252 research outputs found
Unbiased estimation of an optical loss at the ultimate quantum limit with twin-beams
Loss measurements are at the base of spectroscopy and imaging, thus perme-
ating all the branches of science, from chemistry and biology to physics and
material science. However, quantum mechanics laws set the ultimate limit to the
sensitivity, constrained by the probe mean energy. This can be the main source
of uncertainty, for example when dealing with delicate system such as
biological samples or photosensitive chemicals. It turns out that ordinary
(clas- sical) probe beams, namely with Poissonian photon number distribution,
are fundamentally inadequate to measure small losses with the highest
sensitivity. Conversely, we demonstrate that a quantum-correlated pair of
beams, known as twin-beam state, allows reaching the ultimate sensitivity for
all energy regimes (even less than one photon per mode) with the simplest
measurement strategy. One beam of the pair addresses the sample, while the
second one is used as a reference to compensate both for classical drifts and
for uctuation at the most fundamental quantum level. This scheme is also
absolute and accurate, since it self-compensates for unavoidable instability of
the sources and detectors, which could otherwise lead to strongly biased
results. Moreover, we report the best sensitivity per photon ever achieved in
loss estimation experiments
Quantum differential ghost microscopy
Quantum correlations become formidable tools for beating classical capacities
of measurement. Preserving these advantages in practical systems, where
experimental imperfections are unavoidable, is a challenge of the utmost
importance. Here we propose and realize a quantum ghost imaging protocol able
to compensate for the detrimental effect of detection noise and losses. This
represents an important improvement as quantum correlations allow low
brightness imaging, desirable for reducing the absorption dose. In particular,
we develop a comprehensive model starting from a ghost imaging scheme
elaborated for bright thermal light, known as differential ghost imaging and
particularly suitable in the relevant case of faint or sparse objects. We
perform the experiment using SPDC light in microscopic configuration. The image
is reconstructed exploiting non-classical intensity correlation rather than
photon pairs detection coincidences. On one side we validate the theoretical
model and on the other we show the applicability of this technique by
reconstructing a biological object with 5 micrometers resolution
Photon number correlation for quantum enhanced imaging and sensing
In this review we present the potentialities and the achievements of the use
of non-classical photon number correlations in twin beams (TWB) states for many
applications, ranging from imaging to metrology. Photon number correlations in
the quantum regime are easy to be produced and are rather robust against
unavoidable experimental losses, and noise in some cases, if compared to the
entanglement, where loosing one photon can completely compromise the state and
its exploitable advantage. Here, we will focus on quantum enhanced protocols in
which only phase-insensitive intensity measurements (photon number counting)
are performed, which allow probing transmission/absorption properties of a
system, leading for example to innovative target detection schemes in a strong
background. In this framework, one of the advantages is that the sources
experimentally available emit a wide number of pairwise correlated modes, which
can be intercepted and exploited separately, for example by many pixels of a
camera, providing a parallelism, essential in several applications, like wide
field sub-shot-noise imaging and quantum enhanced ghost imaging. Finally,
non-classical correlation enables new possibilities in quantum radiometry, e.g.
the possibility of absolute calibration of a spatial resolving detector from
the on-off- single photon regime to the linear regime, in the same setup
Development of films from polypropylene/talc nanocomposites for aroma retention
Se estudia la liberación de aceite esencial de limón (aroma modelo) en películas sopladas de nanocompuestos a base de polipropileno (PP) conteniendo 5% p/p de partículas de talco. En tal sentido, se utilizaron tres técnicas independientes y complementarias para estudiar dicho fenómeno físico, tales como: gravimetría, termogravimetría y espectroscopía infrarroja con transformada de Fourier. Los resultados obtenidos demostraron que las películas de nanocompuestos liberaron el aceite esencial de manera más lenta y prolongada en comparación con las del PP. Las partículas de talco actuaron como "retén" del aceite esencial por su carácter absorbente. Además, obstaculizaron el pasaje de las moléculas aromáticas a través de la película por la disposición espacial que alcanzan en la matriz polimérica y por el incremento del grado de cristalinidad que inducen en el PP, debido al carácter nucleante de estas partículas.The release of lemon oil (flavor model) in nanocomposites blown films based on polypropylene (PP) containing 5% w/w of talc particles is studied. In this sense, three independent and complementary techniques were used to study this physical phenomenon, such as: gravimetry, thermogravimetry and infrared spectroscopy with Fourier transform. The results showed that the nanocomposite films released essential oil slower and prolonged compared to PP ones. Talc particles acted as "retention agents" of essential oil because of their absorbent character. Also, they hindered aromatic molecules passage through the film reaching the spatial arrangement in the polymer matrix and the increment in crystallinity degree induced in PP by the nucleating character of these particles.Fil: Genovese, Constanza. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Alonso, Yanela Natalin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Castillo, Luciana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Barbosa, Silvia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin
Erroneous intra-articular injection of gadolinium solution at 0.5 mol/l concentration: a case report
Magnetic Resonance arthrography is considered the gold standard imaging technique for the study of shoulder instability and tendon tears
Quantum Conformance Test
We introduce a protocol addressing the conformance test problem, which
consists in determining whether a process under test conforms to a reference
one. We consider a process to be characterized by the set of end-product it
produces, which is generated according to a given probability distribution. We
formulate the problem in the context of hypothesis testing and consider the
specific case in which the objects can be modeled as pure loss channels. We
demonstrate theoretically that a simple quantum strategy, using readily
