2,255 research outputs found
Optimizing electrode implantation in sacral nerve stimulation—an anatomical cadaver study controlled by a laparoscopic camera
Background and aim: Sacral nerve stimulation is the therapy of choice in patients with neurogenic faecal and urine incontinence, constipation and some pelvic pain syndromes. The aim of this study is to determine the best insertion angles of the electrode under laparoscopic visualization of the sacral nerves. Materials and methods: Five fresh cadaver pelvises were dissected through an anterior approach of the presacral space, exposing the ventral sacral roots. Needles and electrodes were inserted into the S3 foramen. Both right and left sides were used, with the traditional percutaneous procedure. The validation was done by a laparoscopic camera controlling the position of the needle and electrode on the nerve. The angles were assessed with a goniometer and were confirmed in two living patients. Results: The mean angle of insertion in the sagittal plane was 62.9 ± 3° (range, 59-70). In the axial plane, the mean angle for the left side was 91.7 ± 13.5° (range, 80-110) and 83.2 ± 7.7° for the right side (range, 75-95). These angles resulted in the optimal placement of the leads along the S3 sacral root, in all these cases. Conclusions: This study allows direct visualization during the placement of the needle and electrode, thus permitting accurate calculations of the best angle of approach during the surgical procedure in sacral nerve stimulation. These objective findings attempt to standardize this technique, which is often performed with the aid of intra-operative fluoroscopy but still leaving a lot to chance. These insertion angles should help to find more consistent and reproducible results and thus improved outcome in patient
An explicit KO-degree map and applications
The goal of this note is to study the analog in unstable -homotopy theory of the unit map from the motivic sphere spectrum to the
Hermitian K-theory spectrum, i.e., the degree map in Hermitian K-theory. We
show that "Suslin matrices", which are explicit maps from odd dimensional split
smooth affine quadrics to geometric models of the spaces appearing in Bott
periodicity in Hermitian K-theory, stabilize in a suitable sense to the unit
map. As applications, we deduce that for ,
which can be thought of as an extension of Matsumoto's celebrated theorem
describing of a field. These results provide the first step in a program
aimed at computing the sheaf for .Comment: 36 Pages, Final version, to appear Journal of Topolog
Theoretical analysis of the electronic structure of the stable and metastable c(2x2) phases of Na on Al(001): Comparison with angle-resolved ultra-violet photoemission spectra
Using Kohn-Sham wave functions and their energy levels obtained by
density-functional-theory total-energy calculations, the electronic structure
of the two c(2x2) phases of Na on Al(001) are analysed; namely, the metastable
hollow-site structure formed when adsorption takes place at low temperature,
and the stable substitutional structure appearing when the substrate is heated
thereafter above ca. 180K or when adsorption takes place at room temperature
from the beginning. The experimentally obtained two-dimensional band structures
of the surface states or resonances are well reproduced by the calculations.
With the help of charge density maps it is found that in both phases, two
pronounced bands appear as the result of a characteristic coupling between the
valence-state band of a free c(2x2)-Na monolayer and the
surface-state/resonance band of the Al surfaces; that is, the clean (001)
surface for the metastable phase and the unstable, reconstructed "vacancy"
structure for the stable phase. The higher-lying band, being Na-derived,
remains metallic for the unstable phase, whereas it lies completely above the
Fermi level for the stable phase, leading to the formation of a
surface-state/resonance band-structure resembling the bulk band-structure of an
ionic crystal.Comment: 11 pages, 11 postscript figures, published in Phys. Rev. B 57, 15251
(1998). Other related publications can be found at
http://www.rz-berlin.mpg.de/th/paper.htm
Latrocimicinae completes the phylogeny of Cimicidae: meeting old morphologic data rather than modern host phylogeny.
The family Cimicidae includes obligate hematophagous ectoparasites (bed bugs and their relatives) with high veterinary/medical importance. The evolutionary relationships of Cimicidae and their hosts have recently been reported in a phylogenetic context, but in the relevant study, one of the six subfamilies, the bat-specific Latrocimicinae, was not represented. In this study the only known species of Latrocimicinae, i.e., Latrocimex spectans, was analyzed with molecular and phylogenetic methods based on four (two nuclear and two mitochondrial) genetic markers. The completed subfamily-level phylogeny of Cimicidae showed that Latrocimicinae is most closely related to Haematosiphoninae (ectoparasites of birds and humans), with which it shares systematically important morphologic characters, but not hosts. Moreover, in the phylogenetic analyses, cimicid bugs that are known to infest phylogenetically distant bat hosts clustered together (e.g., Leptocimex and Stricticimex within Cacodminae), while cimicid subfamilies (Latrocimicinae, Primicimicinae) that are known to infest bat hosts from closely related superfamilies clustered distantly. In conclusion, adding Latrocimicinae significantly contributed to the resolution of the phylogeny of Cimicidae. The close phylogenetic relationship between Latrocimicinae and Haematosiphoninae is consistent with long-known morphologic data. At the same time, phylogenetic relationships of genera within subfamilies are inconsistent with the phylogeny of relevant hosts
High coherence photon pair source for quantum communication
This paper reports a novel single mode source of narrow-band entangled photon
pairs at telecom wavelengths under continuous wave excitation, based on
parametric down conversion. For only 7 mW of pump power it has a created
spectral radiance of 0.08 pairs per coherence length and a bandwidth of 10 pm
(1.2 GHz). The effectively emitted spectral brightness reaches 3.9*10^5 pairs
/(s pm). Furthermore, when combined with low jitter single photon detectors,
such sources allow for the implementation of quantum communication protocols
without any active synchronization or path length stabilization. A HOM-Dip with
photons from two autonomous CW sources has been realized demonstrating the
setup's stability and performance.Comment: 12 pages, 4 figure
Fullerene-based molecular nanobridges: A first-principles study
Building upon traditional quantum chemistry calculations, we have implemented
an {\em ab-initio} method to study the electrical transport in nanocontacts. We
illustrate our technique calculating the conductance of C molecules
connected in various ways to Al electrodes characterized at the atomic level.
