42 research outputs found
Case of insulinoma detected in a patient after bariatric operation for morbid obesity
The prevalence of insulinomas is 1–3 cases per million population per year of which 4–14% tumor is malignant. Weight gain is one of the symptoms of the disease, often resulting in morbid obesity with indications for surgical treatment. The presented clinical case demonstrates the successful treatment of malignant insulinoma with the manifestation of hypoglycemic syndrome after carrying out biliopancreatic bypass with longitudinal gastrectomy for morbid obesity
Reconstructed historical distribution and phylogeography unravels non-steppic origin of Caucasotachea vindobonensis (Gastropoda: Helicidae)
Existing data on the phylogeography of European taxa of steppic provenance suggests that species were widely distributed during glacial periods but underwent range contraction and fragmentation during interglacials into “warm-stage refugia.” Among the steppe-related invertebrates that have been examined, the majority has been insects, but data on the phylogeography of snails is wholly missing. To begin to fill this gap, phylogeographic and niche modeling studies on the presumed steppic snail Caucasotachea vindobonensis were conducted. Surprisingly, reconstruction of ancestral areas suggests that extant C. vindobonensis probably originated in the Balkans and survived there during the Late Pleistocene glaciations, with a more recent colonization of the Carpatho-Pannonian and the Ponto-Caspian regions. In the Holocene, C. vindobonensis colonized between the Sudetes and the Carpathians to the north, where its recent and current distribution may have been facilitated by anthropogenic translocations. Together, these data suggest a possible non-steppic origin of C. vindobonensis. Further investigation may reveal the extent to which the steppic snail assemblages consist partly of Holocene newcomers
Wigner's Dynamical Transition State Theory in Phase Space: Classical and Quantum
A quantum version of transition state theory based on a quantum normal form
(QNF) expansion about a saddle-centre-...-centre equilibrium point is
presented. A general algorithm is provided which allows one to explictly
compute QNF to any desired order. This leads to an efficient procedure to
compute quantum reaction rates and the associated Gamov-Siegert resonances. In
the classical limit the QNF reduces to the classical normal form which leads to
the recently developed phase space realisation of Wigner's transition state
theory. It is shown that the phase space structures that govern the classical
reaction d ynamicsform a skeleton for the quantum scattering and resonance
wavefunctions which can also be computed from the QNF. Several examples are
worked out explicitly to illustrate the efficiency of the procedure presented.Comment: 132 pages, 31 figures, corrected version, Nonlinearity, 21 (2008)
R1-R11
Modeling of GERDA Phase II data
The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground
laboratory (LNGS) of INFN is searching for neutrinoless double-beta
() decay of Ge. The technological challenge of GERDA is
to operate in a "background-free" regime in the region of interest (ROI) after
analysis cuts for the full 100kgyr target exposure of the
experiment. A careful modeling and decomposition of the full-range energy
spectrum is essential to predict the shape and composition of events in the ROI
around for the search, to extract a precise
measurement of the half-life of the double-beta decay mode with neutrinos
() and in order to identify the location of residual
impurities. The latter will permit future experiments to build strategies in
order to further lower the background and achieve even better sensitivities. In
this article the background decomposition prior to analysis cuts is presented
for GERDA Phase II. The background model fit yields a flat spectrum in the ROI
with a background index (BI) of cts/(kgkeVyr) for the enriched BEGe data set and
cts/(kgkeVyr) for the
enriched coaxial data set. These values are similar to the one of Gerda Phase I
despite a much larger number of detectors and hence radioactive hardware
components
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Modeling of GERDA Phase II data
The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0νββ) decay of 76Ge. The technological challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg·yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Qββ for the 0νββ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2νββ) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of 16.04+0.78−0.85⋅10−3 cts/(keV·kg·yr) for the enriched BEGe data set and 14.68+0.47−0.52⋅10−3 cts/(keV·kg·yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components
Preventive medicine of von Hippel-Lindau disease-associated pancreatic neuroendocrine tumors
Pancreatic neuroendocrine tumors (PanNETs) are rare in von Hippel-Lindau disease (VHL) but cause serious morbidity and mortality. Management guidelines for VHL-PanNETs continue to be based on limited evidence, and survival data to guide surgical management are lacking. We established the European-American-Asian-VHL-PanNET-Registry to assess data for risks for metastases, survival and long-term outcomes to provide best management recommendations. Of 2330 VHL patients, 273 had a total of 484 PanNETs. Median age at diagnosis of PanNET was 35 years (range 10-75). Fifty-five (20%) patients had metastatic PanNETs. Metastatic PanNETs were significantly larger (median size 5 vs 2\u2009cm; P\u20091.5\u2009cm in diameter were operated. Ten-year survival was significantly longer in operated vs non-operated patients, in particular for PanNETs <2.8\u2009cm vs 652.8\u2009cm (94% vs 85% by 10 years; P\u2009=\u20090.020; 80% vs 50% at 10 years; P\u2009=\u20090.030). This study demonstrates that patients with PanNET approaching the cut-off diameter of 2.8\u2009cm should be operated. Mutations in exon 3, especially of codons 161/167 are at enhanced risk for metastatic PanNETs. Survival is significantly longer in operated non-metastatic VHL-PanNETs
High resolution measurement of telecommunication component polarization mode dispersion by means of quantum interferometry
Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.As optical transport networks migrate towards supporting optical channel (or superchannel) bitrates of 100Gbps, 400Gbps, or even 1 Tbps, it becomes more important to conduct careful analysis, precise characterization, and optimized mitigation of polarization mode dispersion (PMD) in order to deliver optimal performance in fiber-optic communication systems. Telecommunication service providers need their system vendors to match the performance of their platforms to the overall system PMD accumulation, including both fiber and component PMD. The fiber PMD is a characteristic of the optical fiber plant and is very heterogeneous in both its design and time of installation. Today all installed fiber plants require mitigation solutions for PMD-induced impairments when transporting optical channels with bitrates of 40Gbps and higher.
The component PMD is due to discrete components present in the optical path of a lightwave channel, such as Wavelength Selective Switches (WSS), amplifiers, Dispersion Compensating Modules (DCM), and multiplexer/demultiplexer structures. The proliferation of components, especially WSSs, has rapidly accelerated recently with the introduction of Reconfigurable Optical Add Drop Multiplexers (ROADM). Each component contributes a relatively small value to the overall system PMD. Until recently, these components were not considered to be important contributors to the total. The significance of component PMD suddenly became very apparent because ROADM introduction into the fiber-optic network fabric increased the number of components at least ten-fold. Depending on the Link Design Value (LDV) of network fabric, the component PMD can now contribute an amount similar to or even greater than the PMD penalty incurred in the fiber.
Today's state of the art tedmiques in PMD measurement focus solely on characterizing fiber PMD. In our research we have developed a new method to measure very small values of PMD (or Differential Group Delay (DOD)) in discrete components of optical fiber communication systems based on the utilization of quantum interferometry. We designed a polarization counterpart of the Hong-Ou-Mandel (HOM) interferometer with entangled photons operating in the telecommunication region of the optical spectrum. Using this setup we were able to demonstrate close to 1 fs resolution while measuring DGD values of a 1x9 port Wavelength Selective Switch (WSS), based on Micro Electro Mechanical System (MEMS). We used a specially designed source of broadband polarization entangled photon pairs generated in the process of collinear type-II Spontaneous Parametric Down Conversion (SPDC). Our result paves the way for building future test and measurement devices that will be capable of resolving even smaller PMD values in discrete components of future optical communication systems, ultimately with atto-second resolution.2031-01-0