available resources and measurement schemes in the form of two-mode squeezed
vacuum and photon-counting, can outperform any classical strategy. We
experimentally implement this protocol, exploiting optical twin beams,
validating our theoretical results, and demonstrating that, in this task, there
is a quantum advantage in a realistic setting
INITIAL IMPACT OF THE COVID-19 PANDEMIC ON THE CARE PROFILE FOR CRITICALLY-ILL PATIENTS ON HEMODIALYSIS
Objective: to compare the care profile for critically-ill patients on hemodialysis before and during the COVID-19 pandemic.Method: an observational study carried out in a hospital from São Paulo, Brazil. The participants were critically-ill patients on hemodialysis hospitalized in 2019 and 2020. The data were collected from documents of hemodialysis sessions and from medical records. Chi-square, Mann-Whitney, Shapiro-Wilk and Fisher's Exact tests were used for comparisons (p<0.05).Results: a total of 212 sessions were performed with 50 patients in 2019 and 873 sessions with 171 patients in 2020. In 2019, the patients were referred to intensive care and hemodialysis after 4.62 ± 6.38 and 17.26 ± 24.53 days, respectively, and in 2020 these periods corresponded to 2.21 ± 3.63 and 10.24 ± 11.99 days. There were more deaths in 2020 (p=0.01) and among patients with COVID-19 (p=0.014).Conclusion: more hemodialysis sessions were observed in 2020 when compared to pre-pandemic times, an unknown situation in the first months of the pandemic
Phleboviruses detection in Phlebotomus perniciosus from a human leishmaniasis focus in South-West Madrid region, Spain
Phlebotomus-borne (PhB-) viruses are distributed in large areas of the Old World and are widespread throughout the Mediterranean basin, where recent investigations have indicated that virus diversity is higher than initially suspected. Some of these viruses are causes of meningitis, encephalitis and febrile illnesses. In order to monitor the viral presence and the infection rate of PhB-viruses in a recently identified and well characterized human zoonotic leishmaniasis focus in southwestern Madrid, Spain, a sand fly collection was carried out.
Methods
Sand fly insects were collected in four stations using CDC light traps during 2012–2013 summer seasons. Screening for Phlebovirus presence both via isolation on Vero cells and via polymerase chain reaction (PCR), using degenerated primers targeting a portion of the L segment, was performed. The serological identity and phylogenetic relationships on the three genomic segments of the viral isolates were carried out.
Results
Six viral isolates belonging to different serological complexes of the genus Phlebovirus were obtained from fifty pools on a total of 963 P. perniciosus (202 females). Phylogenetic analysis and serological assays allowed the identification of two isolates of Toscana virus (TOSV) B genotype, three isolates strongly related to Italian Arbia virus (ARBV), and one isolate of a novel putative Phlebovirus related to the recently characterized Arrabida virus in South Portugal, tentatively named Arrabida-like virus. Positive male sand fly pools suggested that transovarial or venereal transmission could occur under natural conditions.
Conclusions
Our findings highlighted the presence of different Phlebovirus species in the South-West area of the Madrid Autonomous Community where an outbreak of cutaneous and visceral human leishmaniasis has been recently described. The evidence of viral species never identified before in Spain, as ARBV and Arrabida-like virus, and TOSV B genotype focus stability was demonstrated. Environmental aspects such as climate change, growing urbanization, socio-economic development could have contributed to the genesis of this wide ecological niche of PhB-viruses and Leishmania spp. The potential role of vertebrates as reservoir for the phleboviruses identified and the possibility of Phleboviruses-Leishmania co-infection in the same sand fly should be assessed. Furthermore the PhB-viruses impact on human health should be implemented.This study was funded by EU grant FP7-261504 EDENext and is catalogued
by the EDENext Steering Committee as EDENext432 (http://www.edenext.eu).
The contents of this publication are the sole responsibility of the authors
and do not necessarily reflect the views of the European Commission.S
Experimental quantum reading with photon counting
The final goal of quantum hypothesis testing is to achieve quantum advantage over all possible classical strategies. In the protocol of quantum reading this advantage is achieved for information retrieval from an optical memory, whose generic cell stores a bit of information in two possible lossy channels. For this protocol, we show, theoretically and experimentally, that quantum advantage is obtained by practical photon-counting measurements combined with a simple maximum-likelihood decision. In particular, we show that this receiver combined with an entangled two-mode squeezed vacuum source is able to outperform any strategy based on statistical mixtures of coherent states for the same mean number of input photons. Our experimental findings demonstrate that quantum entanglement and simple optics are able to enhance the readout of digital data, paving the way to real applications of quantum reading and with potential applications for any other model that is based on the binary discrimination of bosonic loss
Circulating MicroRNA-15a Associates With Retinal Damage in Patients With Early Stage Type 2 Diabetes
: Circulating microRNAs are potential biomarkers of type 2 diabetes mellitus (T2DM) and related complications. Here, we investigated the association of microRNA-15a with early retinal damage in T2DM. A cohort of untreated subjects screened for intermediate/high risk of T2DM, according to a score assessment questionnaire, and then recognized to have a normal (NGT) or impaired (IGT) glucose tolerance or T2DM was studied. The thickness of the ganglion cell complex (GCC), an early marker of retinal degeneration anteceding overt retinopathy was assessed by Optical Coherence Tomography. Total and extracellular vesicles (EV)-associated microRNA-15a quantity was measured in plasma by real time PCR. MicroRNA-15a level was significantly higher in subjects with IGT and T2DM compared with NGT. MicroRNA-15a abundance was correlated to body mass index and classical diabetes biomarkers, including fasting glucose, HbA1c, insulinemia, and HOMA-IR. Moreover, GCC thickness was significantly reduced in IGT and T2DM subjects compared with NGT controls. Importantly, total microRNA-15a correlated with GCC in IGT subjects, while in T2DM subjects, EV-microRNA-15a negatively correlated with GCC, suggesting that microRNA-15a may monitor initial retinal damage. The assessment of plasma microRNA-15a may help refining risk assessment and secondary prevention in patients with preclinical T2DM
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