Timing resistive plate chambers for thermal neutron detection with 3D position sensitivity

An optimized design of a neutron detector based on timing RPCs (Resistive Plate Chambers) with boron-10 neutron converters is presented. The detector is composed of a stack of ten double gap RPCs with aluminium cathode plates coated on both sides with $^{10}B_{4}C$. This design enables simultaneous determination with high accuracy of both the neutron time-of-flight (down to ns resolution) and the interaction position in 3D (down to 0.25 mm resolution across and ~1 mm along the beam). It is shown that the detection efficiency can approach 60% for neutrons with $\lambda$ = 4.7 \.A. A new geometry with less material budget is introduced for the signal pick-up strip arrays. The results of simulation-based optimization of the design are reported considering the trade-off between the detection efficiency, the count rate capability and the amount of elastic scattering on the detector components

Pré-termos abaixo das 27 semanas de idade gestacional: desfechos num hospital terciário.

Introduction: Over the last decades, survival of extremely preterm infants improved but there´s still significant morbidity among this group. We pretend to evaluate if specific attitudes/characteristics are associated with higher survival or survival without severe disabilities and elaborate predicting outcome models. Material and Methods: Observational descriptive study, including the 205 liveborn/stillborn infants -gestational age 22w0d-26w6d- born at an Obstetrics Unit or transferred to a Neonatology Unit of a Level III Hospital, from January-2000 to December-2009. We collected variables related to management in the prenatal/neonatal period, neonate performances and psychomotor development (18-24 months). Significant associations between variables/outcomes were identified by chi-square test or t-test; multivariate logistic regression models were used to describe and predict mortality/morbidity. Results: Advanced Gestational Age (GA) (p=0.001), antenatal corticotherapy(p=0.001), cesarean section(p=0.001), inborn delivery(p=0.021) and increased weight(p=0.001) were associated with survival. Absence of Intraventricular Hemorrhage (IVH) grade 3-4(p=0.001) and absence of Periventricular Leukomalacia (PVL) (p=0.005) were associated with survival without severe neurossensorial deficit. According to multivariable models, advanced GA (OR=0.353,CI95% 0.208-0.599), increased weight (OR=0.996,CI95% 0.993-0.999) and antenatal corticotherapy (OR=0.150,CI95% 0.044-0.510) were associated with lower mortality risk. Rupture of membranes less than 12 h duration was associated with higher mortality risk (OR=3.88,CI95% 1.406-10.680). IVH grades 3-4 was associated with higher morbidity risk (OR=16.931,CI95% 2.744-104.452). Mortality and severe morbidity models predicted correctly the outcome in 78.1% and 85.7% of the cases, respectively. Conclusions: Mortality/morbidity models might be valuable tools providing insight in the prediction of the outcome of these neonates and helping parental counseling

Hipervitaminosis D with Hypocalcemic Coma

A intoxicação pela vitamina D é uma causa bem conhecida de hipercalcémia e hiperfosfatemia. Nos casos de intoxicação crónica, quando o produto fosfocálcico é superior a 60 mg2/dl2, verifica-se a deposição de cristais de fosfato de cálcio, nos tecidos moles, com subsequente hipocalcémia. Apresenta-se o caso de uma lactente de três meses de idade, com antecedentes pessoais irrelevantes, internada na Unidade de Cuidados Intensivos Pediátricos, por tetania e coma resultante da intoxicação crónica acidental pela vitamina D, desde os dez dias de vida. Apresentava hipocalcémia (cálcio total 4,44mg/dl e cálcio ionizado 0,45 mg/dl) e hiper-fosfatémia (fósforo 17,8 mg/dl) grave, sendo o produto fosfocálcico de 79 mg2/dl2. A intoxicação pela vitamina D e hipocalcémia paradoxal foi confirmada pelo doseamento de 1,25-vitamina D

Spectrophotometric properties of dwarf planet Ceres from the VIR spectrometer on board the Dawn mission

We study the spectrophotometric properties of dwarf planet Ceres in the VIS-IR spectral range by means of hyper-spectral images acquired by the VIR imaging spectrometer on board the NASA Dawn mission. Disk-resolved observations with a phase angle within the $7^{\circ}<\alpha<132^{\circ}$ interval were used to characterize Ceres' phase curve in the 0.465-4.05 $\mu$m spectral range. Hapke's model was applied to perform the photometric correction of the dataset, allowing us to produce albedo and color maps of the surface. The $V$-band magnitude phase function of Ceres was fitted with both the classical linear model and H-G formalism. The single-scattering albedo and the asymmetry parameter at 0.55$\mu$m are $w=0.14\pm0.02$ and $\xi=-0.11\pm0.08$, respectively (two-lobe Henyey-Greenstein phase function); the modeled geometric albedo is $0.094\pm0.007$; the roughness parameter is $\bar{\theta}=29^{\circ}\pm6^{\circ}$. Albedo maps indicate small variability on a global scale with an average reflectance of $0.034 \pm 0.003$. Isolated areas such as the Occator bright spots, Haulani, and Oxo show an albedo much higher than average. We measure a significant spectral phase reddening, and the average spectral slope of Ceres' surface after photometric correction is $1.1\%k\AA^{-1}$ and $0.85\%k\AA^{-1}$ at VIS and IR wavelengths, respectively. Broadband color indices are $V-R=0.38\pm0.01$ and $R-I=0.33\pm0.02$. H-G modeling of the $V$-band magnitude phase curve for $\alpha<30^{\circ}$ gives $H=3.14\pm0.04$ and $G=0.10\pm0.04$, while the classical linear model provides $V(1,1,0^{\circ})=3.48\pm0.03$ and $\beta=0.036\pm0.002$. The comparison with spectrophotometric properties of other minor bodies indicates that Ceres has a less back-scattering phase function and a slightly higher albedo than comets and C-type objects. However, the latter represents the closest match in the usual asteroid taxonomy.Comment: 14 pages, 20 figures, published online on Astronomy and Astrophysics on 13 February 2017. Revised to reflect minor changes in text and figures made in proofs, updated value of V-R and R-

