Field-Induced Breakup of Emulsion Droplets Stabilized by Colloidal Particles

We simulate the response of a particle-stabilized emulsion droplet in an external force field, such as gravity, acting equally on all $N$ particles. We show that the field strength required for breakup (at fixed initial area fraction) decreases markedly with droplet size, because the forces act cumulatively, not individually, to detach the interfacial particles. The breakup mode involves the collective destabilization of a solidified particle raft occupying the lower part of the droplet, leading to a critical force per particle that scales approximately as $N^{-1/2}$.Comment: 4 pages, plus 3 pages of supplementary materia

Emerging role of the KCNT1 Slack channel in intellectual disability

The sodium-activated potassium KNa channels Slack and Slick are encoded by KCNT1 and KCNT2, respectively. These channels are found in neurons throughout the brain, and are responsible for a delayed outward current termed IKNa. These currents integrate into shaping neuronal excitability, as well as adaptation in response to maintained stimulation. Abnormal Slack channel activity may play a role in Fragile X syndrome, the most common cause for intellectual disability and inherited autism. Slack channels interact directly with the Fragile X Mental Retardation protein (FMRP) and IKNa is reduced in animal models of Fragile X syndrome that lack FMRP. Human Slack mutations that alter channel activity can also lead to intellectual disability, as has been found for several childhood epileptic disorders. Ongoing research is elucidating the relationship between mutant Slack channel activity, development of early onset epilepsies and intellectual impairment. This review describes the emerging role of Slack channels in intellectual disability, coupled with an overview of the physiological role of neuronal IKNa currents

Developing a Community of Practice for Applied Uses of Future PACE Data to Address Marine Food Security Challenges

External interaction:The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission will include a hyperspectral imaging radiometer to advance ecosystem monitoring beyond heritage retrievals of the concentration of surface chlorophyll and other traditional ocean color variables, offering potential for novel science and applications. PACE is the first NASA ocean color mission to occur under the agency's new and evolving effort to directly engage practical end users prior to satellite launch to increase adoption of this freely available data toward societal challenges. Here we describe early efforts to engage a community of practice around marine food-related resource management, business decisions, and policy analysis. Obviously one satellite cannot meet diverse end user needs at all scales and locations, but understanding downstream needs helps in the assessment of information gaps and planning how to optimize the unique strengths of PACE data in combination with the strengths of other satellite retrievals, in situ measurements, and models. Higher spectral resolution data from PACE can be fused with information from satellites with higher spatial or temporal resolution, plus other information, to enable identification and tracking of new marine biological indicators to guide sustainable management. Accounting for the needs of applied researchers as well as non-traditional users of satellite data early in the PACE mission process will ultimately serve to broaden the base of informed users and facilitate faster adoption of the most advanced science and technology toward the challenge of mitigating food insecurity

INVESTIGATIONS OF THE BIOGEOCHEMICAL AND HYDRODYNAMIC IMPACTS OF OPTICAL ATTENUATION BY COLORED DETRITAL MATTER IN AN EARTH SYSTEM MODEL

Light in the surface ocean is necessary for photosynthesis by marine algae. It is also a major source of heating. Visible light diminishes approximately exponentially with increasing depth in the upper ocean. In most of the current generation of Earth System Models used for climate projection, the vertical profile of in-water shortwave radiation is calculated as an exponentially decaying function where the attenuation coefficient is parameterized in terms of phytoplankton photosynthetic pigment (chlorophyll-a) concentration. In doing so, the attenuation of light by all other aquatic constituents is assumed to co-vary with chlorophyll-a concentration. The work in this dissertation presents a revised parameterization for the light attenuation coefficient that varies as a function of chlorophyll-a concentration and the light absorption coefficient for colored detrital matter (CDM). By separating the contribution by CDM, it is free to vary independently. Two ESM model runs were conducted: the experimental run, where the light attenuation coefficient was calculated as a function of both chlorophyll-a concentration and light absorption by CDM and the control run, where the light attenuation coefficient was calculated as a function of chlorophyll-a concentration only. The geographical distribution of light absorption by CDM was prescribed using an ocean color satellite data product using data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua Earth-observing satellite. The difference between the results of these two model runs showed increased light attenuation by CDM decreased total ocean biological productivity, increased wintertime ice formation and resulted in more extreme sea surface temperatures compared to the control run. These studies are the first global-scale investigations of the biological and hydrodynamic impacts of optical attenuation by CDM in an Earth System Model. They demonstrate the importance of accurately representing light attenuation by independently varying aquatic constituents

