On the merit of a Central Limit Theorem-based approximation in statistical physics

The applicability conditions of a recently reported Central Limit Theorem-based approximation method in statistical physics are investigated and rigorously determined. The failure of this method at low and intermediate temperature is proved as well as its inadequacy to disclose quantum criticalities at fixed temperatures. Its high temperature predictions are in addition shown to coincide with those stemming from straightforward appropriate expansions up to (k_B T)^(-2). Our results are clearly illustrated by comparing the exact and approximate temperature dependence of the free energy of some exemplary physical systems.Comment: 12 pages, 1 figur

The Impact of Interorganizational Imitation on New Venture International Entry and Performance

We examine the impact of interorganizational imitation on new venture international entry and subsequent performance. Using a sample of 150 U.S.-based publicly held new ventures, we find that new venture international entry is in part an imitative response to the internationalization of other firms in the venture\u27s home country industry and/or subsets of firms with certain traits or outcomes. We also find that interorganizational imitation moderates the relationship between new venture international entry and profitability, but not the relationship between new venture international entry and sales growth. These findings contribute to the growing body of literature on new venture internationalization

Semiclassical theory of shot noise in ballistic n+-i-n+ semiconductor strucutres: relevance of Pauli and long range Coulomb correlations

We work out a semiclassical theory of shot noise in ballistic n+-i-n+ semiconductor structures aiming at studying two fundamental physical correlations coming from Pauli exclusion principle and long range Coulomb interaction. The theory provides a unifying scheme which, in addition to the current-voltage characteristics, describes the suppression of shot noise due to Pauli and Coulomb correlations in the whole range of system parameters and applied bias. The whole scenario is summarized by a phase diagram in the plane of two dimensionless variables related to the sample length and contact chemical potential. Here different regions of physical interest can be identified where only Coulomb or only Pauli correlations are active, or where both are present with different relevance. The predictions of the theory are proven to be fully corroborated by Monte Carlo simulations.Comment: 15 pages, 11 figures. Title changed and Introduction rewritten. Accepted for publication in Physical Review

Real-World Utilization of Oral Anticancer Agents and Related Costs in Older Adults with Metastatic Renal Cell Carcinoma in the United States

BACKGROUND: Substantial racial and socioeconomic disparities in metastatic RCC (mRCC) have persisted following the introduction of targeted oral anticancer agents (OAAs). The relationship between patient characteristics and OAA access and costs that may underlie persistent disparities in mRCC outcomes have not been examined in a nationally representative patient population. METHODS: Retrospective SEER-Medicare analysis of patients diagnosed with mRCC between 2007-2015 over age 65 with Medicare part D prescription drug coverage. Associations between patient characteristics, OAA receipt, and associated costs were analyzed in the 12 months following mRCC diagnosis and adjusted to 2015 dollars. RESULTS: 2,792 patients met inclusion criteria, of which 32.4%received an OAA. Most patients received sunitinib (57%) or pazopanib (28%) as their first oral therapy. Receipt of OAA did not differ by race/ethnicity or socioeconomic indicators. Patients of advanced age (>80 years), unmarried patients, and patients residing in the Southern US were less likely to receive OAAs. The mean inflation-adjusted 30-day cost to Medicare of a patient's first OAA prescription nearly doubled from $3864 in 2007 to$7482 in 2015, while patient out-of-pocket cost decreased from $2409 to$1477. CONCLUSION: Race, ethnicity, and socioeconomic status were not associated with decreased OAA receipt in patients with mRCC; however, residing in the Southern United States was, as was marital status. Surprisingly, the cost to Medicare of an initial OAA prescription nearly doubled from 2007 to 2015, while patient out-of-pocket costs decreased substantially. Shifts in OAA costs may have significant economic implications in the era of personalized medicine

Adiabatic perturbation theory: from Landau-Zener problem to quenching through a quantum critical point

