Ion friction at small values of the Coulomb logarithm

Transport properties of high-energy-density plasmas are influenced by the ion collision rate. Traditionally, this rate involves the Coulomb logarithm, $\ln\Lambda$. Typical values of $\ln\Lambda$ are \approx 10~\mbox{to}~20 in kinetic theories where transport properties are dominated by weak-scattering events caused by long-range forces. The validity of these theories breaks down for strongly-coupled plasmas, when $\ln\Lambda$ is of order one. We present measurements and simulations of collision data in strongly-coupled plasmas when $\ln\Lambda$ is small. Experiments are carried out in the first dual-species ultracold neutral plasma (UNP), using Ca$^+$ and Yb$^+$ ions. We find strong collisional coupling between the different ion species in the bulk of the plasma. We simulate the plasma using a two-species fluid code that includes Coulomb logarithms derived from either a screened Coulomb potential or a the potential of mean force. We find generally good agreement between the experimental measurements and the simulations. With some improvements, the mixed Ca$^+$ and Yb$^+$ dual-species UNP will be a promising platform for testing theoretical expressions for $\ln\Lambda$ and collision cross-sections from kinetic theories through measurements of energy relaxation, stopping power, two-stream instabilities, and the evolution of sculpted distribution functions in an idealized environment in which the initial temperatures, densities, and charge states are accurately known.Comment: 8 pages, 4 figures, 75 reference

Age and Prostate-Specific Antigen Level Prior to Diagnosis Predict Risk of Death from Prostate Cancer.

A single early prostate-specific antigen (PSA) level has been correlated with a higher likelihood of prostate cancer diagnosis and death in younger men. PSA testing in older men has been considered of limited utility. We evaluated prostate cancer death in relation to age and PSA level immediately prior to prostate cancer diagnosis. Using the Veterans Affairs database, we identified 230,081 men aged 50-89 years diagnosed with prostate cancer and at least one prior PSA test between 1999 and 2009. Prostate cancer-specific death over time was calculated for patients stratified by age group (e.g., 50-59 years, through 80-89 years) and PSA range at diagnosis (10 ranges) using Kaplan-Meier methods. Risk of 10-year prostate cancer mortality across age and PSA was compared using log-rank tests with a Bonferroni adjustment for multiple testing. 10.5% of men diagnosed with prostate cancer died of cancer during the 10-year study period (mean follow-up = 3.7 years). Higher PSA values prior to diagnosis predict a higher risk of death in all age groups (p < 0.0001). Within the same PSA range, older age groups are at increased risk for death from prostate cancer (p < 0.0001). For PSA of 7-10 ng/mL, cancer-specific death, 10 years after diagnosis, increased from 7% for age 50-59 years to 51% for age 80-89 years. Men older than 70 years are more likely to die of prostate cancer at any PSA level than younger men, suggesting prostate cancer remains a significant problem among older men (even those aged 80+) and deserves additional study

Endoplasmic Reticulum Stress is Transmissible among Cells of the Central Nervous System

Improper protein folding and trafficking are common pathological events observed in various cell types in neurodegenerative diseases. If the protein quality control mechanisms of the endoplasmic reticulum (ER) fail to re-establish proteostasis, misfolded proteins accumulate within the lumen of the ER and perturb normal cellular processes. While low-level stimulation of the unfolded protein response (UPR) is considered a beneficial physiological response to transient protein misfolding stress, or ER stress, sustained UPR activation resulting from prolonged ER stress can promote neurotoxicity. The cell-autonomous mechanisms of the UPR have been extensively characterized in the context of neuropathology. Nevertheless, there still remain unanswered questions regarding the cell-extrinsic role of the UPR under normal physiology, and how this mechanism is compromised in diseased states. To address this, we evaluated whether transferring conditioned media from ER stressed astrocytes to different cell types could modulate their functional characteristics. Our results indicate that ER stressed astrocytes secrete a mediator(s) which regulates both inflammatory and ER stress responses in other astrocytes and neurons in vitro. Initial exposure to this stress factor(s) confers resistance against subsequent ER stress to neurons by engaging the adaptive signals of the neuronal UPR. However, persistent exposure to this unidentified mediator(s) suppresses the initial protective effect and becomes cytotoxic. Overall, these findings provide insight into the cell-nonautonomous influence of ER stress on cells of the central nervous system. Further understanding the molecular mechanisms underlying this mode of intercellular communication would present novel therapeutic opportunities to treat neurodegenerative diseases

The development of an analytical technique to facilitate the understandding and comparison of merchandise materials handling systems

This paper attempted to accomplish an analytical technique to facilitate understanding and comparison of warehouse merchandise distribution systems and to test the technique by analyzing the distribution system of a grocery warehouse

The use of interpretive phenomenological analysis in couple and family therapy research

This article proposes a research methodology that is newer to the field of couple and family therapy research called Interpretive Phenomenological Analysis (IPA). Researchers exploring couple and family therapy research continue to establish the efficacy of couple and family interventions in a context that favors a positivist view of phenomena. This research continues to be critical for establishing the role of couple and family therapy in the field of mental health as well as further clarifying which interventions are best for specific clinical issues and when. IPA offers researchers the opportunity to explore how couples and families make meaning of their experiences from an intersubjective perspective. Meaning making is central to understanding couples and families as well as part of the many clinical approaches to working with couples and families. Despite the importance of meaning, few research methodologies allow for this central concept in couple and family therapy to be the focus of exploration. The following article outlines one such methodology and the possible use of IPA in couple and family therapy research

Ion Friction at Small Values of the Coulomb Logarithm

We create a dual-species ultracold neutral plasma (UNP) by photo-ionizing Yb and Ca atoms in a dual-species magneto-optical trap. Unlike single-species UNP expansion, these plasmas are well outside of the collisionless (Vlasov) approximation. We observe the mutual interaction of the Yb and Ca ions by measuring the velocity distribution for each ion species separately. We model the expansion using a fluid code including ion-ion friction and compare with experimental results to obtain a value of the Coulomb logarithm of Λ= 0.04