aggregated Albumin , Adult , Female , Humans , Male , Saccharin , Time FactorsABSTRACT
BACKGROUND: The reinjection of autologous 131I-labelled low-density lipoprotein (LDL) followed by vascular scintigraphy has been used to investigate lipid-containing plaques, but no information is available on the early stages of plaques in hypertensives. Vascular scintigraphy after re-injection of autologous 131I-labelled LDL was used to investigate early atherosclerotic lesions visualized by sonography in the carotid arteries of patients with hypertension. PATIENTS AND METHODS: 10 male patients (4 smokers; mean age 56 +/- 8 years;) with early carotid atherosclerosis (mono- or bilateral; intima-media-thickness ranging from 1.5 to 3.5 mm) as shown by sonography were studied. All these normolipemic patients suffered from primary hypertension and were treated with diuretics. As controls 6 healthy male subjects (3 smokers; mean age 54 +/- 9 years;), with normal blood pressure and lipid pattern were recruited. RESULTS: Hot spots appeared in the areas with early atherosclerosis in 7 patients, while none were seen in controls. Positive kinetic curves were observed in 4 patients. No significant differences emerged in the target/non-target ratios. CONCLUSIONS: Vascular lipoprotein uptake in hypertensive patients is apparently late and rather limited; the uptake pattern may depend on plaque composition.