1,446 research outputs found
Effect of Lethally Damaged Tumour Cells upon the Growth of Admixed Viable Cells in Diffusion Chambers
IT has been shown that the proliferation of a small viable tumour graft is stimulated by the presence of irreversibly X-ray damaged tumour cells (Revesz, 1958) or viable but genetically incompatible cells (Klein and Klein, 1956). Histological examination (Ringertz, Klein and Revesz, 1959) showed an enhanced granulation tissue formation in and around the implant. The intensity of this reaction was parallel to the stimulating effect of X-ray damaged, genetically incompatible, and heat-killed cells, respectively. This would indicate that the stimulating function may depend on the formation of a proper tumour bed. In addition, a direct " feeder " effect (Puck, Marcus and Cieciura, 1956) may also play a certain role sinice heavily irradiated cells were stimulatory even in the case of freely suspended ascites tumour cells (Revesz, 1955; Scott, 1957; Mazurek and Duplan, 1959). The diffusion chamber technique of Algire, Weaver and Prehn (1954) permits the isolation of the graft from direct contact with host cells. Filter membraines with adequately small pores permit the diffusion of soluble materials but preven
Pancreatic Resections for Advanced M1-Pancreatic Carcinoma: The Value of Synchronous Metastasectomy
Background. For M1 pancreatic adenocarcinomas pancreatic resection is usually not indicated. However, in highly selected patients synchronous metastasectomy may be appropriate together with pancreatic resection when operative morbidity is low.
Materials and Methods. From January 1, 2004 to December, 2007 a total of 20 patients with pancreatic malignancies were retrospectively evaluated who underwent pancreatic surgery with synchronous resection of hepatic, adjacent organ, or peritoneal metastases for proven UICC stage IV periampullary cancer of the pancreas. Perioperative as well as clinicopathological parameters were evaluated.
Results. There were 20 patients (9 men, 11 women; mean age 58 years) identified. The primary tumor was located in the pancreatic head (n = 9, 45%), in pancreatic tail (n = 9, 45%), and in the papilla Vateri (n = 2, 10%). Metastases were located in the liver (n = 14, 70%), peritoneum (n = 5, 25%), and omentum majus (n = 2, 10%). Lymphnode metastases were present in 16 patients (80%). All patients received resection of their tumors together with metastasectomy. Pylorus preserving duodenopancreatectomy was performed in 8 patients, distal pancreatectomy in 8, duodenopancreatectomy in 2, and total pancreatectomy in 2. Morbidity was 45% and there was no perioperative mortality. Median postoperative survival was 10.7 months (2.6–37.7 months) which was not significantly different from a matched-pair group of patients who underwent pancreatic resection for UICC adenocarcinoma of the pancreas (median survival 15.6 months; P = .1). Conclusion. Pancreatic resection for M1 periampullary cancer of the pancreas can be performed safely in well-selected patients. However, indication for surgery has to be made on an individual basis
Electron-phonon scattering in quantum point contacts
We study the negative correction to the quantized value of the
conductance of a quantum point contact due to the backscattering of electrons
by acoustic phonons. The correction shows activated temperature dependence and
also gives rise to a zero-bias anomaly in conductance. Our results are in
qualitative agreement with recent experiments studying the 0.7 feature in the
conductance of quantum point contacts.Comment: 4 pages, no figure
On-Campus Solar PV Lab: Component Selection is Only the Beginning
The work of the Solar PV Team is to design and install Solar PV systems which enable our clients to fulfill their mission in the presence of unreliable or non-existent electrical power. In order to experiment with different Solar PV configurations and train new members, the Solar PV team last year designed a Solar Lab to be installed in and next to Frey 70. This work paralleled the design/component selection typically performed prior to an installation site trip. This year, the team modeled the efforts typically done at the installation site by building and configuring the Solar Lab design. This poster will focus on the lessons learned about decisions that need to be made in the field to convert a Component Selection level design into a Functioning PV System.https://mosaic.messiah.edu/engr2021/1015/thumbnail.jp
On-Campus Solar PV Lab: Component Selection is Only the Beginning
The work of the Solar PV Team is to design and install Solar PV systems which enable our clients to fulfill their mission in the presence of unreliable or non-existent electrical power. In order to experiment with different Solar PV configurations and train new members, the Solar PV team last year designed a Solar Lab to be installed in and next to Frey 70. This work paralleled the design/component selection typically performed prior to an installation site trip. This year, the team modeled the efforts typically done at the installation site by building and configuring the Solar Lab design. This poster will focus on the lessons learned about decisions that need to be made in the field to convert a Component Selection level design into a Functioning PV System.https://mosaic.messiah.edu/engr2021/1003/thumbnail.jp
Binary pattern tile set synthesis is NP-hard
In the field of algorithmic self-assembly, a long-standing unproven
conjecture has been that of the NP-hardness of binary pattern tile set
synthesis (2-PATS). The -PATS problem is that of designing a tile assembly
system with the smallest number of tile types which will self-assemble an input
pattern of colors. Of both theoretical and practical significance, -PATS
has been studied in a series of papers which have shown -PATS to be NP-hard
for , , and then . In this paper, we close the
fundamental conjecture that 2-PATS is NP-hard, concluding this line of study.
