Does Service Bundling Reduce Churn?

We examine whether bundling in telecommunications services reduces churn using a series of large, independent cross sections of household decisions. To identify the effect of bundling, we construct a pseudo-panel dataset and utilize a linear, dynamic panel-data model, supplemented by nearest-neighbor matching. We find bundling does reduce churn for all three "triple-play" services. However, the effect is only "visible" during times of turbulent demand. We also find evidence that broadband was substituting for pay television in 2009. This analysis highlights that bundling helps with customer retention in service industries, and may play an important role in preserving contracting markets.Bundle, Service, Churn, Triple Play, Telecommunications, Cable, Broadband, Telephone, Screen

Development of a Novel Helmet Support Assembly for NASA Orion Crew Survival Suit

Orion Spacecraft water landing environments have necessitated the design and testing of a novel Helmet Support Assembly (HSA) as part of the NASA Orion Crew Survival Systems (OCSS) launch and re-entry spacesuit. A series of development sled tests using 5 th female, 50th male, and 95th male Hybrid III Anthropometric Test Devices (ATDs) simulated worst case water landings and identified the need for an integrated suit countermeasure to control the helmet during dynamic loading. Initial prototype countermeasures rigidly restrained the helmet keeping the helmet in place as desired, but led to large force and moment transmission to the upper neck. Further development led to a flexible HSA which used high-strength steel wire contoured to the size-matched ATD thorax and attached to both the front and rear of the neck ring. The selected wire diameter and contoured shape provided some ability to flex under the expected worst-case dynamic loads. The existing shoulder harness was used to restrain the helmet motion during eyeballs out/down loading while also attempting to prevent head-to-helmet contact in eyeballs down spinal-axis loading. A new small prototype helmet was also developed and tested for the 5th and 50th ATDs with both HSA devices. Dynamic impact tests were conducted on the HIA (Horizontal Impulse Accelerator) at Wright Patterson Air Force Base (WPAFB) under simulated off-nominal landing conditions using a representative Orion seat and 5-point harness. For each ATD size, peak Neck Injury Criteria (Nij) were compared to equivalent sled tests with an unsuited ATD configuration. Adding a helmet without attempting to control motion increased peak Nij values for all ATD sizes. The use of the rigid countermeasure showed decreased peak Nij results for the 5th female, but increased peak Nij values for both 50th configurations and the 95th male ATDs. By comparison, the flexible HSA showed reduced peak Nij values for all ATD sizes. Overall, this series of dynamic impact tests identified a risk of increased crew neck loading when under- or over-restraining the helmet during simulated Orion water landings and also demonstrated an effective strategy to mitigate those loads with a compliant HSA design

Balancing nutrition management and the role of dietitians in eating disorder treatment

The symptoms of starvation and dietary restriction are often the subject of targeted intervention in evidence-based treatments across eating disorder diagnoses and treatment models. Despite the level of attention given to these symptoms of clinical malnutrition, they are often treated by health professionals with no nutritional qualifications and in a non-clinical manner in the outpatient setting, with dietitians having no defined role in manualised treatment models. Recently the Australia & New Zealand Academy for Eating Disorders (ANZAED) published practice and training standards for dietitians to help characterise their role in eating disorder treatment. Since malnutrition, secondary to dietary restriction, is a clinically significant nutritional diagnosis that co-occurs in eating disorder presentations, this commentary proposes that dietitians are ideally-positioned to assess and advise on the clinical aspects of malnutrition as a key member of the multidisciplinary team. Food is a central focus in eating disorder treatment, suggesting that nutritional care needs to be addressed by a dietitian alongside the psychological aspects of care that are addressed by a mental health professional

Quantifying the ki-67 heterogeneity profile in prostate cancer.

