1,305 research outputs found
Mapping deuterated methanol toward L1544: I. Deuterium fraction and comparison with modeling
The study of deuteration in pre-stellar cores is important to understand the
physical and chemical initial conditions in the process of star formation. In
particular, observations toward pre-stellar cores of methanol and deuterated
methanol, solely formed on the surface of dust grains, may provide useful
insights on surface processes at low temperatures. Here we analyze maps of CO,
methanol, formaldehyde and their deuterated isotopologues toward a well-known
pre-stellar core. This study allows us to test current gas-dust chemical
models. Single-dish observations of CHOH, CHDOH, HCO,
H_2\,^{13}CO, HDCO, DCO and CO toward the prototypical pre-stellar
core L1544 were performed at the IRAM 30 m telescope. We analyze their column
densities, distributions, and compare these observations with gas-grain
chemical models. The maximum deuterium fraction derived for methanol is
[CHDOH]/[CHOH] 0.080.02, while the measured deuterium
fractions of formaldehyde at the dust peak are [HDCO]/[HCO]
0.030.02, [DCO]/[HCO] 0.040.03 and [DCO]/[HDCO]
1.20.3. Observations differ significantly from the predictions of
models, finding discrepancies between a factor of 10 and a factor of 100 in
most cases. It is clear though that to efficiently produce methanol on the
surface of dust grains, quantum tunneling diffusion of H atoms must be switched
on. It also appears that the currently adopted reactive desorption efficiency
of methanol is overestimated and/or that abstraction reactions play an
important role. More laboratory work is needed to shed light on the chemistry
of methanol, an important precursor of complex organic molecules in space.Comment: Accepted for publication in A&
A REST-based framework to support non-invasive and early coeliac disease diagnosis
The health sector has traditionally been one of the early adopters of databases, from the most simple Electronic Health Record (formerly Computer-Based Patient Record) systems in use in general practice, hospitals and intensive care units to big data, multidata based systems used to support diagnosis and care decisions. In this paper we present a framework to support non-invasive and early diagnosis of coeliac disease. The proposed framework makes use of well-known technologies and techniques, both hardware and software, put together in a novel way. The main goals of our framework are: (1) providing users with a reliable and fast repository of a large amount of data; (2) to make such repository accessible by means of a suitable API in multiple modes, such as intuitive web-based or mobile visual interfaces; (3) to allow for data processing and analysis, as a basis for decision support systems
Quantum Poincare Recurrences for Hydrogen Atom in a Microwave Field
We study the time dependence of the ionization probability of Rydberg atoms
driven by a microwave field, both in classical and in quantum mechanics. The
quantum survival probability follows the classical one up to the Heisenberg
time and then decays algebraically as P(t) ~ 1/t. This decay law derives from
the exponentially long times required to escape from some region of the phase
space, due to tunneling and localization effects. We also provide parameter
values which should allow to observe such decay in laboratory experiments.Comment: revtex, 4 pages, 4 figure
Spinal vascular lesions: anatomy, imaging techniques and treatment
Vascular lesions of the spinal cord are rare but potentially devastating conditions whose accurate recognition critically determines the clinical outcome. Several conditions lead to myelopathy due to either arterial ischemia, venous congestion or bleeding within the cord. The clinical presentation varies, according with the different aetiology and mechanism of damage
Hundred photon microwave ionization of Rydberg atoms in a static electric field
We present analytical and numerical results for the microwave excitation of
nonhydrogenic atoms in a static electric field when up to 1000 photons are
required to ionize an atom. For small microwave fields, dynamical localization
in photon number leads to exponentially small ionization while above quantum
delocalization border ionization goes in a diffusive way. For alkali atoms in a
static field the ionization border is much lower than in hydrogen due to
internal chaos.Comment: revtex, 4 pages, 5 figure
Systemic treatment of malignant gastrointestinal neuroectodermal tumour after childhood neuroblastoma: chemotherapy in malignant gastrointestinal neuroectodermal tumour
Malignant gastrointestinal neuroectodermal tumour is an extremely rare neoplasm that arises in the wall
of the small bowel, stomach or large bowel in youngaged and middle-aged adults. Histologically, it is
generally characterized by monomorphic cells with clear cytoplasma, S-100 protein expression, and EWSR1 gene
translocation. To the best of our knowledge, we describe for the first time, the case of a young woman with a diagnosis of metastatic gastrointestinal neuroectodermal tumour arising from ileum, who had a childhood adrenal
neuroblastoma with liver, bone and lymph nodes metastasis, treated with four cycles of chemotherapy
with the schedule CADO-CVP (CADO: cyclophosphamide 300 mg/m2/day on days 1–5, vincristine 1,5 mg/m2/ day on days 1 and 5, and doxorubicin 60 mg/m2/day on day 5; CVP: cisplatin 40 mg/m2/day on days 1–5 and etoposide 100 mg/m2/day on days 1–5) followed by right adrenal, kidney, lymph nodes and liver lesion resection, conditioning chemotherapy (melphalan-carmustineteniposide), stem cells autologous transplantation and consecutively radiotherapy on the spine (T9 to L3) for a total of 30 Gy. For the second diagnosis of gastrointestinal neuroectodermal tumour with liver metastasis, she underwent ileal tumour resection and platinum-anthracycline based chemotherapy with initial shrinkage of liver metastasis. Unfortunately, despite the initial response and the following delivered therapies, she died for rapid progressive disease. Taking into account the late effects of past therapeutic modalities, a long-term surveillance of young child treated for neuroblastoma, is required to appreciate their overall risks of second malignancies
Efficient Quantum Computing of Complex Dynamics
We propose a quantum algorithm which uses the number of qubits in an optimal
way and efficiently simulates a physical model with rich and complex dynamics
described by the quantum sawtooth map. The numerical study of the effect of
static imperfections in the quantum computer hardware shows that the main
elements of the phase space structures are accurately reproduced up to a time
scale which is polynomial in the number of qubits. The errors generated by
these imperfections are more dangerous than the errors of random noise in gate
operations.Comment: revtex, 4 pages, 3 figure
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