561 research outputs found
Energy Conversion Using New Thermoelectric Generator
During recent years, microelectronics helped to develop complex and varied
technologies. It appears that many of these technologies can be applied
successfully to realize Seebeck micro generators: photolithography and
deposition methods allow to elaborate thin thermoelectric structures at the
micro-scale level. Our goal is to scavenge energy by developing a miniature
power source for operating electronic components. First Bi and Sb micro-devices
on silicon glass substrate have been manufactured with an area of 1cm2
including more than one hundred junctions. Each step of process fabrication has
been optimized: photolithography, deposition process, anneals conditions and
metallic connections. Different device structures have been realized with
different micro-line dimensions. Each devices performance will be reviewed and
discussed in function of their design structure.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Thermoelectric and microbattery hybrid system with its power management
Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/5920)International audienceIntegration of a power source with a MEMS to obtain an autonomous or remote system is a very challenging task. Such a device is currently being developed. It consists in hybriding an energy storage system (thin film solid state battery) with a scavenging energy system (thermogenerator) in a very small volume. It requires also power management to both control charge of the battery by the thermogenerator and discharge of the battery by the load, i.e. a sensor for instance
Controversies in Surgical Staging of Endometrial Cancer
Endometrial cancer is the most common gynaecological malignancy and its incidence is increasing. In 1998, international federation of gynaecologists and obstetricians (FIGO) required a change from clinical to surgical staging in endometrial cancer, introducing pelvic and paraaortic lymphadenectomy. This staging requirement raised controversies around the importance of determining nodal status and impact of lymphadenectomy on outcomes. There is agreement about the prognostic value of lymphadenectomy, but its extent, therapeutic value, and benefits in terms of survival are still matter of debate, especially in early stages. Accurate preoperative risk stratification can guide to the appropriate type of surgery by selecting patients who benefit of lymphadenectomy. However, available preoperative and intraoperative investigations are not highly accurate methods to detect lymph nodes and a complete surgical staging remains the most precise method to evaluate extrauterine spread of the disease. Laparotomy has always been considered the standard approach for endometrial cancer surgical staging. Traditional and robotic-assisted laparoscopic techniques seem to provide equivalent results in terms of disease-free survival and overall survival compared to laparotomy. These minimally invasive approaches demonstrated additional benefits as shorter hospital stay, less use of pain killers, lower rate of complications and improved quality of life
One-Step Laparoscopic Management of a Female Adnexal Tumor of Wolffian Origin
We report a case of female adnexal tumor of Wolffian origin (FATWO), a rare neoplasm arising from the mesonephric ducts. A 48-year-old woman came first to our center for a recent discovery of a pelvic mass. Transvaginal ultrasonographic findings suggested a solid right para-ovarian mass suspected to be malignant. After thorough counseling, the patient underwent operative laparoscopy for excision of the para-ovarian mass with frozen section (FS) examination resulting in the diagnosis of a poorly differentiated adenocarcinoma. In this case, FS results allowed performing a comprehensive oncological staging, through a totally laparoscopic extrafascial hysterectomy, bilateral adnexectomy, total omentectomy, pelvic wall peritonectomy, and pelvic, parasacral and para-aortic lymphadenectomy. Final pathological and immunohistochemical results confirmed the diagnosis of FATWO. To our knowledge, this is the first case of FATWO managed entirely by a minimally invasive laparoscopic approach in a single surgical session
On Flux Quantization in F-Theory II: Unitary and Symplectic Gauge Groups
We study the quantization of the M-theory G-flux on elliptically fibered
Calabi-Yau fourfolds with singularities giving rise to unitary and symplectic
gauge groups. We seek and find its relation to the Freed-Witten quantization of
worldvolume fluxes on 7-branes in type IIB orientifold compactifications on
Calabi-Yau threefolds. By explicitly constructing the appropriate four-cycles
on which to calculate the periods of the second Chern class of the fourfolds,
we find that there is a half-integral shift in the quantization of G-flux
whenever the corresponding dual 7-brane is wrapped on a non-spin submanifold.