BackgroundKi-67 is a robust predictive/prognostic marker in prostate cancer; however, tumor heterogeneity in prostate biopsy samples is not well studied.MethodsUsing an MRI/US fusion device, biopsy cores were obtained systematically and by targeting when indicated by MRI. Prostate cores containing cancer from 77 consecutive men were analyzed. The highest Ki-67 was used to determine interprostatic variation. Ki-67 range (highest minus lowest) was used to determine intraprostatic and intralesion variation. Apparent diffusion coefficient (ADC) values were evaluated in relation to Ki-67.ResultsInterprostatic Ki-67 mean ± standard deviation (SD) values for NCCN low (L), intermediate (I), and high (H) risk patients were 5.1 ± 3.8%, 7.4 ± 6.8%, and 12.0 ± 12.4% (ANOVA P = 0.013). Intraprostatic mean ± SD Ki-67 ranges in L, I, and H risk patients were 2.6 ± 3.6%, 5.3 ± 6.8%, and 10.9 ± 12.3% (ANOVA P = 0.027). Intralesion mean ± SD Ki-67 ranges in L, I, and H risk patients were 1.1 ± 0.9%, 5.2 ± 7.9%, and 8.1 ± 10.8% (ANOVA P = 0.22). ADC values at Ki-67 > and <7.1% were 860 ± 203 and 1036 ± 217, respectively (P = 0.0029).ConclusionsHigh risk patients have significantly higher inter- and intraprostatic Ki-67 heterogeneity. This needs to be considered when utilizing Ki-67 clinically

Freeze-drying Silica Based Aerogels Using Cryoprotectants and Eutectic Solvent Mixtures

Silica based aerogels have unique properties, including good thermal insulation and convective inhibition. A sol-gel process can be used to produce semi-opaque, monolithic gels, which can then be dried to produce aerogels. Multiple drying methods are available industrially, however, these methods require high temperatures and pressures, specialized equipment, and are time consuming. This project aims to experimentally study the possibility of a new method for drying wet gels through a freeze-drying process, with the use of cryoprotectants, eutectics, and polymers to inhibit and control ice formation and growth during drying. Silica wet gels were produced using tetraethylorthosilicate (TEOS), ethanol, water, and hydrochloric acid/ammonia hydroxide. After gelation the gels were subjected to solvent exchanges with varying concentrations of cryoprotectants, eutectics, polymers and combinations of the three. A customized freeze-dryer was used to obtain silica aerogels from wet gels, with monolithicity and porosity of the resulting aerogel measured by SEM and BET. The results indicated that the addition of cryoprotectants, eutectics, and polymers yielded monolithic foams which were structurally stable and had measurable porosity and surface area. Using the processes developed in this work would allow for simpler, more cost effective methods for drying wet gels to be developed; these methods could be used to produce freeze-dried aerogels with better properties and have potential for industrial implementation

Microstructurally-based constitutive models of cytoskeletal networks for simulation of the biomechanical response of biological cells

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (v. 2, p. 335-375).The elastic and viscoelastic stress-strain behavior of cytoskeletal networks, important to many cellular functions, is modeled via a microstructurally-informed continuum mechanics approach. The force-extension behavior of the individual filaments is captured with a new analytical expression of the MacKintosh worm-like chain relationship for semiflexible filaments. The filament expression is used in the Arruda-Boyce eight-chain network model to capture the 3D stress-strain behavior, quantifying the effects of isotropic network prestress and tracking microstructural stretch and orientation states during large deformations. The network model captures the initial stiffness of the network as well as the nonlinear strain stiffening observed at large stresses in shear rheological data of bundled/unbundled in vitro F-actin networks. The cytoskeletal network model has also been extended to include the internal energy based mechanical contributions at the filament and network levels from torsional crosslink deformations as well as from direct axial stretching of filaments. This enhanced model effectively captures the stress-strain behavior of F-actin networks cross-linked with two different types of actin binding proteins (filamin and streptavidin). The enhanced model is also used to evaluate the influence of the cross-links' torsional stiffness on the entropic bending configuration space of the cytoskeletal filaments. The 3D constitutive network model provides a framework for capturing time-dependent spatial diffusion of cytosol within a porous, visco hyperelastic filament network. The poroelastic behavior is coupled with the hyperelastic network behavior through a 3D biphasic theory that includes network swelling effects for finite deformations.(cont.) The mechanical response of the cytoskeletal network due to the localized swelling is captured by employing multiplicative decomposition of mechanical and swelling stretches. Nonlinear shear viscoelasticity is also included to create a 3D network model capable of capturing the time-dependent response of cytoskeletal networks on short and long time scales. The model captures the nonlinear time dependent behavior of in vitro actin-filamin and actin-avidin networks observed in shear rheological experiments. The constitutive models are evaluated in a finite element model with a cellular geometry (including membrane and nucleus submodels) and the ability to spatially vary network properties throughout the cell.by Jeffrey Shane Palmer.Ph.D