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Search Results: 1 - 10 of 114759 matches for " Peter W. Hanson "
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A concise review of the efficacy of stereotactic radiosurgery in the management of melanoma and renal cell carcinoma brain metastases
Hanson Peter W,Elaimy Ameer L,Lamoreaux Wayne T,Demakas John J
World Journal of Surgical Oncology , 2012, DOI: 10.1186/1477-7819-10-176
Abstract: Melanoma and renal cell carcinoma have a well-documented tendency to develop metastases to the brain. Treating these lesions has traditionally been problematic, because chemotherapy has difficulty crossing the blood brain barrier and whole brain radiation therapy (WBRT) is a relatively ineffective treatment against these radioresistant tumor histologies. In recent years, stereotactic radiosurgery (SRS) has emerged as an effective and minimally-invasive treatment modality for irradiating either single or multiple intracranial structures in one clinical treatment setting. For this reason, we conducted a review of modern literature analyzing the efficacy of SRS in the management of patients with melanoma and renal cell carcinoma brain metastases. In our analysis we found SRS to be a safe, effective and attractive treatment modality for managing radioresistant brain metastases and highlighted the need for randomized trials comparing WBRT alone vs. SRS alone vs. WBRT plus SRS in treating patients with radioresistant brain metastases.
A Data Analysis Technique for the LIGO-ALLEGRO Stochastic Background Search
John T. Whelan,Sukanta Bose,Jonathan Hanson,Ik Siong Heng,Warren W. Johnson,Martin P. McHugh,Peter Zhang
Physics , 2005, DOI: 10.1088/0264-9381/22/18/S23
Abstract: We describe the cross-correlation measurements being carried out on data from the LIGO Livingston Observatory and the ALLEGRO resonant bar detector. The LIGO data are sampled at 16384 Hz while the ALLEGRO data are base-banded, i.e., heterodyned at 899 Hz and then sampled at 250 Hz. We handle these different sampling parameters by working in the Fourier domain, and demonstrate the approximate equivalence of this measurement to a hypothetical time-domain method in which both data streams are upsampled.
Dyadic Green's Functions and Guided Surface Waves for a Surface Conductivity Model of Graphene
George W. Hanson
Physics , 2007, DOI: 10.1063/1.2891452
Abstract: An exact solution is obtained for the electromagnetic field due to an electric current in the presence of a surface conductivity model of graphene. The graphene is represented by an infinitesimally-thin, local and isotropic two-sided conductivity surface. The field is obtained in terms of dyadic Green's functions represented as Sommerfeld integrals. The solution of plane-wave reflection and transmission is presented, and surface wave propagation along graphene is studied via the poles of the Sommerfeld integrals. For isolated graphene characterized by complex surface conductivity, a proper transverse-electric (TE) surface wave exists if and only if the imaginary part of conductivity is positive (associated with interband conductivity), and a proper transverse-magnetic (TM) surface wave exists when the imaginary part of conductivity is negative (associated with intraband conductivity). By tuning the chemical potential at infrared frequencies, the sign of the imaginary part of conductivity can be varied, allowing for some control over surface wave properties.
Clinical Outcomes of Gamma Knife Radiosurgery in the Treatment of Patients with Trigeminal Neuralgia
Ameer L. Elaimy,Peter W. Hanson,Wayne T. Lamoreaux,Alexander R. Mackay,John J. Demakas,Robert K. Fairbanks,Barton S. Cooke,Sudheer R. Thumma,Christopher M. Lee
International Journal of Otolaryngology , 2012, DOI: 10.1155/2012/919186
Abstract: Since its introduction by Leksell, Gamma Knife radiosurgery (GKRS) has become increasingly popular as a management approach for patients diagnosed with trigeminal neuralgia (TN). For this reason, we performed a modern review of the literature analyzing the efficacy of GKRS in the treatment of patients who suffer from TN. For patients with medically refractory forms of the condition, GKRS has proven to be an effective initial and repeat treatment option. Cumulative research suggests that patients treated a single time with GKRS exhibit similar levels of facial pain control when compared to patients treated multiple times with GKRS. However, patients treated on multiple occasions with GKRS are more likely to experience facial numbness and other facial sensory changes when compared to patients treated once with GKRS. Although numerous articles have reported MVD to be superior to GKRS in achieving facial pain relief, the findings of these comparison studies are weakened by the vast differences in patient age and comorbidities between the two studied groups and cannot be considered conclusive. Questions remain regarding optimal GKRS dosing and targeting strategies, which warrants further investigation into this controversial matter.