We discuss the application of the adiabatic perturbation theory to analyze the dynamics in various systems in the limit of slow parametric changes of the Hamiltonian. We first consider a two-level system and give an elementary derivation of the asymptotics of the transition probability when the tuning parameter slowly changes in the finite range. Then we apply this perturbation theory to many-particle systems with low energy spectrum characterized by quasiparticle excitations. Within this approach we derive the scaling of various quantities such as the density of generated defects, entropy and energy. We discuss the applications of this approach to a specific situation where the system crosses a quantum critical point. We also show the connection between adiabatic and sudden quenches near a quantum phase transitions and discuss the effects of quasiparticle statistics on slow and sudden quenches at finite temperatures.Comment: 20 pages, 3 figures, contribution to "Quantum Quenching, Annealing and Computation", Eds. A. Das, A. Chandra and B. K. Chakrabarti, Lect. Notes in Phys., Springer, Heidelberg (2009, to be published), reference correcte

Patterns and Predictors of Oral Anticancer Agent Use in Diverse Patients with Metastatic Renal Cell Carcinoma

PURPOSE Availability of targeted oral anticancer agents (OAAs) has transformed care for patients with metastatic renal cell carcinoma (mRCC). Our objective was to identify patterns and predictors of OAA use within 12 months after mRCC was detected to understand real-world adoption of OAAs. METHODS We used a novel, North Carolina cancer registry–linked multipayer claims data resource to examine patterns of use of five oral therapies among patients with mRCC diagnosed in 2006-2015, with claims through 2016. Patients were required to have 12 months of continuous enrollment before metastatic index date. Log-Poisson models estimated unadjusted and adjusted risk ratios (RRs) for associations between patient characteristics and OAA use. In sensitivity analyses, we used a competing risk framework to estimate adjusted risk differences in OAA use. RESULTS Our population-based study of 713 patients demonstrated low (37%) OAA use during the first year after metastatic index date among both publicly and privately insured patients, with shifting patterns of use consistent with regulatory approvals over time. Compared with patients age 18-49 years, patients age 70-74 years were half likely to use OAAs (95% confidence limit [CL], 0.34 to 0.78) and patients age 801 years were 71% less likely to use OAAs (95% CL, 0.17 to 0.50). Patients with two comorbidities (RR, 0.73; 95% CL, 0.55 to 0.98) and those with 31 comorbidities (RR, 0.68; 95% CL, 0.50 to 0.91) were less likely to receive OAA than those without comorbidities. Patients with higher frailty also had lower OAA utilization (RR, 0.67; 95% CL, 0.52 to 0.85). CONCLUSION These findings suggest a need to better understand the system-level and provider-level drivers of OAA underuse, as well as OAA adherence and associated survival

Oral Anticancer Agent (OAA) Adherence and Survival in Elderly Patients With Metastatic Renal Cell Carcinoma (mRCC)

Objective: To examine real-world adherence to oral anticancer agents (OAAs) and its association with outcomes among Medicare beneficiaries with metastatic renal cell carcinoma (mRCC). Methods: SEER-Medicare retrospective cohort study of patients with metastatic renal cell carcinoma (mRCC) who received an OAA between 2007 and 2015. We examined A) adherence and B) overall and disease-specific 2-year survival landmarked at 3 months after OAA initiation. Adherence was assessed by calculating the proportion of days covered (PDC) within 3 months of OAA initiation, with adherent use being defined as PDC > 80%. Results: A total of 905 patients met study criteria, of whom 445 patients (49.2%) were categorized as adherent to initial OAA treatment. Adjusting for clinical and demographic factors revealed decreased odds of adherence associated with living within an impoverished neighborhood (OR 0.49, CI 0.0.33 – 0.74) and out-of-pocket costs > $200 (OR 0.68, CI 0.47-.98). Adherence was associated with improved 2-year survival in univariate analysis (logrank test, P = .01) and a non-significant trend toward an association with decreased all-cause (HR 0.87, CI 0.72 – 1.05) and RCC-specific survival (HR 0.84, CI 0.69 – 1.03) in multivariable analysis. Conclusion: Local poverty levels and high out-of-pocket costs are associated with poor initial adherence to OAA therapy in Medicare beneficiaries with mRCC, which in turn, suggests a trend toward poor overall and disease-specific survival. Efforts to improve outcomes in the broader mRCC population should incorporate OAA adherence and economic factors

