Water wave transmission by an array of floating disks

An experimental validation of theoretical models of transmission of regular water waves by large arrays of floating disks is presented. The experiments are conducted in a wave basin. The models are based on combined potential-flow and thin-plate theories, and the assumption of linear motions. A low-concentration array, in which disks are separated by approximately a disk diameter in equilibrium, and a high-concentration array, in which adjacent disks are almost touching in equilibrium, are used for the experiments. The proportion of incident wave energy transmitted by the disks is presented as a function of wave period, and for different wave amplitudes. Results indicate that the models predict wave energy transmission accurately for small-amplitude waves and low-concentration arrays. Discrepancies for large-amplitude waves and high-concentration arrays are attributed to wave overwash of the disks and collisions between disks. Validation of model predictions of rigid-body motions of a solitary disk are also presented

Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower?

The coupled numerical weather model WRF-SPA (Weather Research and Forecasting model and Soil-Plant-Atmosphere model) has been used to investigate a 3 yr time series of observed atmospheric CO₂ concentrations from a tall tower in Scotland, UK. Ecosystem-specific tracers of net CO₂ uptake and net CO₂ release were used to investigate the contributions to the tower signal of key land covers within its footprint, and how contributions varied at seasonal and interannual timescales. In addition, WRF-SPA simulated atmospheric CO₂ concentrations were compared with two coarse global inversion models, CarbonTrackerEurope and the National Oceanic and Atmospheric Administration's CarbonTracker (CTE-CT). WRF-SPA realistically modelled both seasonal (except post harvest) and daily cycles seen in observed atmospheric CO₂ at the tall tower (<i>R</i>² = 0.67, rmse = 3.5 ppm, bias = 0.58 ppm). Atmospheric CO₂ concentrations from the tall tower were well simulated by CTE-CT, but the inverse model showed a poorer representation of diurnal variation and simulated a larger bias from observations (up to 1.9 ppm) at seasonal timescales, compared to the forward modelling of WRF-SPA. However, we have highlighted a consistent post-harvest increase in the seasonal bias between WRF-SPA and observations. Ecosystem-specific tracers of CO₂ exchange indicate that the increased bias is potentially due to the representation of agricultural processes within SPA and/or biases in land cover maps. The ecosystem-specific tracers also indicate that the majority of seasonal variation in CO₂ uptake for Scotland's dominant ecosystems (forests, cropland and managed grassland) is detectable in observations within the footprint of the tall tower; however, the amount of variation explained varies between years. The between years variation in detectability of Scotland's ecosystems is potentially due to seasonal and interannual variation in the simulated prevailing wind direction. This result highlights the importance of accurately representing atmospheric transport used within atmospheric inversion models used to estimate terrestrial source/sink distribution and magnitude

The assessment of sustained attention in Multiple Sclerosis: comparison of psychometric measures and correlates with everyday cognitive function

Multiple Sclerosis (MS) is the most common disabling neurological disease affecting young and middle-aged adults (Arnett, 2003). It is only in recent years however that the influence of cognitive impairment as a causal factor in disability in MS has been recognised. Despite clinical recognition and anecdotal reports of attentional difficulties the status of attention in MS arguably remains unclear with inconsistent findings in the research literature. The impact of sustained attention was discerned from other theoretical types of attention and the assessment of it provided the focus for study.The Sustained Attention to Response Task (SART) was developed for using with the traumatic brain-injured population and is purported to be a sensitive and valid measure of sustained attention. The main aim of the study was to investigate whether performance on it could be replicated with an MS population. The principal hypothesis stated that there would be a significant difference between a sample of MS patients and a healthy control group across attentional measures. The Lottery and Elevator Counting subtests from the Test of Everyday Attention, the Symbol Digits Modalities Test formed the main assessment tools used. Another aim of the study was to determine how well performance on these tests predicted everyday cognitive functioning, as measured by the self and informant-reported Cognitive Failures Questionnaire.The results demonstrated that sustained attention deficits were indeed a part of the cognitive profile in this sample of MS patients. In its current format performance on the SART was not found to be a valid measure for using with the MS population. The other three attentional tests were however able to discern a significant difference in performance between the two groups. Performance on these test were also found to significantly correlated with and hence be predictive of everyday cognitive functioning as measured by the informant-reported Cognitive Failures Questionnaire

Journey to Internal Medicine

My name is Dr. Williams, or as most people call me Dr. Luke. Currently, I work in South Georgia as an ED physician. The road to where I’m currently sitting and to where I started has been long, trying but mostly fun! I started my undergraduate at Valdosta State University; to say the least I was completely lost. My hometown has about 5000 people in the entire county so being at a bigger city seemed overwhelming. I had no friends really and my social life was subpar. I started out as a premed major but quickly realized that these college professors were in the businesses of “weeding” out students. My first bio class I made a C! Devastated but not out, I realized that if my dreams were to become reality it was going to take more dedication, time, and discipline. The first tool I can give you in regards to discipline is found in the book The Road Less Traveled. There is a chapter in the book that talks about “Delaying Gratification” or as in movie I watched a few years ago when the father told his son, “we do what we have to so we can do what we want to”. Just think about this for a while. Are you willing to say no to going out in order to study, miss family functions and events, and basically willing to accumulate more debt that most people make in their lifetime of working? I was. After undergraduate, I applied to many “state” medical schools. My GPA was really good but MCAT was not so good. I did all of the Kaplan courses but just could not get my MCAT score up. I got wait listed but decided I did not want to take off an entire year. I applied to St. Matthews School of Medicine. This school is located in Grand Cayman! (small island located southwest of Cuba). My medical school changed my life. I had the opportunity to meet all types of people. We all came here with one goal and that was to become a medical doctor. While studying was strenuous and classes were grueling, I had the best time of my life. After graduating medical school, I applied to internal medicine residency. Being from Georgia, I wanted to stay close to home. I was accepted into Mercer IM, located in Macon, GA. I spent the next 3 years of my life in the hospital. Hours were strenuous in the hospital but as I grew in my residency, I realized there is no short cut to medicine. There is always something to learn; whether this pertains directly to the patient and their diagnosis and treatment plans to breaking difficult news to family members. Each step along the way was a building block to where I am now. My goal for us, is for you to ask as many questions as possible and we can learn from each other. I look forward to speaking to you soon