Super-resolution neural networks improve the spatiotemporal resolution of adaptive MRI-guided radiation therapy.

Background: Magnetic resonance imaging (MRI) offers superb non-invasive, soft tissue imaging of the human body. However, extensive data sampling requirements severely restrict the spatiotemporal resolution achievable with MRI. This limits the modality's utility in real-time guidance applications, particularly for the rapidly growing MRI-guided radiation therapy approach to cancer treatment.

Experimental comparison of linear regression and LSTM motion prediction models for MLC-tracking on an MRI-linac.

Background: Magnetic resonance imaging (MRI)-guided radiotherapy with multileaf collimator (MLC)-tracking is a promising technique for intra-fractional motion management, achieving high dose conformality without prolonging treatment times. To improve beam-target alignment, the geometric error due to system latency should be reduced by using temporal prediction.

Purpose: To experimentally compare linear regression (LR) and long-short-term memory (LSTM) motion prediction models for MLC-tracking on an MRI-linac using multiple patient-derived traces with different complexities.

Investigating the use of machine learning to generate ventilation images from CT scans.

Background: Radiotherapy treatment planning incorporating ventilation imaging can reduce the incidence of radiation-induced lung injury. The gold-standard of ventilation imaging, using nuclear medicine, has limitations with respect to availability and cost.

Purpose: An alternative type of ventilation imaging to nuclear medicine uses 4DCT (or breath-hold CT [BHCT] pair) with deformable image registration (DIR) and a ventilation metric to produce a CT ventilation image (CTVI).

Workplace discrimination for persons with hearing loss: Before and after the 2008 ADA Amendments Act.

Background: Individuals with hearing loss experience unique barriers to employment frequently documented in the areas of communication and education. The purpose of this article is to contribute to extend this inquiry to the uniqueness of workplace discrimination involving persons with hearing loss.

Objective: This study investigated differences in allegations of workplace discrimination filed by persons with hearing loss ("Hearing") compared to those filed by persons with other physical or neurological disabilities (General Disability, or "GENDIS") before and after the enactment of the 2008 Americans with Disabilities Act Amendments Act (2008 Amendments).

Parasitic plasmid-host dynamics and host competition in flowing habitats.

Competition and coexistence were examined for two bacterial species, each potentially carrying a fitness-reducing, parasitic plasmid that was vertically transmitted with possible loss through segregation. Here, the fitness reduction of hosts was due to a toxin produced by plasmid-bearing cells and inhibiting plasmid-free cells. These populations were placed in a flow reactor habitat representing an idealized mammal gut.

Sink or swim? Vertical movement and nutrient storage in phytoplankton.

A simulation model of vertically migrating phytoplankton is presented, using a Lagrangian, individual-based computational approach. Algal cells acquire and store nutrient at the bottom of the habitat, using stored nutrient to grow while in shallower waters. Stored nutrient also governs movement: cells sink when their nutrient quota falls below a threshold; otherwise they rise (or at least sink more slowly).

Complete Genome of Salmonella enterica Serovar Typhimurium T5-Like Siphophage Stitch.

Salmonellosis, caused by Salmonella, is a leading cause of food poisoning worldwide. With the continuing rise of bacterial antibiotic resistance, efforts are focused on seeking new approaches for treatment of bacterial infections, namely, bacteriophage therapy. Here, we report the complete genome of S.

An exploratory study of air emissions associated with shale gas development and production in the Barnett Shale.

Unlabelled: Information regarding air emissions from shale gas extraction and production is critically important given production is occurring in highly urbanized areas across the United States. Objectives of this exploratory study were to collect ambient air samples in residential areas within 61 m (200 feet) of shale gas extraction/production and determine whether a "fingerprint" of chemicals can be associated with shale gas activity. Statistical analyses correlating fingerprint chemicals with methane, equipment, and processes of extraction/production were performed.

Competition and allelopathy with resource storage: two resources.

Allelopathy is added to a familiar mathematical model of competition between two species for two essential resources in a chemostat environment. Both species store the resources, and each produces a toxin that induces mortality in the other species. The corresponding model without toxins displays outcomes of competitive exclusion independent of initial conditions, competitive exclusion that depends on initial conditions (bistability), and globally stable coexistence, depending on tradeoffs between competitors in growth requirements and consumption of the resources.

Ammonium treatments to suppress toxic blooms of Prymnesium parvum in a subtropical lake of semi-arid climate: results from in situ mesocosm experiments.

Prymnesium parvum is a haptophyte alga that forms toxic, fish-killing blooms in a variety of brackish coastal and inland waters. Its abundance and toxicity are suppressed by ammonium additions in laboratory cultures and aquaculture ponds. In a cove of a large reservoir (Lake Granbury, Texas, USA) with recurring, seasonal blooms of P.

Competition for one nutrient with internal storage and toxin mortality.

This study presents a mathematical model of two species competing in a chemostat for one resource that is stored internally, and who also compete through allelopathy. Each species produces a toxin to that increases mortality rate of its competitor. The two species system and its single species subsystem follow mass conservation constraints characteristic of chemostat models.

STIMULATING EFFECT OF ANABAENA SP. (CYANOBACTERIA) EXUDATE ON PRYMNESIUM PARVUM (HAPTOPHYTA)(1).

Prymnesium parvum blooms have become more frequent in the south-central United States, leading to significant ecological and economic impacts. Allelopathic effects from cyanobacteria were suggested as a mechanism that might limit the development of P. parvum blooms.