Multiplicity Distributions in Canonical and Microcanonical Statistical Ensembles

The aim of this paper is to introduce a new technique for calculation of observables, in particular multiplicity distributions, in various statistical ensembles at finite volume. The method is based on Fourier analysis of the grand canonical partition function. Taylor expansion of the generating function is used to separate contributions to the partition function in their power in volume. We employ Laplace's asymptotic expansion to show that any equilibrium distribution of multiplicity, charge, energy, etc. tends to a multivariate normal distribution in the thermodynamic limit. Gram-Charlier expansion allows additionally for calculation of finite volume corrections. Analytical formulas are presented for inclusion of resonance decay and finite acceptance effects directly into the system partition function. This paper consolidates and extends previously published results of current investigation into properties of statistical ensembles.Comment: 53 pages, 7 figure

Provider- and patient-level predictors of oral anticancer agent initiation and adherence in patients with metastatic renal cell carcinoma

Background: Improving oral anticancer agent (OAA) initiation and adherence is the important quality-of-care issues, particularly since one fourth of anticancer agents being developed will be administered orally. Our objective was to identify provider- and patient-level characteristics associated with OAA initiation and adherence among individuals with metastatic renal cell carcinoma (mRCC). Methods: We used state cancer registry data linked to multi-payer claims data to identify patients with mRCC diagnosed in 2004–2015. Provider data were obtained from North Carolina Health Professions Data System and the National Plan & Provider Enumeration System. We estimated risk ratios (RRs) and corresponding 95% confidence limits (CLs) using modified Poisson regression to evaluate factors associated with OAA initiation and adherence. Results: Among the 207 (out of 687) patients who initiated an OAA following mRCC diagnosis and survived 90 days, median proportion of days covered was 0.91. Patients with a modal provider specializing in hematology/medical oncology were much more likely to initiate OAAs than those seen by other specialties. Additionally, patients with a female provider were more likely to initiate OAAs than those with a male provider. Compared to patients treated by providers practicing in both urban and rural areas, patients with providers practicing solely in urban areas were more likely to initiate OAAs, after controlling for patient-level factors (RR = 1.37; 95% CL: 1.09–1.73). Medicare patients were less likely to be adherent than those with private insurance (RR = 0.61; 95% CL: 0.42–0.87). Conclusions: Our results suggest that provider- and patient-level factors influence OAA initiation in patients with mRCC but only insurance type was associated with adherence

End-of-Life Care for Patients with Metastatic Renal Cell Carcinoma in the Era of Oral Anticancer Therapy

PURPOSE:New therapies including oral anticancer agents (OAAs) have improved outcomes for patients with metastatic renal cell carcinoma (mRCC). However, little is known about the quality of end-of-life (EOL) care and systemic therapy use at EOL in patients receiving OAAs or with mRCC.METHODS:We retrospectively analyzed EOL care for decedents with mRCC in two parallel cohorts: (1) patients (RCC diagnosed 2004-2015) from the University of North Carolina's Cancer Information and Population Health Resource (CIPHR) and (2) patients (diagnosed 2007-2015) from SEER-Medicare. We assessed hospice use in the last 30 days of life and existing measures of poor-quality EOL care: systemic therapy, hospital admission, intensive care unit admission, and > 1 ED visit in the last 30 days of life; hospice initiation in the last 3 days of life; and in-hospital death. Associations between OAA use, patient and provider characteristics, and EOL care were examined using multivariable logistic regression.RESULTS:We identified 410 decedents in the CIPHR cohort (53.4% received OAA) and 1,508 in SEER-Medicare (43.5% received OAA). Prior OAA use was associated with increased systemic therapy in the last 30 days of life in both cohorts (CIPHR: 26.5% v 11.0%; P <.001; SEER-Medicare: 23.4% v 11.7%; P <.001), increased in-hospital death in CIPHR, and increased hospice in the last 30 days in SEER-Medicare. Older patients were less likely to receive systemic therapy or be admitted in the last 30 days or die in hospital.CONCLUSION:Patients with mRCC who received OAAs and younger patients experienced more aggressive EOL care, suggesting opportunities to optimize high-quality EOL care in these groups