Central to a correct estimate of the electrical current is a precise knowledge
of the local charge transfer between molecule and metal which, in turn,
guarantees the correct positioning of the Fermi level with respect to the
molecular orbitals. Contrary to our expectations, ballistic transport seems to
occur in this system.Comment: 4 pages in two-column forma
A bank of unscented Kalman filters for multimodal human perception with mobile service robots
A new generation of mobile service robots could be ready soon to operate in human environments if they can robustly estimate position and identity of surrounding people. Researchers in this field face a number of challenging problems, among which sensor uncertainties and real-time constraints.
In this paper, we propose a novel and efficient solution for simultaneous tracking and recognition of people within the observation range of a mobile robot. Multisensor techniques for legs and face detection are fused in a robust probabilistic framework to height, clothes and face recognition algorithms. The system is based on an efficient bank of Unscented Kalman Filters that keeps a multi-hypothesis estimate of the person being tracked, including the case where the latter is unknown to the robot.
Several experiments with real mobile robots are presented to validate the proposed approach. They show that our solutions can improve the robot's perception and recognition of humans, providing a useful contribution for the future application of service robotics
The Physicist's Guide to the Orchestra
An experimental study of strings, woodwinds (organ pipe, flute, clarinet,
saxophone and recorder), and the voice was undertaken to illustrate the basic
principles of sound production in music instruments. The setup used is simple
and consists of common laboratory equipment. Although the canonical examples
(standing wave on a string, in an open and closed pipe) are easily reproduced,
they fail to explain the majority of the measurements. The reasons for these
deviations are outlined and discussed.Comment: 11 pages, 10 figures (jpg files). Submitted to European Journal of
Physic
Diet induced modifications of fatty-acid composition in mealworm larvae (Tenebrio molitor)
The diet of Western human societies is characterized by an excess of saturated fatty acids (FAs) and a high concentration of ω-6 relative to ω-3 polyunsaturated FA (PUFA). These unbalanced diets are suspected to trigger diseases and disorders. To alleviate this public health concern, the production of healthier meat with more PUFAs of higher ω-3 concentration could potentially be achieved by modifying livestock diets. The high nutritional value and limited breeding costs of edible insects have brought insect feed into the discussion as a promising fat source for animal and human diets. In this study, we sought to increase the amount of ω-3 PUFAs in mealworm (Tenebrio molitor) larvae. We investigated the effects of diets varying in ω-3/ω-6 ratio and FA concentration but similar in PUFA proportion on larva FA composition. Mealworm larvae showed significant plasticity in lipid composition. High dietary ω-3/ω-6 ratios induced an increase in the proportion of ω-3 and a decrease in ω-6, which resulted in higher larval ω-3/ω-6 ratios, but also in higher larval PUFA proportion. Increasing FA concentrations in larva diets also favored the accumulation of PUFAs to the detriment of monounsaturated and saturated FAs. Providing ω-3-rich seeds to mealworm larvae could allow the production of economical animal fat with healthier PUFA percentages (> 60%) and ω-3/ω-6 ratios (>0.5)
Systems Approach Reveals Nuclear Factor Erythroid 2-Related Factor 2/Protein Kinase R Crosstalk in Human Cutaneous Leishmaniasis
Leishmania parasites infect macrophages, causing a wide spectrum of human diseases, from cutaneous to visceral forms. In search of novel therapeutic targets, we performed comprehensive in vitro and ex vivo mapping of the signaling pathways upstream and downstream of antioxidant transcription factor [nuclear factor erythroid 2-related factor 2 (Nrf2)] in cutaneous leishmaniasis (CL), by combining functional assays in human and murine macrophages with a systems biology analysis of in situ (skin biopsies) CL patient samples. First, we show the PKR pathway controls the expression and activation of Nrf2 in Leishmania amazonensis infection in vitro. Nrf2 activation also required PI3K/Akt signaling and autophagy mechanisms. Nrf2- or PKR/Akt-deficient macrophages exhibited increased levels of ROS/RNS and reduced expression of Sod1 Nrf2-dependent gene and reduced parasite load. L. amazonensis counteracted the Nrf2 inhibitor Keap1 through the upregulation of p62 via PKR. This Nrf2/Keap1 observation was confirmed in situ in skin biopsies from Leishmania-infected patients. Next, we explored the ex vivo transcriptome in CL patients, as compared to healthy controls. We found the antioxidant response element/Nrf2 signaling pathway was significantly upregulated in CL, including downstream target p62. In silico enrichment analysis confirmed upstream signaling by interferon and PI3K/Akt, and validated our in vitro findings. Our integrated in vitro, ex vivo, and in silico approach establish Nrf2 as a central player in human cutaneous leishmaniasis and reveal Nrf2/PKR crosstalk and PI3K/Akt pathways as potential therapeutic targets
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