A new high-resolution TOF technology

In the framework of the ALICE collaboration we have recently studied the performance of multigap Resistive Plate Chambers operated in avalanche mode and at atmospheric pressure for time-of-flight measurements. The detector provided an overall (detector plus electronics) timing accuracy of 120 ps sigma at an efficiency of 98% for MIPs. The chambers had 4 gas gaps of 0.3 mm, each limited by a metallised ceramic plate and a glass plate, with an active dimension of 4'4cm2. The gas mixture contained C2H2F4+5%isobutane+10%SF6. A few percent of streamer discharges, each releasing about 20 pC, was tolerated without any noticeable inconvenience. This detector opens perspectives of affordable and reliable high granularity large area TOF detectors, with an efficiency and a time resolution comparable to existing scintillator-based TOF technology but with significantly, up to an order of magnitude, lower price per channel

The ground state of the carbon atom in strong magnetic fields

The ground and a few excited states of the carbon atom in external uniform magnetic fields are calculated by means of our 2D mesh Hartree-Fock method for field strengths ranging from zero up to 2.35 10^9 T. With increasing field strength the ground state undergoes six transitions involving seven different electronic configurations which belong to three groups with different spin projections S_z=-1,-2,-3. For weak fields the ground state configuration arises from the field-free 1s^2 2s^2 2p_0 2p_{-1}, S_z=-1 configuration. With increasing field strength the ground state involves the four S_z=-2 configurations 1s^22s2p_0 2p_{-1}2p_{+1}, 1s^22s2p_0 2p_{-1}3d_{-2}, 1s^22p_0 2p_{-1}3d_{-2}4f_{-3} and 1s^22p_{-1}3d_{-2}4f_{-3}5g_{-4}, followed by the two fully spin polarized S_z=-3 configurations 1s2p_02p_{-1}3d_{-2}4f_{-3}5g_{-4} and 1s2p_{-1}3d_{-2}4f_{-3}5g_{-4}6h_{-5}. The last configuration forms the ground state of the carbon atom in the high field regime \gamma>18.664. The above series of ground state configurations is extracted from the results of numerical calculations for more than twenty electronic configurations selected due to some general energetical arguments.Comment: 6 figures,acc. Phys.Rev.

The next challenge for world wide robotized tele-echography experiment (WORTEX 2012): from engineering success to healthcare delivery.

Access to good quality healthcare remains difficult for many patients whether they live in developed or developing countries. In developed countries, specialist medical expertise is concentrated in major hospitals in urban settings both to improve clinical outcomes and as a strategy to reduce the costs of specialist healthcare delivery. In developing countries, millions of people have limited, if any, routine access to a healthcare system and due to economic and cultural factors the accessibility of any services may be restricted. In both cases, geographical, socio-political, cultural and economic factors produce ‘medically isolated areas’ where patients find themselves disadvantaged in terms of timely diagnosis and expert and/or expensive treatment. The robotized teleechography approach, also referred to as robotized teleultrasound, offers a potential solution to diagnostic imaging in medically isolated areas. It is designed for patients requiring ultrasound scans for routine care (e.g., ante natal care) and for diagnostic imaging to investigate acute and medical emergencies conditions, including trauma care and responses to natural disasters such as earthquakes. The robotized teleechography system can hold any standard ultrasound probe; this lightweight system is positioned on the patient’s body by a healthcare assistant. The medical expert, a clinician with expertise in ultrasound imaging and diagnosis, is in a distant location and, using a dedicated joystick, remotely controls the scanning via any available communication link (Internet, satellite). The WORTEX2012 intercontinental trials of the system conducted last year successfully demonstrated the feasibility of remote robotized tele-echography in a range of cultural, technical and clinical contexts. In addition to the engineering success, these trials provided positive feedback from the participating clinicians and patients on using the system and on the system’s perceived potential to transform healthcare in medically isolated areas. The next challenge is to show evidence that this innovative technology can deliver on its promise if introduced into routine healthcare