759 research outputs found
A Molecule‐Based Single‐Photon Source Applied in Quantum Radiometry
Single photon sources (SPSs) based on quantum emitters hold promise in
quantum radiometry as metrology standard for photon fluxes at the low light
level. Ideally this requires control over the photon flux in a wide dynamic
range, sub-Poissonian photon statistics and narrow-band emission spectrum. In
this work, a monochromatic single-photon source based on an organic dye
molecule is presented, whose photon flux is traceably measured to be adjustable
between 144 000 and 1320 000 photons per second at a wavelength of (785.6 +/-
0.1) nm, corresponding to an optical radiant flux between 36.5 fW and 334 fW.
The high purity of the single-photon stream is verified, with a second-order
autocorrelation function at zero time delay below 0.1 throughout the whole
range. Featuring an appropriate combination of emission properties, the
molecular SPS shows here application in the calibration of a silicon
Single-Photon Avalanche Detector (SPAD) against a low-noise analog silicon
photodiode traceable to the primary standard for optical radiant flux (i.e. the
cryogenic radiometer). Due to the narrow bandwidth of the source, corrections
to the SPAD detection efficiency arising from the spectral power distribution
are negligible. With this major advantage, the developed device may finally
realize a low-photon-flux standard source for quantum radiometry
A compact ultranarrow high-power laser system for experiments with 578nm Ytterbium clock transition
In this paper we present the realization of a compact, high-power laser
system able to excite the Ytterbium clock transition at 578 nm. Starting from
an external-cavity laser based on a quantum dot chip at 1156 nm with an
intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of
visible light at 578 nm via frequency doubling. The laser is locked with a 500
kHz bandwidth to a ultra-low-expansion glass cavity stabilized at its zero
coefficient of thermal expansion temperature through an original thermal
insulation and correction system. This laser allowed the observation of the
clock transition in fermionic Yb with a < 50 Hz linewidth over 5
minutes, limited only by a residual frequency drift of some 0.1 Hz/s
Revisione della letteratura sull’efficacia della manipolazione vertebrale nel trattamento dei pazienti con cefalea cervicogenica
Background: La cefalea cervicogenica è una cefalea causata da una disfunzione del rachide cervicale e dalle sue componenti ossee, discali e/o dei tessuti molli, solitamente accompagnata da dolore al collo. È una patologia frequente che colpisce lo 0,4-2,6% della popolazione generale. La manipolazione spinale è una tecnica manuale comunemente utilizzata come trattamento di questa patologia, anche se il dibattito sulla sua efficacia è ancora aperto.
Obiettivi: L’obiettivo di questa tesi è valutare l’efficacia della manipolazione vertebrale nel trattamento dei pazienti con cefalea cervicogenica.
Materiali e metodi: La ricerca bibliografica è stata condotta sulle banche dati PubMed e PEDro usando le parole chiave “cervicogenic headache” e “manipulation”. L’outcome primario è stato valutare l’efficacia delle manipolazioni sulla frequenza della cefalea.
Risultati: Degli articoli trovati tramite la ricerca sulle due banche dati, 5 sono risultati conformi ai criteri di inclusione. Gli studi selezionati sono tutti Trial Clinici Randomizzati Controllati, di buona qualità metodologica, valutati con la scala PEDro.
Conclusioni: I dati mostrano l’efficacia della manipolazione vertebrale nel trattamento di pazienti con cefalea cervicogenica
A new freeware raycasting tool combined with fluorescent coating to allow for object visibility
Abstract
Time resolved PIV encompassing moving and/or deformable objects interfering with the light source requires the employment of dynamic masking (DM). A few DM techniques have been recently developed, mainly in microfluidics and multiphase flows fields. Most of them require ad-hoc design of the experimental setup, and may spoil the accuracy of the resulting PIV analysis. A new DM technique is here presented which envisages, along with a dedicated masking algorithm, the employment of fluorescent coating to allow for accurate tracking of the object. We show results from measurements obtained through a validated PIV setup demonstrating the need to include a DM step even for objects featuring limited displacements. We compare the proposed algorithm with both a no-masking and a static masking solution. In the framework of developing low cost, flexible and accurate PIV setups, the proposed algorithm is made available through a freeware application able to generate masks to be used by an existing, freeware PIV analysis package.
