1,455 research outputs found
SPLINE MODELS FOR ESTIMATING HEAT STRESS THRESHOLDS IN CATTLE
Studies of the relationship between animal body temperature and air temperature suggest body temperature is essentially unresponsive until a threshold is reached, then it responds dramatically to increasing air temperature. The goal is to estimate the threshold between the thermoneutral plateau and the beginning of the heat stress challenge. One approach is to fit a polynomial to estimate the knot position and use spline functions to perform linear least squares piecewise polynomial fitting. Another alternative is to use nonlinear regression to estimate the knot or an inflection point of a nonlinear function. In both approaches the cyclic nature of body temperature is ignored. This paper explores the use of nonlinear regression to estimate the knot position and handles the hysteresis effect resulting from the cyclic nature of body temperature. Models are fit to data collected from cattle in chambers subjected to semicontrolled sinusoidal air temperature at the University of Missouri-Columbia Animal Science department and a procedure for estimating the heat stress threshold is proposed
Examining c-di-GMP and possible quorum sensing regulation in Pseudomonas fluorescens SBW25:links between intra and inter-cellular regulation benefits community cooperative activities such as biofilm formation
Bacterial success in colonizing complex environments requires individual response to micro-scale conditions as well as community-level cooperation to produce large-scale structures such as biofilms. Connecting individual and community responses could be achieved by linking the intracellular sensory and regulatory systems mediated by bis-(3β²-5β²)-cyclic dimeric guanosine monophosphate (c-di-GMP) and other compounds of individuals with intercellular quorum sensing (QS) regulation controlling populations. There is growing evidence to suggest that biofilm formation by many pseudomonads is regulated by both intra and intercellular systems, though in the case of the model Pseudomonas fluorescens SBW25 Wrinkly Spreader in which mutations increasing c-di-GMP levels result in the production of a robust cellulose-based air-liquid interface biofilm, no evidence for the involvement of QS regulation has been reported. However, our recent review of the P. fluorescens SBW25 genome has