While most of our proof relies on standard mathematical proof techniques, one
crucial lemma makes use of a computer-assisted proof, which is a relatively
novel but increasingly utilized paradigm for deriving proofs for complex
mathematical problems. This tool is especially powerful for attacking
combinatorial problems, as exemplified by the proof of the four color theorem
by Appel and Haken (simplified later by Robertson, Sanders, Seymour, and
Thomas) or the recent important advance on the Erd\H{o}s discrepancy problem by
Konev and Lisitsa using computer programs. We utilize a massively parallel
algorithm and thus turn an otherwise intractable portion of our proof into a
program which requires approximately a year of computation time, bringing the
use of computer-assisted proofs to a new scale. We fully detail the algorithm
employed by our code, and make the code freely available online
Probe-configuration dependent dephasing in a mesoscopic interferometer
Dephasing in a ballistic four-terminal Aharonov-Bohm geometry due to charge
and voltage fluctuations is investigated. Treating two terminals as voltage
probes, we find a strong dependence of the dephasing rate on the probe
configuration in agreement with a recent experiment by Kobayashi et al. (J.
Phys. Soc. Jpn. 71, 2094 (2002)). Voltage fluctuations in the measurement
circuit are shown to be the source of the configuration dependence.Comment: 4 pages, 3 figure
Synthesis and Interactions of 7-Deoxy-, 10-Deacetoxy, and 10-Deacetoxy-7-Deoxypaclitaxel with NCI/ADR-RES Cancer Cells and Bovine Brain Microvessel Endothelial Cells
Please note that this is an author-produced PDF of an article accepted for publication following peer review. The publisher version is available on its site.7-Deoxypaclitaxel, 10-deacetoxypaclitaxel and 10-deacetoxy-7-deoxypaclitaxel were prepared and evaluated for their ability
to promote assembly of tubulin into microtubules, their cytotoxicity against NCI/ADR-RES cells and for their interactions with Pglycoprotein
in bovine brain microvessel endothelial cells. The three compounds were essentially equivalent to paclitaxel in cytotoxicity
against NCI/ADR-RES cells. They also appeared to interact with P-glycoprotein in the endothelial cells with the two 10-deacetoxy
compounds having less interaction than paclitaxel and 7-deoxypaclitaxel. ©2000 Elsevier Science Ltd. All rights reserved
Electron fractionalization induced dephasing in Luttinger liquids
Using the appropriate fractionalization mechanism, we correctly derive the
temperature (T) and interaction dependence of the electron lifetime in
Luttinger liquids. For strong enough interactions, we report that
, with being the standard Luttinger exponent; This
reinforces that electrons are {\it not} good quasiparticles. We immediately
emphasize that this is of importance for the detection of electronic
interferences in ballistic 1D rings and carbon nanotubes, inducing
``dephasing'' (strong reduction of Aharonov-Bohm oscillations).Comment: 5 pages, 1 figure (Final version for PRB Brief Report
Intramolecular and Lattice Melting in n-Alkane Monolayers: An Analog of Melting in Lipid Bilayers
URL:http://link.aps.org/doi/10.1103/PhysRevLett.83.2362
DOI:10.1103/PhysRevLett.83.2362Molecular dynamics (MD) simulations and neutron diffraction experiments have been performed on n-dotriacontane ( n-C32D66) monolayers adsorbed on a graphite basal- plane surface. The diffraction experiments show little change in the crystalline monolayer structure up to a temperature of ~350K above which a large thermal expansion and decrease in coherence length occurs. The MD simulations provide evidence that this behavior is due to a phase transition in the monolayer in which intramolecular and translational order are lost simultaneously. This melting transition is qualitatively similar to the gel-to-fluid transition found in bilayer lipid membranes.Acknowledgment is made to the U.S. National Science Foundation under Grants No. DMR-9314235 and No. DMR-9802476, the Missouri University Research Reactor, and to the donors of The Petroleum Research Fund, administered by the ACS, for partial support of this research. We thank L. Criswell for assistance with the figures
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