395 research outputs found
The Stability of Bredigite and Other Ca-Mg Silicates
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65844/1/j.1151-2916.1980.tb10213.x.pd
Challenges and pitfalls of experimental bariatric procedures in rats
Introduction: The impact of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on obesity and obesity-related diseases is unquestionable. Up to now, the technical descriptions of these techniques in animals/rats have not been very comprehensive. Methods: For SG and RYGB, operating time, learning curve, and intraoperative mortality in relation to weight of the rat and type of anesthesia were recorded. Furthermore, a review of the literature on experimental approaches towards SG and RYGB in rats was carried out, merging in a detailed technical description for both procedures. Results: The data presented here revealed that the mean operating time for SG (69.4 +/- 22.2 min (SD)) was shorter than for RYGB (123.0 +/- 20.7 min). There is a learning curve for both procedures, resulting in a reduced operating time of up to 60% in SG and 35% in RYGB (p < 0.05; t-test). However, with increased weight, operating time increases to about 80 min for SG and about 120 min for RYGB. Obese rats have an increased intraoperative mortality rate of up to 50%. After gaseous anesthesia the mortality can be even higher. The literature search revealed 40 papers dealing with SG and RYGB in rats. 18 articles (45%) contained neither photographs nor illustrations; 14 articles (35%) did not mention the applied type of anesthesia. The mortality rate was described in 15 papers (37.5%). Conclusion: Experimental obesity surgery in rats is challenging. Because of the high mortality in obese rats operated under gaseous anesthesia, exercises to establish the techniques should be performed in small rats using intraperitoneal anesthesia. Copyright (C) 2012 S. Karger GmbH, Freibur
LigaSure Impact™ versus conventional dissection technique in pylorus-preserving pancreatoduodenectomy in clinical suspicion of cancerous tumours on the head of the pancreas: study protocol for a randomised controlled trial
<p>Abstract</p> <p>Background</p> <p>The pp-Whipple procedure requires extensive preparation. The conventional preparation technique is done with scissors for dissection and ligatures, and with clips and sutures for hemostasis. This procedure is very time-consuming and requires numerous changes of instruments. The LigaSure™ device allows dissection and hemostasis for preparation with one instrument. Up to now there has been no comparison of the two techniques with regard to operating time and the patients' outcome. It is still unclear which technique has the optimal benefit/risk ratio for the patient.</p> <p>Methods/Design</p> <p>A single-center, randomized, single-blinded, controlled superiority trial to compare two different techniques for dissection in a pp-Whipple procedure. 102 patients will be included and randomized pre-operatively. All patients aged 18 years or older scheduled for primary elective pp-Whipple procedure who signed the informed consent will be included. The primary endpoint is the operating time of the randomized technique. Control Intervention: Conventional dissection technique; experimental intervention: LigaSureTM dissection technique. Duration of study: Approximately 15 months; follow up time: 3 years. The trial is registered at German ClinicalTrials Register (DRKS00000166).</p
The Hopf Algebra of Renormalization, Normal Coordinates and Kontsevich Deformation Quantization
Using normal coordinates in a Poincar\'e-Birkhoff-Witt basis for the Hopf
algebra of renormalization in perturbative quantum field theory, we investigate
the relation between the twisted antipode axiom in that formalism, the Birkhoff
algebraic decomposition and the universal formula of Kontsevich for quantum
deformation.Comment: 21 pages, 15 figure
Star products made (somewhat) easier
We develop an approach to the deformation quantization on the real plane with
an arbitrary Poisson structure which based on Weyl symmetrically ordered
operator products. By using a polydifferential representation for deformed
coordinates we are able to formulate a simple and effective
iterative procedure which allowed us to calculate the fourth order star product
(and may be extended to the fifth order at the expense of tedious but otherwise
straightforward calculations). Modulo some cohomology issues which we do not
consider here, the method gives an explicit and physics-friendly description of
the star products.Comment: 20 pages, v2, v3: comments and references adde
Morita Equivalence, Picard Groupoids and Noncommutative Field Theories
In this article we review recent developments on Morita equivalence of star
products and their Picard groups. We point out the relations between
noncommutative field theories and deformed vector bundles which give the Morita
equivalence bimodules.Comment: Latex2e, 10 pages. Conference Proceeding for the Sendai Meeting 2002.
Some typos fixe
Shelf ice-associated cryo-benthos and environmental features
Incidences of cryo-benthic communities beneath ice shelves are rare and recent discoveries. Combined seal- and ROV-borne imagery and novel sampling technologies allowed for a re-assessment and augmentation of earlier findings on a cryo-benthic isopod community (Antarcturus cf. spinacoronatus), being attached head-down to the underside of floating shelf ice at depths of around 80-150m. The shelf ice-associated cryo-benthos was discovered at Drescher Inlet (-72.83667 -19.15300), Riiser-Larsen Ice Shelf (eastern Weddell Sea). The inlet constitutes a 25km long and between 2 and 4km wide crack in the surrounding shelf ice, which is associated with certain environmental features. Here we compile all available local physical, biological, and biogeochemical data and discuss their relevance in the wider regional context for this faunal hotspot. These include data on shelf, sea and platelet ice, seafloor topography, hydrography and water chemistry, as well as associated pelagic and benthic marine life, in particular affinities of the cryo-benthic isopod community to related fauna occurring in nearby seabed communities using molecular barcoding
Configuration of the Northern Antarctic Peninsula Ice Sheet at LGM based on a new synthesis of seabed imagery
We present a new seafloor map for the northern
Antarctic Peninsula (AP), including swath multibeam data
sets from five national programs. Our map allows for the
examination and interpretation of Last Glacial Maximum
(LGM) paleo-ice-flow paths developed on the seafloor from
the preservation of mega-scale glacial lineations, drumlinized
features, and selective linear erosion. We combine this
with terrestrial observations of flow direction to place constraints
on ice divides and ice domes on the AP continental
shelf during the LGM time interval. The results show a flow
bifurcation as ice exits the Larsen B embayment. Flow emanating
off the Seal Nunataks (including Robertson Island)
is directed toward the southeast, then eastward as the flow
transits toward the Robertson Trough. A second, stronger
“streaming flow” is directed toward the southeast, then southward
as ice overflowed the tip of the Jason Peninsula to reach
the southern perimeter of the embayment. Our reconstruction
also refines the extent of at least five other distinct paleo-icestream
systems that, in turn, serve to delineate seven broad
regions where contemporaneous ice domes must have been
centered on the continental shelf at LGM. Our reconstruction
is more detailed than other recent compilations because we
followed specific ice-flow indicators and have kept tributary
flow paths parallel
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