identified a potential QS regulatory pathway and other QSβassociated genes linked to c-di-GMP homeostasis, and QS signal molecules have also been identified in culture supernatants. These findings suggest a possible link between c-di-GMP and QS regulation in P. fluorescens SBW25 which might allow a more sophisticated and responsive control of cellulose production and biofilm formation when colonising the soil and plant-associated environments P. fluorescens SBW25 normally inhabits.ΠΠ½Π°Π»ΠΈΠ· Ρ-Π΄ΠΈ-ΠΠΠ€ ΠΈ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΠ³ΠΎ ΡΡΠ²ΡΡΠ²Π° ΠΊΠ²ΠΎΡΡΠΌΠ° Ρ Pseudomonas fluorescens SBW 25: ΡΠ²ΡΠ·Ρ ΠΌΠ΅ΠΆΠ΄Ρ Π²Π½ΡΡΡΠΈ ΠΈ ΠΌΠ΅ΠΆΠΊΠ»Π΅ΡΠΎΡΠ½ΠΎΠΉ ΡΠ΅Π³ΡΠ»ΡΡΠΈΠ΅ΠΉ ΡΠΏΠΎΡΠΎΠ±ΡΡΠ²ΡΠ΅Ρ ΠΊΠΎΠΎΠΏΠ΅ΡΠ°ΡΠΈΠ²Π½ΠΎΠΌΡ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ Π² ΡΠΎΠΎΠ±ΡΠ΅ΡΡΠ²Π΅ ΠΈ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π±ΠΈΠΎΠΏΠ»ΡΠ½ΠΊΠΈΠ£ΡΠΏΠ΅ΡΠ½ΠΎΡΡΡ Π±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ ΠΊΠΎΠ»ΠΎΠ½ΠΈΠ·Π°ΡΠΈΠΈ ΡΠ»ΠΎΠΆΠ½ΡΡ
ΡΠΊΠΎΠ½ΠΈΡ ΡΡΠ΅Π±ΡΠ΅Ρ ΠΈΠ½Π΄ΠΈΠ²ΠΈΠ΄ΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΎΡΠ²Π΅ΡΠ° Π½Π° ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΡΠ»ΠΎΠ²ΠΈΠΉ Π½Π° ΠΌΠΈΠΊΡΠΎΡΡΠΎΠ²Π½Π΅ ΡΠ°Π²Π½ΠΎ ΠΊΠ°ΠΊ ΠΈ ΠΊΠΎΠΎΠΏΠ΅ΡΠ°ΡΠΈΠΈ Π½Π° ΡΡΠΎΠ²Π½Π΅ ΡΠΎΠΎΠ±ΡΠ΅ΡΡΠ²Π° Π΄Π»Ρ ΠΏΡΠΎΠ΄ΡΠΊΡΠΈΠΈ ΡΠ°ΠΊΠΈΡ
ΠΊΡΡΠΏΠ½ΠΎ ΠΌΠ°ΡΡΡΠ°Π±Π½ΡΡ
ΡΡΡΡΠΊΡΡΡ ΠΊΠ°ΠΊ Π±ΠΈΠΎΠΏΠ»ΡΠ½ΠΊΠΈ. ΠΠΎΠΎΡΠ΄ΠΈΠ½Π°ΡΠΈΡ ΠΈΠ½Π΄ΠΈΠ²ΠΈΠ΄ΡΠ°Π»ΡΠ½ΡΡ
ΠΎΡΠ²Π΅Ρ ΠΎΠ² ΠΈ ΠΎΡΠ²Π΅ΡΠΎΠ² ΡΠΎΠΎΠ±ΡΠ΅ΡΡΠ²Π° ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ Π΄ΠΎΡΡΠΈΠ³Π½ΡΡΠ° ΠΏΡΡΠ΅ΠΌ ΡΠ²ΡΠ·ΡΠ²Π°Π½ΠΈΡ Π²Π½ΡΡΡΠΈΠΊΠ»Π΅ΡΠΎΡΠ½ΡΡ
ΡΠ΅Π½ΡΠΎΡΠ½ΡΡ
ΠΈ ΡΠ΅Π³ΡΠ»ΡΡΠΎΡΠ½ΡΡ
ΡΠΈΡΡΠ΅ΠΌ, ΠΎΠΏΠΎΡΡΠ΅Π΄ΡΠ΅ΠΌΡΡ
Π±ΠΈΡ-(3',5')-ΡΠΈΠΊΠ»ΠΈΡΠ΅ΡΠΊΠΈΠΌ Π΄ΠΈΠΌΠ΅ΡΠ½ΡΠΌ Π³ΡΠ°Π½ΠΎΠ·ΠΈΠ½ΠΌΠΎΠ½ΠΎΡΠΎΡΡΠ°ΡΠΎΠΌ (Ρ-Π΄ΠΈ-ΠΠΠ€) ΠΈ Π΄ΡΡΠ³ΠΈΠΌΠΈ ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΡΠΌΠΈ ΠΈΠ½Π΄ΠΈΠ²ΠΈΠ΄ΡΡΠΌΠΎΠ² Ρ ΠΌΠ΅ΠΆΠΊΠ»Π΅ΡΠΎΡΠ½ΠΎΠΉ ΡΠ΅Π³ΡΠ»ΡΡΠΈΠ΅ΠΉ - ΡΡΠ²ΡΡΠ²ΠΎΠΌ ΠΊΠ²ΠΎΡΡΠΌΠ° (Π§Π), ΠΊΠΎΠ½ΡΡΠΎΠ»ΠΈΡΡΡΡΠ΅ΠΌ ΠΏΠΎΠΏΡΠ»ΡΡΠΈ Ρ. ΠΠ°ΠΊΠ°ΠΏΠ»ΠΈΠ²Π°Π΅ΡΡΡ Π²ΡΡ Π±ΠΎΠ»ΡΡΠ΅ Π΄ΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΡΡΡΠ² ΡΠΎΠ³ΠΎ, ΡΡΠΎ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ Π±ΠΈΠΎΠΏΠ»Π΅Π½ΠΊΠΈ ΠΌΠ½ΠΎΠ³ΠΈΠΌΠΈ ΠΏΡΠ΅Π²Π΄ΠΎΠΌΠΎΠ½Π°Π΄Π°ΠΌΠΈ ΡΠ΅Π³ΡΠ»ΠΈΡΡΠ΅ΡΡΡ ΠΊΠ°ΠΊ Π²Π½ΡΡΡΠΈ ΠΊΠ»Π΅ΡΠΎΡΠ½ΡΠΌΠΈ, ΡΠ°ΠΊ ΠΈ ΠΌΠ΅ΠΆ ΠΊΠ»Π΅ΡΠΎΡΠ½ΡΠΌΠΈ ΡΠ΅Π³ΡΠ»ΡΡΠΎΡΠ½ΡΠΌΠΈ ΡΠΈΡΡΠ΅ΠΌΠ°ΠΌΠΈ, Ρ
