2,685 research outputs found
Intraduodenal sarcoma recurrence of retroperitoneal origin: an unusual cause for a duodenal obstruction.
Soft tissue sarcomas are uncommon tumors, and intraduodenal soft tissue sarcoma manifestation is even more rare. Only three cases of intraduodenal sarcomas have been reported in the literature thus far. Here, we report a case of an intraduodenal recurrence of a retroperitoneal sarcoma causing bowel obstruction. This unusual recurrence pattern likely relates to the patient's previous resection and radiation treatment, and highlights the benefits, limitations and follow-up strategies after multimodality treatment
Evidence for Non-perturbative String Symmetries
String theory appears to admit a group of discrete field transformations --
called dualities -- as exact non-perturbative quantum symmetries.
Mathematically, they are rather analogous to the better-known duality
symmetries, which hold perturbatively. In this talk the evidence for
duality is reviewed and some speculations are presented.Comment: Error corrected and reference added; 10 pages, latex, no figures,
conference Repor
Self-Assembled Triply Periodic Minimal Surfaces as moulds for Photonic Band Gap Materials
We propose systems with structures defined by self-assembled triply periodic
minimal surfaces (STPMS) as candidates for photonic bandgap materials. To
support our proposal we have calculated the photonic bands for different STPMS
and we have found that, at least, the double diamond and gyroid structures
present full photonic bandgaps. Given the great variety of systems which
crystalize in these structures, the diversity of possible materials that form
them and the range of lattice constants they present, the construction of
photonic bandgap materials with gaps in the visible range may be presently
within reach.Comment: 3 pages, 2 figures, RevTe
And in the Darkness Bind Them: Equatorial Rings, B[e] Supergiants, and the Waists of Bipolar Nebulae
We report the discovery of two new circumstellar ring nebulae in the western
Carina Nebula. The brighter object, SBW1, resembles a lidless staring eye and
encircles a B1.5 Iab supergiant. Its size is identical to the inner ring around
SN1987A, but SBW1's low N abundance indicates that the star didn't pass through
a RSG phase. The fainter object, SBW2, is a more distorted ring, is N-rich, and
has a central star that seems to be invisible. We discuss these two new nebulae
in context with rings around SN1987A, Sher25, HD168625, RY Scuti, WeBo1, SuWt2,
and others. The ring bearers fall into two groups: Five rings surround hot
supergiants, and all except for the one known binary are carbon copies of the
ring around SN1987A. We propose a link between these rings and B[e]
supergiants, where the rings derive from the same material in an earlier B[e]
phase. The remaining four rings surround evolved intermediate-mass stars; all
members of this ring fellowship are close binaries, hinting that binary
interactions govern the forging of such rings. We estimate that there may be
several thousand more dark rings in the Galaxy, but we are scarcely aware of
their existence due to selection effects. The lower-mass objects might be the
equatorial density enhancements often invoked to bind the waists of bipolar
PNe.Comment: AJ accepted, 27 page
Serum squamous cell carcinoma antigen as an early indicator of response during therapy of cervical cancer
Probing the Gas Content of Late-stage Protoplanetary Disks with N_2H^+
The lifetime of gas in circumstellar disks is a fundamental quantity that informs our understanding of planet formation. Studying disk gas evolution requires measurements of disk masses around stars of various ages. Because H_2 gas is unobservable under most disk conditions, total disk masses are based on indirect tracers such as sub-mm dust and CO emission. The uncertainty in the relation between these tracers and the disk mass increases as the disk evolves. In a few well-studied disks, CO exhibits depletions of up to 100× below the assumed interstellar value. Thus, additional tracers are required to accurately determine the total gas mass. The relative lack of nitrogen found in solid solar system bodies may indicate that it persists in volatile form, making nitrogen-bearing species more robust tracers of gas in more evolved disks. Here we present Atacama Large Millimeter/submillimeter Array detections of N_2H^+ in two mature, ~5–11 Myr old disks in the Upper Scorpius OB Association. Such detections imply the presence of H_2-rich gas and sources of ionization, both required for N_2H^+ formation. The Upper Sco disks also show elevated N_2H^+/CO flux ratios when compared to previously observed disks with ≳10× higher CO fluxes. Based on line ratio predictions from a grid of thermochemical disk models, a significantly reduced CO/H_2 abundance of <10^(−6) for a gas-to-dust ratio of ≳100 is required to produce the observed N_2H^+ fluxes. These systems appear to maintain H_2 gas reservoirs and indicate that carbon- and nitrogen-bearing species follow distinct physical or chemical pathways as disks evolve
Pennsylvania Folklife Vol. 43, No. 2
• The America\u27s Industrial Heritage Project: A Model for Cultural Tourism • The Harmonists are Waiting for You • The Quest for Authenticity in Tourism and Folklife Studies • Tourism and the Old Order Amish • The Log Cabin: Notes on its Structure and Dissemination • On the Making of Die Union Choral Harmonie (1833): Evidence from Henry C. Eyer\u27s Working Papers • In Memoriam: Paul R. Wieand, a True Artisthttps://digitalcommons.ursinus.edu/pafolklifemag/1139/thumbnail.jp
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