Effect of pretreatment clinical factors on overall survival in glioblastoma multiforme: a Surveillance Epidemiology and End Results (SEER) population analysis
Sudheer R Thumma, Robert K Fairbanks, Wayne T Lamoreaux, Alexander R Mackay, John J Demakas, Barton S Cooke, Ameer L Elaimy, Peter W Hanson, Christopher M Lee
World Journal of Surgical Oncology , 2012, DOI: 10.1186/1477-7819-10-75
Abstract: We used the Surveillance, Epidemiology, and End Results (SEER) database of the US National Cancer Institute (NCI) to investigate various patient-related and treatment- related factors that could influence the long term survival in patients diagnosed with glioblastoma. A total of 34,664 patients aged 20?years or older with a diagnosis of GBM during the years 1973 to 2008 were studied. Overall survival outcomes were examined with Kaplan-Meier survival analysis and Cox hazard models.Asian/Pacific Islanders had a better survival compared to the white population (P?=?<0.001). Patients diagnosed with GBM during the years 2000 to 2008 had a superior survival rate when compared with earlier decades (P?=?<0 .001). Statistically significant improvements in overall survival were also found for patients who received surgical resections, and adjuvant radiation treatment versus no radiation (P-values <0.001). Young age was also found to be highly predictive of improved overall survival rates when separated into age groups as well as when studied as a continuous variable.Clinical pretreatment and treatment factors, including young age at diagnosis, Asian/Pacific Islander ethnicity, recent year of diagnosis, surgical resection and the use of adjuvant radiation therapy favorably influence survival in patients diagnosed with glioblastoma.All data were obtained from the United States Surveillance Epidemiology and End Results (SEER) database.
Clinical Outcomes of Gamma Knife Radiosurgery in the Treatment of Patients with Trigeminal Neuralgia
Ameer L. Elaimy,Peter W. Hanson,Wayne T. Lamoreaux,Alexander R. Mackay,John J. Demakas,Robert K. Fairbanks,Barton S. Cooke,Sudheer R. Thumma,Christopher M. Lee
International Journal of Otolaryngology , 2012, DOI: 10.1155/2012/919186
Abstract: Since its introduction by Leksell, Gamma Knife radiosurgery (GKRS) has become increasingly popular as a management approach for patients diagnosed with trigeminal neuralgia (TN). For this reason, we performed a modern review of the literature analyzing the efficacy of GKRS in the treatment of patients who suffer from TN. For patients with medically refractory forms of the condition, GKRS has proven to be an effective initial and repeat treatment option. Cumulative research suggests that patients treated a single time with GKRS exhibit similar levels of facial pain control when compared to patients treated multiple times with GKRS. However, patients treated on multiple occasions with GKRS are more likely to experience facial numbness and other facial sensory changes when compared to patients treated once with GKRS. Although numerous articles have reported MVD to be superior to GKRS in achieving facial pain relief, the findings of these comparison studies are weakened by the vast differences in patient age and comorbidities between the two studied groups and cannot be considered conclusive. Questions remain regarding optimal GKRS dosing and targeting strategies, which warrants further investigation into this controversial matter. 1. Introduction Trigeminal neuralgia (TN) is a disorder of cranial nerve (CN) V that results in severe episodes of shock-like or lancinating pain in one or more of its three divisions (V1–V3). TN can be classified into two categories based on etiology: classical and symptomatic [1]. Idiopathic TN and cases due to vascular compression of CN V are categorized as classical TN [1]. Patients diagnosed with symptomatic TN experience trigeminal-related facial pain secondary to a brain tumor, skull deformity, or multiple sclerosis (MS) [1]. Evidence suggests that the majority of cases of TN are the consequence of focal compression of the entry zone of the root of the trigeminal nerve [2], while only 2% of cases are observed in patients diagnosed with MS [3]. Other than excruciating facial pain, there are no other direct medical symptoms associated with TN, and the condition does not decrease life expectancy. However, many patients with TN struggle with accomplishing tasks that affect quality of life, which is how this disorder elicits a negative impact on the social and mental wellness of the patients who suffer from this illness. Following the diagnosis of TN, pharmacotherapy is often the initial management approach in achieving facial pain control. However, many patients experience only limited relief from medication or are unable to
Soft-boundary graphene nanoribbon formed by a graphene sheet above a perturbed ground plane: conductivity profile and SPP modal current distribution
Ebrahim Forati,George W. Hanson
Physics , 2013, DOI: 10.1088/2040-8978/15/11/114006
Abstract: An infinite sheet of graphene lying above a perturbed ground plane is studied. The perturbation is a two dimensional ridge, and a bias voltage is applied between the graphene and the ground plane, resulting in a graphene nanoribbonlike structure with a soft-boundary (SB) The spatial distribution of the graphene conductivity forming the soft-boundary is studied as a function of the ridge parameters and the bias voltage. The current distribution of the fundamental TM surface plasmon polariton (SPP) is considered. The effect of the ridge parameters and shape of the soft boundary on the current distributions are investigated, and the conditions are studied under which the mode remains confined to the vicinity of the ridge region.