Resource storage and competition with spatial and temporal variation in resource availability.

This study addresses interspecific competition for a nutrient resource that is stored within individuals in habitats with both temporal and spatial variation. In such environments, population structure is induced by the mixture at any location of individuals with different amounts of stored nutrient, acquired elsewhere in the habitat. Focusing on phytoplankton competing for phosphorus in a partially mixed water column, an individual-based Lagrangian model is used to represent this population structure, and partial differential equations that approximate competitive dynamics are constructed by averaging over this population structure.

Competition between microorganisms for a single limiting resource with cell quota structure and spatial variation.

Microbial populations compete for nutrient resources, and the simplest mathematical models of competition neglect differences in the nutrient content of individuals. The simplest models also assume a spatially uniform habitat. Here both of these assumptions are relaxed.

Element content of Ochromonas danica: a replicated chemostat study controlling the growth rate and temperature.

Ecological stoichiometry focuses on the balance between multiple nutrient elements in resources and in consumers of those resources. The major consumers of bacteria in aquatic food webs are heterotrophic and mixotrophic nanoflagellates. Despite the importance of this consumer-resource interaction to understanding nutrient dynamics in the aquatic food web, few data are available addressing the element stoichiometry of flagellate consumers.

Element stoichiometry of a mixotrophic protist grown under varying resource conditions.

The balance of essential elements (e.g. carbon [C], nitrogen [N], and phosphorus [P]) between consumers and their resources influences not only the growth and reproduction of the consumers but also the nutrients they regenerate.

Coexistence of mixotrophs, autotrophs, and heterotrophs in planktonic microbial communities.

We examine what circumstances allow the coexistence of microorganisms following different nutritional strategies, using a mathematical model. This model incorporates four nutritional types commonly found in planktonic ecosystems: (1) heterotrophic bacteria that consume dissolved organic matter and are prey to some of the other organisms; (2) heterotrophic zooflagellates that depend entirely on bacterial prey; (3) phototrophic algae that depend only on light and inorganic nutrients, and (4) mixotrophs that photosynthesize, take up inorganic nutrients, and consume bacterial prey. Mixotrophs are characterized by a parameter representing proportional mixing of phototrophic and heterotrophic nutritional strategies.

A mechanistic explanation for pH-dependent ambient aquatic toxicity of Prymnesium parvum carter.

The harmful algal bloom species Prymnesium parvum has caused millions of dollars in damage to fisheries around the world. These fish kills have been attributed to P. parvum releasing a mixture of toxins in the water.

Competition and coexistence in flowing habitats with a hydraulic storage zone.

This paper examines a model of a flowing water habitat with a hydraulic storage zone in which no flow occurs. In this habitat, one or two microbial populations grow while consuming a single nutrient resource. Conditions for persistence of one population and coexistence of two competing populations are derived from eigenvalue problems, the theory of bifurcation and the theory of monotone dynamical systems.

Dynamics and nutritional ecology of a nanoflagellate preying upon bacteria.

Ingestion and growth rates of the nanoflagellate predator Ochromonas danica feeding on the bacterium Pseudomonas fluorescens were quantified in laboratory cultures. Bacterial prey were grown under four nutritional conditions with respect to macronutrient elements: C-limited, N-limited, P-limited, and balanced. Ingestion and growth rates were saturating functions of prey abundance when preying upon nutritionally balanced, C-limited, and P-limited bacteria but were unimodal functions of abundance when preying on N-limited bacteria.

Is storage an adaptation to spatial variation in resource availability?

When individuals store resources acquired while moving through a spatially variable habitat, a form of population structure arises. The theoretical consequences of this process for resource competition are studied for phytoplankton species consuming a single nutrient resource, using a Lagrangian modeling approach. Each competitor population is divided into many subpopulations that move through two model habitats with gradients in nutrient availability: an unstirred chemostat and a partially mixed water column.

Laboratory tests of ammonium and barley straw extract as agents to suppress abundance of the harmful alga Prymnesium parvum and its toxicity to fish.

Prymnesium parvum is a harmful alga whose blooms can cause fish kills in brackish waters. Two potential suppressants of this alga were tested, ammonium and barley straw extract (BSE), at temperatures of 10, 20 and 30 degrees C. Laboratory batch cultures were grown for 3 weeks at each temperature, with weekly doses of ammonium or BSE at either low or high levels, or a no-dose control treatment.

Prey food quality affects flagellate ingestion rates.

Flagellate feeding efficiency appears to depend on morphological characteristics of prey such as cell size and motility, as well as on other characteristics such as digestibility and cell surface characteristics. Bacteria of varying morphological characteristics (cell size) and mineral nutrient characteristics or food quality (as determined by the C:N:P ratio) were obtained by growing Pseudomonas fluorescens in chemostats at four dilution rates (0.03, 0.

Phytoplankton species richness scales consistently from laboratory microcosms to the world's oceans.

Species-area relationships have been observed for virtually all major groups of macroorganisms that have been studied to date but have not been explored for microscopic phytoplankton algae, which are the dominant producers in many freshwater and marine ecosystems. Our analyses of data from 142 different natural ponds, lakes, and oceans and 239 experimental ecosystems reveal a strong species-area relationship with an exponent that is invariant across ecosystems that span >15 orders of magnitude in spatial extent. A striking result is that the species-area relationship derived from small-scale experimental studies correctly scales up to natural aquatic ecosystems.