ΠΎΡΡ Π² ΡΠ»ΡΡΠ°Π΅ ΠΌΠΎΠ΄Π΅Π»ΡΠ½ΠΎΠΉ Pseudomonas fluorescens SBW25 Wrinkly Spreader, Ρ ΠΊΠΎΡΠΎΡΠΎΠΉ ΠΌΡΡΠ°ΡΠΈΠΈ, ΠΏΠΎΠ²ΡΡΠ°ΡΡ ΠΈΠ΅ ΡΡΠΎΠ²Π½ΠΈ Ρ-Π΄ΠΈ-ΠΠΠ€, ΠΏΡΠΈΠ²ΠΎΠ΄ΡΡ ΠΊ ΡΠΎΠ·Π΄Π°Π½ΠΈΡ ΠΏΡΠΎΡΠ½ΠΎΠΉ ΡΠ΅Π»Π»ΡΠ»ΠΎΠ·Π½ΠΎΠΉ Π±ΠΈΠΎΠΏΠ»ΡΠ½ΠΊΠΈ Π½Π° Π³ΡΠ°Π½ΠΈΡΠ΅ ΡΠ°Π·Π΄Π΅Π»Π° ΡΠ°Π· Π²ΠΎΠ·Π΄ΡΡ
-ΠΆΠΈΠ΄ΠΊΠΎΡΡΡ, Π½Π΅ Π±ΡΠ»ΠΎ ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ΠΎ Π½ΠΈ ΠΊΠ° ΠΊΠΎΠ³ΠΎ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²Π° Π²ΠΎΠ²Π»Π΅ΡΠ΅Π½ΠΈΡ ΠΊΠ²ΠΎΡΡΠΌ-Π·Π°Π²ΠΈΡΠΈΠΌΠΎΠΉ ΡΠ΅Π³ΡΠ»ΡΡΠΈΠΈ. ΠΠ΄Π½Π°ΠΊΠΎ Π½Π°Ρ Π½Π΅Π΄Π°Π²Π½ΠΈΠΉ ΠΎΠ±Π·ΠΎΡ Π³Π΅Π½ΠΎΠΌΠ° P. fluorescens SBW25 Π²ΡΡΠ²ΠΈΠ» ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»ΡΠ½ΡΠΉ Π§Π-Π·Π°Π²ΠΈΡΠΈΠΌΡΠΉ ΡΠ΅Π³ΡΠ»ΡΡΠΎΡΠ½ΡΠΉ ΠΏΡ ΡΡ ΠΈ Π΄ΡΡΠ³ΠΈΠ΅ Π§Π-Π·Π°Π²ΠΈΡΠΈΠΌΡΠ΅ Π³Π΅Π½Ρ, ΡΠ²ΡΠ·Π°Π½Π½ΡΠ΅ Ρ Π³ΠΎΠΌΠ΅ΠΎΡΡΠ°Π·ΠΎΠΌ Ρ-Π΄ΠΈ-ΠΠΠ€, Π° ΠΌΠΎΠ»Π΅ΠΊΡΠ»Ρ Π§Π-ΡΠΈΠ³Π½Π°Π»ΠΈΠ½Π³Π° Π±ΡΠ»ΠΈ ΠΈΠ΄Π΅Π½ΡΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Ρ Π² ΠΊΡΠ»ΡΡΡΡΠ΅. ΠΡΠΈ Π΄Π°Π½Π½ΡΠ΅ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΡΡΡ ΠΎ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΠΉ ΡΠ²ΡΠ·ΠΈ ΠΌΠ΅ΠΆΠ΄Ρ Ρ-Π΄ΠΈ-ΠΠΠ€-ΡΠ΅Π³ΡΠ»ΡΡΠΈΠ΅ΠΉ ΠΈ Π§Π Ρ P. fluorescens SBW25, ΡΡΠΎ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ Π±ΠΎΠ»Π΅Π΅ ΡΠ»ΠΎΠΆΠ½ΡΠΉ ΠΈ Π³ΠΈΠ±ΠΊΠΈΠΉ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ Π½Π°Π΄ ΠΏΡΠΎΠ΄ΡΠΊΡΠΈΠ΅ΠΉ ΡΠ΅Π»Π»ΡΠ»ΠΎΠ·Ρ ΠΈ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈ Π΅ΠΌ Π±ΠΈΠΎΠΏΠ»Π΅Π½ΠΊΠΈ ΠΏΡΠΈ ΠΊΠΎΠ»ΠΎΠ½ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΠΎΡΠ² ΠΈ ΡΠΊΠΎΠ½ΠΈΡ, aΡΡΠΎΡΠΈΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
Ρ ΡΠ°ΡΡΠ΅Π½ΠΈΡΠΌ ΠΈ, - Π΅ΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠΌΠΈ ΡΡΠ΅Π΄Π°ΠΌΠΈ ΠΎΠ±ΠΈΡΠ°Π½ΠΈΡ P. fluorescens SBW25
A goal direction signal in the human entorhinal/subicular region
Being able to navigate to a safe place, such as a home or nest, is a fundamental behaviour for all complex animals. Determining the direction to such goals is a crucial first step in navigation. Surprisingly, little is known about how, or where in the brain, this 'goal direction signal' is represented. In mammals 'head-direction cells' are thought to support this process, but despite 30 years of research no evidence for a goal direction representation has been reported [1, 2]. Here we used functional magnetic resonance imaging to record neural activity while participants made goal directions judgments based on a previously learned virtual environment. We applied multivoxel pattern analysis [3-5] to this