Impacts of Water Clarity Variability on Temperature and Biogeochemistry in the Chesapeake Bay

Estuarine water clarity depends on the concentrations of aquatic constituents, such as colored dissolved organic matter, phytoplankton, inorganic suspended solids, and detritus, which are influenced by variations in riverine inputs. These constituents directly affect temperature because when water is opaque, sunlight heats a shallower layer of the water compared to when it is clear. Despite the importance of accurately predicting temperature variability, many numerical modeling studies do not adequately account for this key process. In this study, we quantify the effect of water clarity on heating by comparing two simulations of a hydrodynamic-biogeochemical model of the Chesapeake Bay for the years 2001-2005, in which (1) water clarity is constant in space and time for the computation of solar heating, compared to (2) a simulation where water clarity varies with modeled concentrations of light-attenuating materials. In the variable water clarity simulation, the water is more opaque, particularly in the northern region of the Bay. This decrease in water clarity reduces the total heat, phytoplankton, and nitrate throughout the Bay. During the spring and summer months, surface temperatures in the northern Bay are warmer by 0.1 degrees C and bottom temperatures are colder by 0.2 degrees C in the variable light attenuation simulation. Warmer surface temperatures encourage phytoplankton growth and nutrient uptake near the head of the Bay, and fewer nutrients are transported downstream. These impacts are greater during higher river flow years, when differences in temperature, nutrients, phytoplankton, and zooplankton extend further seaward compared to other years. This study demonstrates the consequences of utilizing different light calculations for estuarine heating and biogeochemistry

Rebels with a Cause: VCU Student Emergency Fund

The project’s mission is to establish a VCU Student Emergency Fund to support the well-being of students who face financial emergencies and to increase student retention and academic success. The fund will provide financial relief to students facing sudden and unexpected financial hardships that can impact their financial stability, academic success, and ability to remain enrolled at VCU. The project will support the work of student support services personnel administering the fund by providing a campus outreach plan to those who can recognize students in financial crises and refer them to the fund\u27s administrators. The project will also support the work of development personnel who will raise money for the fund by providing a donor outreach plan

Internet Safety: Positioning VCU as a National Leader in Internet Safety

While a multitude of information from a host of sources exists on how to keep children safe on the Internet, there is not a unified effort to combine it all and get it to the right people. This is not a plan to teach college students about Internet safety. This is a proposal to begin much earlier, targeting middle-school aged children and their parents, many of whom have no idea of the dangers – and opportunities – that exist in cyberspace

The Distal Cytoplasmic Tail Of The Influenza A M2 Protein Dynamically Extends From The Membrane

The influenza A M2 protein is a multifunctional membrane-associated homotetramer that orchestrates several essential events in the viral infection cycle. The monomeric subunits of the M2 homotetramer consist of an N-terminal ectodomain, a transmembrane domain, and a C-terminal cytoplasmic domain. The transmembrane domain forms a four-helix proton channel that promotes uncoating of virions upon host cell entry. The membrane-proximal region of the C-terminal domain forms a surface-associated amphipathic helix necessary for viral budding. The structure of the remaining ~34 residues of the distal cytoplasmic tail has yet to be fully characterized despite the functional significance of this region for influenza infectivity. Here, we extend structural and dynamic studies of the poorly characterized M2 cytoplasmic tail. We used SDSL-EPR to collect site-specific information on the mobility, solvent accessibility, and conformational properties of residues 61–70 of the full-length, cell-expressed M2 protein reconstituted into liposomes. Our analysis is consistent with the predominant population of the C-terminal tail dynamically extending away from the membranes surface into the aqueous medium. These findings provide insight into the hypothesis that the C-terminal domain serves as a sensor that regulates how M2 protein participates in critical events in the viral infection cycle

A Method for generating marker-less gene deletions in multidrug-resistant Acinetobacter baumannii

10.1186/1471-2180-13-158BMC Microbiology131581-1