Surface plasmon polaritons on soft-boundary graphene nanoribbons and their application as voltage controlled plasmonic switches and frequency demultiplexers
Ebrahim Forati,George W. Hanson
Physics , 2013, DOI: 10.1063/1.4822044
Abstract: A graphene sheet gated with a ridged ground plane, creating a soft-boundary (SB) graphene nanoribbon, is considered. By adjusting the ridge parameters and bias voltage a channel can be created on the graphene which can guide TM surface plasmon polaritons (SPP). Two types of modes are found; fundemental and higher-order modes with no apparent cutoff frequency and with energy distributed over the created channel, and edge modes with energy concen-trated at the soft-boundary edge. Dispersion curves, electric near-field patterns, and current distributions of these modes are determined. Since the location where energy is concentrated in the edge modes can be easily controlled electronically by the bias voltage and frequency, the edge-mode phenomena is used to propose a novel voltage controlled plasmonic switch and a plasmonic frequency demultiplexer.
A Contracted DNA Repeat in LHX3 Intron 5 Is Associated with Aberrant Splicing and Pituitary Dwarfism in German Shepherd Dogs
Annemarie M. W. Y. Voorbij, Frank G. van Steenbeek, Manon Vos-Loohuis, Ellen E. C. P. Martens, Jeanette M. Hanson-Nilsson, Bernard A. van Oost, Hans S. Kooistra, Peter A. Leegwater
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027940
Abstract: Dwarfism in German shepherd dogs is due to combined pituitary hormone deficiency of unknown genetic cause. We localized the recessively inherited defect by a genome wide approach to a region on chromosome 9 with a lod score of 9.8. The region contains LHX3, which codes for a transcription factor essential for pituitary development. Dwarfs have a deletion of one of six 7 bp repeats in intron 5 of LHX3, reducing the intron size to 68 bp. One dwarf was compound heterozygous for the deletion and an insertion of an asparagine residue in the DNA-binding homeodomain of LHX3, suggesting involvement of the gene in the disorder. An exon trapping assay indicated that the shortened intron is not spliced efficiently, probably because it is too small. We applied bisulfite conversion of cytosine to uracil in RNA followed by RT-PCR to analyze the splicing products. The aberrantly spliced RNA molecules resulted from either skipping of exon 5 or retention of intron 5. The same splicing defects were observed in cDNA derived from the pituitary of dwarfs. A survey of similarly mutated introns suggests that there is a minimal distance requirement between the splice donor and branch site of 50 nucleotides. In conclusion, a contraction of a DNA repeat in intron 5 of canine LHX3 leads to deficient splicing and is associated with pituitary dwarfism.
Graphene as a tunable THz reservoir for shaping the Mollow triplet of an artificial atom via plasmonic effects
Ebrahim Forati,George W. Hanson,Stephen Hughes
Physics , 2014, DOI: 10.1103/PhysRevB.90.085414
Abstract: Using a realistic quantum master equation we show that the resonance fluorescence spectra of a two-level artificial atom (quantum dot) can be tuned by adjusting its photonic local density of states via biasing of one or more graphene monolayers. The structured photon reservoir is included using a photon Green function theory which fully accounts for the loss and dispersion. The field-driven Mollow triplet spectrum can be actively controlled by the graphene bias in the THz frequency regime. We also consider the effect of a dielectric support environment, and multiple graphene layers, on the emitted fluorescence. Finally, thermal bath effects are considered and shown to be important for low THz frequencies.
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