data, and found that the human entorhinal/subicular region contains a neural representation of intended goal direction. Furthermore, the neural pattern expressed for a given goal direction matched the pattern expressed when simply facing that same direction. This suggests the existence of a shared neural representation of both goal and facing direction. We argue that this reflects a mechanism based on head-direction populations that simulate future goal directions during route planning [6]. Our data further revealed that the strength of direction information predicts performance. Finally, we found a dissociation between this geocentric information in the entorhinal/subicular region and egocentric direction information in the precuneus
PROBABILISTIC MODELLING OF EARTHQUAKE OCCURRENCE: FIRST EXAMPLES OF DATA INTEGRATION WITHIN A BAYESIAN FRAMEWORK
PROBABILISTIC MODELLING OF EARTHQUAKE OCCURRENCE: FIRST EXAMPLES OF DATA INTEGRATION WITHIN A BAYESIAN FRAMEWOR
Study of diffusion weighted MRI as a predictive biomarker of response during radiotherapy for high and intermediate risk squamous cell cancer of the oropharynx: The MeRInO study
Introduction and background:
A significant proportion of patients with intermediate and high risk squamous cell cancer of the oropharynx (OPSCC) continue to relapse locally despite radical chemoradiotherapy (CRT). The toxicity of the current combination of intensified dose per fraction radiotherapy and platinum based chemotherapy limits further uniform intensification. If a predictive biomarker for outcomes from CRT can be identified during treatment then individualised and adaptive treatment strategies may be employed.
Methods/design:
The MeRInO study is a prospective observational imaging study of patients with intermediate and high risk, locally advanced OPSCC receiving radical RT or concurrent CRT Patients undergo diffusion weighted MRI prior to treatment (MRI_1) and during the third week of RT (MRI_2). Apparent diffusion coefficient (ADC) measurements will be made on each scan for previously specified target lesions (primary and lymph nodes) and change in ADC calculated. Patients will be followed up and disease status for each target lesion noted. The primary aim of the MeRInO study is to determine the threshold change in ADC from baseline to week 3 of RT that may identify the sub-group of non-responders during treatment.