This correspondence of quantizations holds for all unitary and symplectic gauge
groups, except for SU(3), which behaves mysteriously. We also perform our
analysis in the case where, in addition to the aforementioned gauge groups,
there is also a 'flavor' U(1)-gauge group.Comment: 33 pages, 4 figure
On Flux Quantization in F-Theory
We study the problem of four-form flux quantization in F-theory
compactifications. We prove that for smooth, elliptically fibered Calabi-Yau
fourfolds with a Weierstrass representation, the flux is always integrally
quantized. This implies that any possible half-integral quantization effects
must come from 7-branes, i.e. from singularities of the fourfold. We
subsequently analyze the quantization rule on explicit fourfolds with Sp(N)
singularities, and connect our findings via Sen's limit to IIB string theory.
Via direct computations we find that the four-form is half-integrally quantized
whenever the corresponding 7-brane stacks wrap non-spin complex surfaces, in
accordance with the perturbative Freed-Witten anomaly. Our calculations on the
fourfolds are done via toric techniques, whereas in IIB we rely on Sen's
tachyon condensation picture to treat bound states of branes. Finally, we give
general formulae for the curvature- and flux-induced D3 tadpoles for general
fourfolds with Sp(N) singularities.Comment: 46 page
Non-simply-laced Lie algebras via F theory strings
In order to describe the appearance in F theory of the non--simply--laced Lie
algebras, we use the representation of symmetry enhancements by means of string
junctions. After an introduction to the techniques used to describe symmetry
enhancement, that is algebraic geometry, BPS states analysis and string
junctions, we concentrate on the latter. We give an explicit description of the
folding of D_{2n} to B_n of the folding of E_6 to F_4 and that of D_4 to G_2 in
terms of junctions and Jordan strings. We also discuss the case of C_n, but we
are unable in this case to provide a string interpretation.Comment: 24 pages, 3 figure
Tate Form and Weak Coupling Limits in F-theory
We consider the weak coupling limit of F-theory in the presence of
non-Abelian gauge groups implemented using the traditional ansatz coming from
Tate's algorithm. We classify the types of singularities that could appear in
the weak coupling limit and explain their resolution. In particular, the weak
coupling limit of SU(n) gauge groups leads to an orientifold theory which
suffers from conifold singulaties that do not admit a crepant resolution
compatible with the orientifold involution. We present a simple resolution to
this problem by introducing a new weak coupling regime that admits
singularities compatible with both a crepant resolution and an orientifold
symmetry. We also comment on possible applications of the new limit to model
building. We finally discuss other unexpected phenomena as for example the
existence of several non-equivalent directions to flow from strong to weak
coupling leading to different gauge groups.Comment: 34 page
The new Checklist of the Italian Fauna: marine Mollusca.
The mollusc fauna of the Mediterranean Sea is still considered as the best-known marine mollusc fauna in the world. The previous modern checklists of marine Mollusca were produced by joint teams of amateurs and professionals. During the last years the Italian Society of Malacology (Società Italiana di Malacologia – S.I.M.) maintained an updated version of the Mediterranean checklist, that served as the backbone for the development of the new Italian checklist. According to the current version (updated on April 1st, 2021), 1,777 recognised species of marine molluscs are present in the Italian Economic Exclusive Zone, including also the Tyrrhenian coasts of Corsica and the continental shelf of the Maltese archipelago. The new checklist shows an increase of 17% of the species reported in the 1995 Checklist. This is largely (yet not solely) due to the new wave of studies based on Integrative Taxonomy approaches. A total of 135 species (7.6%) are strictly endemic to the Italian waters; 44 species (2.5%) are alien and correspond to the 28% of the Mediterranean alien marine molluscs. All eight extant molluscan classes are represented. The families represented in the Italian fauna are 307, an increase of 14.6% from the first checklist, partly due to new records and partly to new phylogenetic systematics. Compared with the whole Mediterranean malacofauna, the Italian component represents 71% in species and 61% in families, which makes it a very remarkable part of the Mediterranean fauna
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