Periodic scarred States in open quantum dots as evidence of quantum Darwinism.

Scanning gate microscopy (SGM) is used to image scar structures in an open quantum dot, which is created in an InAs quantum well by electron-beam lithography and wet etching. The scanned images demonstrate periodicities in magnetic field that correlate to those found in the conductance fluctuations. Simulations have shown that these magnetic transform images bear a strong resemblance to actual scars found in the dot that replicate through the modes in direct agreement with quantum Darwinism.

Imaging scarred states in quantum dots.

We have used the scanning gate microscopy technique to image scar structures in an open quantum dot, fabricated in an InAs quantum well and defined by electron beam lithography. These are shown to have a periodicity in magnetic field that correlates with that found in the conductance fluctuations. Simulations have shown that these magnetic transform images bear a strong resemblance to actual scars found in the dots.

Pancreatic cancer: treatment with neutron irradiation alone and with chemotherapy.

PURPOSE: To evaluate neutron irradiation alone and with chemotherapy to treat inoperable pancreatic cancer. MATERIALS AND METHODS: Between 1977 and 1994, 173 patients (60 men, 113 women, aged 43-77 years [mean, 59 years]) with unresectable adenocarcinoma of the exocrine pancreas were treated, 106 with neutron irradiation alone and 67 with concomitant chemotherapy (fluorouracil [5-FU]). At follow-up, which was performed at 2-month intervals until death (range, 4-64 months), clinical status was recorded, noting the presence of overt metastasis and the onset of any major complications. Actuarial (Kaplan-Meier) survival tables were computed for both groups. RESULTS: For neutron irradiation alone and neutron irradiation plus chemotherapy, median survival times were 6 months and 9 months, respectively; actuarial survival rates at 3 years were 0 and 7%, respectively; major reactions (grade 3 or higher [scale of the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer]) occurred in 19 (18%) and 17 (25%) patients, respectively; and severe complications (grade 4) occurred in five (5%) and four (6%) patients, respectively. Most deaths were due to metastatic disease rather than to failure of local control. CONCLUSIONS: Neutron irradiation obliterated pancreatic adenocarcinoma at the primary site but has no effect on long-term survival. With more effective concomitant chemotherapy to prevent metastasis, local control of pancreatic cancer with neutron irradiation could lead to increased long-term survival.

Electro-optic Fabry-Perot pixels for phase-dominant spatial light modulators.

A theoretical analysis of phase enhancement by resonant Fabry-Perot picture elements in III-V semiconductor spatial light modulators (SLM's) is presented. For 90% reflecting electrodes, a phase modulation of 0.7pi rad is found in transmission when the electro-optic input phase is 0.06pi rad. Implementation of this resonant phase-dominant SLM in a 1.5-microm-thick AlGaAs/GaAs multiple quantum well (MQW) structure is proposed. Field effects and carrier-induced electro-optic effects are suggested for the MQW's.

Incidence, costs, and DRG-based reimbursement for traumatic brain injured patients: a 3-year experience.

A 3-year prospective study was conducted to establish the incidence of traumatic brain injury (TBI) and related characteristics of age, sex, length of stay (LOS), intensive care unit LOS (ICU/LOS), direct hospital charges, and reimbursement using a prospective DRG-based reimbursement system. The study identified TBI patients using ICD-9-Codes. The mean LOS for the two groups of patients with intracranial injury differed (p less than 0.05). Those with such an injury accompanied by a fracture stayed 1.8 days less in the ICU and 6.0 days less overall. Direct hospital charges for all TBI patients were $14,138,036 (mean, $11,645). Using Medicare weights and hospital-specific rates/DRG, the DRG reimbursement was $6,689,293. Thirty-day outliers (those who stayed ten times the geometric mean length of stay) provided an additional $526,389 leaving a total non-reimbursable figure of $6,922,354, or 49% of total charges. Of the 71 DRGs assigned to the study population, 15 reimbursed more than the actual charges. The severity of TBI victims and the complexity of caring for them in a Level I trauma center generates hospital charges of which only half are reimbursed through an all-payor DRG system. Strategies to correct what could be a financial disincentive are: documenting the uniqueness of this population to justify additional reimbursement, calculating a more precise mean LOS for TBI-related DRGs to more accurately identify outliers, and calculating DRG rates for TBI diagnoses derived from a representative sample at varying severity levels and hospitalized in facilities with and without rehabilitation services.

Carrier refraction in quantum well waveguides.

Carrier-induced refractive index changes in forward-biased InGaAs-InAlAs quantum well waveguides are calculated using a Kramers-Kronig transformation of Bar-Joseph's experimental absorption spectra [Phys. Rev. Lett. 59, 1357 (1987)]. At the l.65-,microm wavelength where the material is nominally transparent, an index change of -0.06 is found for an injection of 6 x 10(17) electrons/cm(3) . A quantum well waveguide 2 x 2 reversed-Deltabeta directional coupler switch with an active length of 480 microm is proposed.

Analysis of personnel exposures in neutron therapy facilities.

In conventional radiation-therapy facilities, radiation doses to medical personnel originate from the leakage radiation of 60Co teletherapy systems or from photoneutrons produced during the operation of x-ray generators at energies over 10 MeV in unsuitably shielded therapy rooms. In neutron-therapy facilities, during patient set-ups and position verifications, medical personnel are exposed to photons from remanent radioactivity induced in the shielding around the neutron-producing targets and in the beam collimators. At Fermilab, the use of an elevating platform limits personnel exposure periods to those times when collimators are being exchanged. Comparisons with other facilities are shown.