Hospital and Physician Capacity Update

Offers an alternative view of healthcare costs by examining trends in hospital capacity and healthcare labor across regions. Outlines how effective management of healthcare capacity would enable affordable quality care that meets patient needs and wants

Diffusive Migration of Low-Mass Proto-planets in Turbulent Disks

Torque fluctuations due to magnetorotational turbulence in proto-planetary disks may greatly influence the migration patterns and survival probabilities of nascent planets. Provided that the turbulence is a stationary stochastic process with finite amplitude and correlation time, the resulting diffusive migration can be described with a Fokker-Planck equation, which we reduce to an advection-diffusion equation. We calibrate the coefficients with existing turbulent-disk simulations and mean-migration estimates, and solve the equation both analytically and numerically. Diffusion tends to dominate over advection for planets of low-mass and those in the outer regions of proto-planetary disks, whether they are described by the Minimum Mass Solar Nebula (MMSN) or by T-Tauri alpha disks. Diffusion systematically reduces the lifetime of most planets, yet it allows a declining fraction of them to survive for extended periods of time at large radii. Mean planet lifetimes can even be formally infinite (e.g. in an infinite steady MMSN), though median lifetimes are always finite. Surviving planets may linger near specific radii where the combined effects of advection and diffusion are minimized, or at large radii, depending on model specifics. The stochastic nature of migration in turbulent disks challenges deterministic planet formation scenarios and suggests instead that a wide variety of planetary outcomes are possible from similar initial conditions. This would contribute to the diversity of (extrasolar) planetary systems.Comment: 31 pages, 7 figures, accepted for publication in Ap

Kristen S. Living Memoirs Interview

Kristen shared her time as a house parent and caretaker at Familia Feliz, an orphanage in Rurrenbaque, Bolivia. She shared about a traumatic experience she had during her childhood and how this shaped her professional interests. Kristen also discussed the difficult nature of her mission placement and her loving approach with the children she encountered. Bolivia is a land-locked country in South America, with one-third of the country consisting of the Andes mountains. The primary ethnic groups in Bolivia consist of indigenous groups (like the Aymara, Quechua, and Guaraní), Mestizos (or those of mixed ethnicity), and those of Spanish-European descent, and 36 indigenous languages are named as official Bolivian languages along with Spanish. Bolivia is known for its wildlife and expansive salt flats. Arnade, Charles W. and McFarren, Peter J.. Bolivia . Encyclopedia Britannica, 9 Nov. 2023, https://www.britannica.com/place/Bolivia. Accessed 15 November 2023

Merlin Phosphorylation by p21-activated Kinase 2 and Effects of Phosphorylation on Merlin Localization

The Nf2 tumor suppressor gene product merlin is related to the membrane-cytoskeleton linker proteins of the band 4.1 superfamily, including ezrin, radixin, and moesin (ERMs). Merlin is regulated by phosphorylation in a Rac/cdc42-dependent fashion. We report that the phosphorylation of merlin at serine 518 is induced by the p21-activated kinase PAK2. This is demonstrated by biochemical fractionation, use of active and dominant-negative mutants of PAK2, and immunodepletion. By using wild-type and mutated forms of merlin and phospho-directed antibodies, we show that phosphorylation of merlin at serine 518 leads to dramatic protein relocalization. Neurofibromatosis type 2 (NF2)1 is an inherited disorder characterized by the development of Schwann cell tumors of the eighth cranial nerve. Mutations and loss of heterozygosity of theNF2 gene have been detected in NF2 patients and in various sporadic tumors, including schwannomas, meningiomas, and ependymomas (1). In further support of a role for NF2 in tumor suppression, mice heterozygous for an Nf2 mutation are predisposed to a wide variety of tumors with high metastatic potential (2). In a separate model in which Nf2 is inactivated specifically in Schwann cells, mice develop schwannomas and Schwann cell hyperplasia (3). The longest and predominant splice form of the Nf2gene codes for a 595-amino acid protein highly similar to the band 4.1 family of proteins. It is most closely related to the ERM proteins,moesin, ezrin, and radixin. The ERM proteins are thought to function as cell membrane-cytoskeleton linkers and are localized to cortical actin structures near the plasma membrane such as microvilli, membrane ruffles, and lamellipodia (4, 5). Likewise, merlin is localized to cortical actin structures, in patterns that partially overlap with the ERMs (1). It has been proposed that intramolecular binding of the N-terminal and C-terminal domains conformationally regulates the ERM proteins by masking binding sites for interacting proteins. The ERMs can also form homodimers and heterodimers, among themselves and with merlin, adding an additional level of complexity to the regulation of these proteins (6). The recently solved crystal structure of the moesin N/C-terminal complex strengthens this model of conformational regulation (7). Given the sequence and, most likely, structural similarities of merlin to the ERM proteins, it is possible that merlin itself could be regulated in a similar fashion. Recent studies (8, 9) have implicated additional factors in the regulation of the ERMs, including phospholipids and phosphorylation. Previous work from our group and others (10, 11) has shown that merlin is differentially phosphorylated as well and that merlin protein levels are affected by growth conditions such as cell confluency, loss of adhesion, or serum deprivation. Merlin is found in an hypophosphorylated form when the combination of cellular and environmental conditions are growth-inhibitory (10). ERMs can be phosphorylated by Rho kinase, and this phosphorylation can affect intramolecular association and cellular localization. Phosphorylation and/or phospholipids may promote the transition of the proteins to an active form by “opening” intra- and intermolecular associations. These active monomers can then bind to other interacting proteins and the actin cytoskeleton and induce actin-rich membrane projections (5,8, 12, 13). The induction of merlin phosphorylation by activated alleles of the Rho family GTPases has also been examined. Interestingly, although activated Rho did not induce noticeable phosphorylation of merlin, activated forms of Rac and cdc42 did. The site of Rac-induced phosphorylation was determined to be a serine at position 518; mutation of serine 518 results in reduced basal phosphorylation and eliminated Rac-induced phosphorylation (11). Although Rac and cdc42 are implicated in the regulation of many pathways, they are most associated with regulation of cytoskeleton reorganization and gene expression (for recent reviews see Refs.14-16). In light of the data demonstrating that activated Rac/cdc42 leads to phosphorylation and possible inactivation of merlin, the elucidation of the responsible effector pathways and their effects on merlin function are of major importance. Understanding this regulation of merlin could lead to a more complete appreciation of the effects of merlin loss in tumors

Method Assessment for Microalgae Quantification in Wastewater Treatment and Biofuel Production

There is growing interest in the use of microalgae for wastewater treatment and biofuel production. However, there is not yet a reliable, user-friendly method of quantifying the biomass and lipid production of a large sample of algae. This study aims to establish and validate new methods for green microalgae quantification using the Microplate reader and the Coulter Counter. Chlorella vulgaris was chosen as the ‘ideal’ algal species for wastewater treatment and biofuel production due to its structure, lipid production, and pollution removal ability. Three traditional quantification methods -- microscope cell count, lipid separation, and chlorophyll extraction -- were compared to the Microplate and Coulter methods based on the required time, volume of sample, and additional chemical inputs, as well as accuracy of results (via standard deviation and r2 values). It was found that the Microplate reader was much more accurate than the traditional methods and that both of the modern methods required significantly less time and smaller sample volumes than the cumbersome traditional methods. Many industries stand to benefit from these shorter, safer, and more accurate methods of quantifying microalgae