Discussion:
The use of DW-MRI as a predictive biomarker during RT for SCC H&N is in its infancy but studies to date have found that response to treatment may indeed be predicted by comparison of DW-MRI carried out before and during treatment. However, previous studies have included all sub-sites and biological sub-types. Establishing ADC thresholds that predict for local failure is an essential step towards using DW-MRI to improve the therapeutic ratio in treating SCC H&N. This would be done most robustly in a specific H&N sub-site and in sub-types with similar biological behaviour. The MeRInO study will help establish these thresholds in OPSCC
USING NONLINEAR FIXED AND MIXED MODELS TO STUDY ACCLIMATION TO HEAT STRESS IN CATTLE
Researchers studying acclimation of cattle to heat stress want to know if exposure to heat stress in controlled chambers will help cattle adjust to climatic conditions in the field. The four parameter nonlinear PET model is used to study the relationship between core body temperature and ambient temperature. This model works well when cattle are challenged by heat stress but the model is less useful for thermoneutral conditions. Both proc Nlin and Nlmixed are used to compare and contrast the field parameters between the controlled and the potentially acclimated group. Simulation studies were used to compare the effectiveness of proc Nlin versus proc Nlmixed. The results are helpful, not only for researchers who study acclimation, but also for those who study sensitivity, tolerance and robustness of cattle during heat stress
Computer models of saliency alone fail to predict subjective visual attention to landmarks during observed navigation
This study aimed to understand whether or not computer models of saliency could explain landmark saliency. An online survey was conducted and participants were asked to watch videos from a spatial navigation video game (Sea Hero Quest). Participants were asked to pay attention to the environments within which the boat was moving and to rate the perceived saliency of each landmark. In addition, state-of-the-art computer saliency models were used to objectively quantify landmark saliency. No significant relationship was found between objective and subjective saliency measures. This indicates that during passive observation of an environment while being navigated, current automated models of saliency fail to predict subjective reports of visual attention to landmarks
CHARACTERIZING THERMAL HYSTERESIS IN BODY TEMPERATURE FOR A HEAT STRESSED STEER
Studies have shown that exposure of animals to a high ambient temperature environment poses serious threats to their health, performance and productivity. Above a certain threshold an animal\u27s body temperature (Tb) appears to be driven by the hot ambient temperature (Ta). For steers challenged by heat stress, the Tb-Ta relationship shows a dramatic increase in Tb per unit change of Ta and the dynamics of the Tb-Ta relationship follow a pattern which depends on whether Ta is increasing or decreasing. A delay becomes noticeable in a steerβs thermo-regulatory response to Ta when Ta is controlled to be sinusoidal in the steerβs heat stress chamber. In other words, Tb lags behind Ta. Consequently when plotted in a Tb-Ta phase diagram, a hysteresis effect appears in the form of a hysteresis loop, indicating the steer is thermally challenged. The hysteresis loop shows a rotated elliptical pattern which depends on the delay (or lag) between Tb and Ta. The angle of rotation of the hysteresis loop indicates the correlation (and lag) between Tb and Ta. The area of the elliptical hysteresis loop can be used to quantify the amount of heat stress during the period of thermal challenge. For example, results of a thermal challenge of 32Β±7oC applied to a Hereford steer showed, the delay is longer (4 hr lag) and ellipse is larger in an acute stage than in a chronic stage (3 hr lag). A greater delay (or lag) suggests more time is needed to dissipate the heat stress. This result suggests, steers in an acute stage require more energy to dissipate heat than steers in a chronic stage
Entropy and a Sub-Group of Geometric Measures of Paths Predict the Navigability of an Environment
Despite extensive research on navigation, it remains unclear which features of an environment predict how difficult it will be to navigate. We analysed 478,170 trajectories from 10,626 participants who navigated 45 virtual environments in the research app-based game Sea Hero Quest. Virtual environments were designed to vary in a range of properties such as their layout, number of goals, visibility (varying fog) and map condition. We calculated 58 spatial measures grouped into four families: task-specific metrics, space syntax configurational metrics, space syntax geometric metrics, and general geometric metrics. We used Lasso, a variable selection method, to select the most predictive measures of navigation difficulty. Geometric features such as entropy, area of navigable space, number of rings and closeness centrality of path networks were among the most significant factors determining the navigational difficulty. By contrast a range of other measures did not predict difficulty, including measures of intelligibility. Unsurprisingly, other task-specific features (e.g. number of destinations) and fog also predicted navigation difficulty. These findings have implications for the study of spatial behaviour in ecological settings, as well as predicting human movements in different settings, such as complex buildings and transport networks and may aid the design of more navigable environments
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