Graphic abstrac
Serum Potassium Disorders Predict Subsequent Kidney Injury: A Retrospective Observational Cohort Study of Hospitalized Patients
Introduction: Electrolyte disorders are common findings in kidney diseases and might represent a useful biomarker preceding kidney injury. Serum potassium [K+] imbalance is still poorly investigated for association with acute kidney injury (AKI), and most evidence came from intensive care units. The aim of our study was to comprehensively investigate this association in a large, unselected cohort of hospitalized patients. Methods: We performed a retrospective observational cohort study on the inpatient population admitted to Fondazione Policlinico Universitario A. Gemelli IRCCS between January 1, 2010 and December 31, 2014, with inclusion of adult patients with at least 2 [K+] and 3 serum creatinine measurements who did not develop AKI during an initial 10-day window. The outcome of interest was in-hospital AKI. The exposures of interest were [K+] fluctuations and hypo (HoK) and hyperkalemia (HerK). [K+] variability was evaluated using the coefficient of variation. Cox proportional hazards regression models were used to obtain hazard ratios and 95% confidence intervals of the association between the exposures of interest and development of AKI. Results: About 21,830 hospital admissions from 18,836 patients were included in our study. During a median follow-up of 5 (interquartile range [IQR] 7) days, AKI was observed in 555 hospital admissions (2.9%); median time for AKI development was 5 (IQR 7) days. Higher [K+] variability was independently associated with increased risk of AKI with a statistically significant linear trend across groups (p value = 0.012). A significantly higher incidence of AKI was documented in patients with HerK compared with normokalemia. No statistically significant difference was observed between HoK and HerK (p value = 0.92). Conclusion: [K+] abnormalities including fluctuations even within the normal range are associated with development of AKI
Glutathione concentration and gamma-glutamyltransferase activity in water buffalo colostrum
Evidence is presented that the buffalo mammary gland contains enzymes that catalyse the synthesis and utilization of glutathione. A significant, inverse correlation (r = 0.79) was detected between colostrum gamma-glutamyltransferase (GGT) and glutathione (GSH), suggesting that the enzyme uses GSH as a substrate for its activity. A similar trend was shown in mammary gland homogenates (r = 0.75). Our results show that GSH is secreted into buffalo colostrum and suggest that the enzyme GGT degrades it. To the authors' knowledge, this is the first demonstration of the involvement of GGT-mediated GSH metabolism in the synthesis of colostrums, which elucidates the role of the enzyme that has always been reported very high in colostrum. © 2009 Blackwell Verlag GmbH
HyBIS: Windows Guest Protection through Advanced Memory Introspection
Effectively protecting the Windows OS is a challenging task, since most
implementation details are not publicly known. Windows has always been the main
target of malwares that have exploited numerous bugs and vulnerabilities.
Recent trusted boot and additional integrity checks have rendered the Windows
OS less vulnerable to kernel-level rootkits. Nevertheless, guest Windows
Virtual Machines are becoming an increasingly interesting attack target. In
this work we introduce and analyze a novel Hypervisor-Based Introspection
System (HyBIS) we developed for protecting Windows OSes from malware and
rootkits. The HyBIS architecture is motivated and detailed, while targeted
experimental results show its effectiveness. Comparison with related work
highlights main HyBIS advantages such as: effective semantic introspection,
support for 64-bit architectures and for latest Windows (8.x and 10), advanced
malware disabling capabilities. We believe the research effort reported here
will pave the way to further advances in the security of Windows OSes
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