Mechanics of universal horizons

Modified gravity models such as Ho\v{r}ava-Lifshitz gravity or Einstein-{\ae}ther theory violate local Lorentz invariance and therefore destroy the notion of a universal light cone. Despite this, in the infrared limit both models above possess static, spherically symmetric solutions with "universal horizons" - hypersurfaces that are causal boundaries between an interior region and asymptotic spatial infinity. In other words, there still exist black hole solutions. We construct a Smarr formula (the relationship between the total energy of the spacetime and the area of the horizon) for such a horizon in Einstein-{\ae}ther theory. We further show that a slightly modified first law of black hole mechanics still holds with the relevant area now a cross-section of the universal horizon. We construct new analytic solutions for certain Einstein-{\ae}ther Lagrangians and illustrate how our results work in these exact cases. Our results suggest that holography may be extended to these theories despite the very different causal structure as long as the universal horizon remains the unique causal boundary when matter fields are added.Comment: Minor clarifications. References update

6. The 1960s

From David Moore – “I served as dean of the ILR School during the 1960s. This was a period that started in relative tranquility and ended in tumultuous disarray with students demonstrating, administrators trying to maintain control, and faculty worrying about traditional academic freedom and values.” Includes: Remembrances of Things Past – 1963-71; Creation of the Public Employment Relations Board; and Alumni Perspectives

Strains for identifying and studying individual vegetative (heterokaryon) incompatibility loci in Neurospora crassa

Genetic and molecular studies of vegetative incompatibility are proceeding in several Neurospora labs. The purpose of this note is to present an expanded list of strains in the Fungal Genetics Stock Center that are potentially useful when partial diploids are employed to identify different alleles at any of the 11 known het loci of N. crassa. Some of the strains are newly deposited in FGSC. Others have previously been listed under other categories in the stock list

David Dexter Perkins (1919-2007)

Obituary of David Dexter Perkin

Followup to Columbia Investigation: Reinforced Carbon/Carbon From the Breach Location in the Wing Leading Edge Studied

Initial estimates on the temperature and conditions of the breach in the Space Shuttle Columbia's wing focused on analyses of the slag deposits. These deposits are complex mixtures of the reinforced carbon/carbon (RCC) constituents, insulation material, and wing structural materials. Identification of melted/solidified Cerachrome insulation (Thermal Ceramics, Inc., Augusta, GA) indicated that the temperatures at the breach had exceeded 1760 C

Substitutional and Interstitial Diffusion in alpha2-Ti3Al(O)

The reaction between Al2O3 and alpha2-Ti3Al was studied with a series of Al2O3/alpha2-Ti3Al multiphase diffusion couples annealed at 900, 1000 and 1100 C. The diffusion-paths were found to strongly depend on alpha2- Ti3Al(O) composition. For alloys with low oxygen concentrations the reaction involved the reduction of Al2O3, the formation of a gamma-TiAl reaction-layer and diffusion of Al and O into the alpha2-Ti3Al substrate. Measured concentration profiles across the interaction-zone showed "up-hill" diffusion of O in alpha2-Ti3Al(O) indicating a significant thermodynamic interaction between O and Al, Ti or both. Diffusion coefficients for the interstitial O in alpha2-Ti3Al(O) were determined independently from the interdiffusion of Ti and Al on the substitutional lattice. Diffusion coefficients are reported for alpha2-Ti3Al(O) as well as gamma-TiAl. Interpretation of the results were aided with the subsequent measurement of the activities of Al, Ti and O in alpha 2-Ti3Al(O) by Knudsen effusion-cell mass spectrometry

Public Health Department Accreditation in Nebraska

https://digitalcommons.unmc.edu/coph_policy_reports/1023/thumbnail.jp

Generally covariant model of a scalar field with high frequency dispersion and the cosmological horizon problem

Short distance structure of spacetime may show up in the form of high freqency dispersion. Although such dispersion is not locally Lorentz invariant, we show in a scalar field model how it can nevertheless be incorporated into a generally covariant metric theory of gravity provided the locally preferred frame is dynamical. We evaluate the resulting energy-momentum tensor and compute its expectation value for a quantum field in a thermal state. The equation of state differs at high temperatures from the usual one, but not by enough to impact the problems of a hot big bang cosmology. We show that a superluminal dispersion relation can solve the horizon problem via superluminal equilibration, however it cannot do so while remaining outside the Planck regime unless the dispersion relation is artificially chosen to have a rather steep dependence on wavevector.Comment: 4 pages, 1 figure; New section added with discussion of solution to the cosmological horizon problem using superluminal dispersion, title changed to reflect new content, various additional minor change

Effectiveness and Challenges for Implementing Quality Improvement Activities in Nebraska’s Local Health Departments

What is already known on this topic? Although the implementation strategies and effectiveness of quality improvement (QI) activities have been examined extensively for many industries, including the health care sector, very few studies have focused on QI activities in the public health context. What is added by this report? The study results indicated that Nebraska’s LHDs still face significant barriers for QI implementation, including low capacity, knowledge gaps, inadequate resources, and low institutional QI maturity. What are the implications for public health practice/policy/research? Policy makers and LHDs should provide QI training and external QI expertise to LHD staff and better integrate QI strategies into LHDs’ organizational culture and structure. Given the great complexity of QI methodologies, it may be helpful for LHDs to start their QI efforts by adopting and implementing relatively simple QI techniques and strategies, such as the PDSA approach, which some Nebraska LHDs (i.e., early adopters) have found to be effective, based on our qualitative research results