The effect of water temperature and reactor geometry on turbulent flocculation

This research is intended to give the water treatment industry a better understanding of how the coagulation/flocculation process can be optimized for treatment of cold waters. The following work was performed during this study: (1) Two particle/floc measuring techniques were evaluated; The HIAC particle counter, and fully automated image analysis. (2) An investigation of the effect of reactor geometry, mixing intensity, and pH on flocculation efficiency in a batch reactor at high (20°C) and low (5°C) temperature;The testing performed on the floc measuring systems has established that the HIAC automatic particle counting system has some severe limitations, and under certain conditions the HIAC causes severe floc breakup;The flocculation tests were performed using two impeller geometries; the turbine and the stake and stator. The primary particles were kaolinite and they were flocculated using alum, ferric sulfate, or a cationic polymer (MagniFloc 573C). The flocculation was carried out in the adsorption/destabilization region. The following conclusions are drawn: (1) Temperature and geometry both have a significant impact on the kinetics of primary particle removal, the structure of the floc formed, and the strength of the floc formed. (2) The primary particle removal efficiency of the turbine geometry is less effected by temperature than the efficiency of the stake and stator geometry. This difference is related to the structure of the turbulent flow field produced by the two impellers. (3) When using metal salts as the primary coagulant it is appropriate to hold the system pOH constant, rather than the system pH, as the temperature changes. (4) The particle removal characteristics of the polymer and metal salts were radically different, with the salts performing better than the polymer in sweeping up the primary particles. The polymer produced larger, stronger floc, but left more primary particles

Ecosystem respiration: Drivers of daily variability and background respiration in lakes around the globe

We assembled data from a global network of automated lake observatories to test hypotheses regarding the drivers of ecosystem metabolism. We estimated daily rates of respiration and gross primary production (GPP) for up to a full year in each lake, via maximum likelihood fits of a free‐water metabolism model to continuous high‐frequency measurements of dissolved oxygen concentrations. Uncertainties were determined by a bootstrap analysis, allowing lake‐days with poorly constrained rate estimates to be down‐weighted in subsequent analyses. GPP and respiration varied considerably among lakes and at seasonal and daily timescales. Mean annual GPP and respiration ranged from 0.1 to 5.0 mg O2 L−1 d−1 and were positively related to total phosphorus but not dissolved organic carbon concentration. Within lakes, significant day‐to‐day differences in respiration were common despite large uncertainties in estimated rates on some lake‐days. Daily variation in GPP explained 5% to 85% of the daily variation in respiration after temperature correction. Respiration was tightly coupled to GPP at a daily scale in oligotrophic and dystrophic lakes, and more weakly coupled in mesotrophic and eutrophic lakes. Background respiration ranged from 0.017 to 2.1 mg O2 L−1 d−1 and was positively related to indicators of recalcitrant allochthonous and autochthonous organic matter loads, but was not clearly related to an indicator of the quality of allochthonous organic matter inputs

Development of Department Writing Guide for Civil Engineering

This paper describes the development of a writing guide for a civil engineering department. Motivation for developing a writing guide came from several sources. Freshmen enrolled in an introduction to civil engineering course turned in writing assignments demonstrating a need for improvement. The introductory course is frequently taken concurrently with a required freshman level writing class and well before a required discipline specific advanced writing class, so this was generally expected. Continued issues in junior and senior level classes, however, have clarified the need for additional program focus on written communication. Students have continually expressed frustration at having to adapt to varying lab report expectations from different faculty members and, most importantly, capstone design reports have demonstrated that student writing is not at industry expectations. The writing guide was a collaborative effort between civil engineering faculty and writing studies faculty. The initial phase focused on defining the content of the writing guide: reports (lab, project, etc.), memos, homework submittals, figures, tables, equations, professional e-mails, and references. The second phase was to develop an outline for the rubrics; the goal was for the rubrics to be general enough to be adapted by each faculty member for a given assignment, but still provide students with a consistent outline to assess their writing prior to submitting it for grade. Finally, in the third phase, the level of detail in the writing guide was discussed. In order to be useful, the writing guide was made specific enough for the students to use it to successfully complete writing assignments but general enough to allow individual faculty to adapt assignments toward the specific outcomes in each course. Above all else, the main goal of the writing guide is to prepare students for real world written communication. Therefore, it must not leave students with the impression that there is a template that can be applied regardless of audience. These concerns were considered during the development of the writing guide and will be part of in-class writing instruction within both civil engineering and writing courses. Written work will be assessed using both university and ABET assessment processes. Example work collected as part of the ABET process from the Fall 2012 semester will be retroactively assessed using the newly developed rubrics. In addition, Fall 2014 work will be assessed as it is submitted. Spring 2015 work will represent the first semester using the department writing guide. Pre-writing guide assessments will be compared to assessments of writing after the department guide is introduced. By comparing work over the next several years, senior year writing submittals will be used to determine if a greater level of competency was achieved by students exposed to the writing guide for their entire undergraduate experience as compared to students who received the writing guide late in their undergraduate career

Value at Risk models with long memory features and their economic performance

We study alternative dynamics for Value at Risk (VaR) that incorporate a slow moving component and information on recent aggregate returns in established quantile (auto) regression models. These models are compared on their economic performance, and also on metrics of first-order importance such as violation ratios. By better economic performance, we mean that changes in the VaR forecasts should have a lower variance to reduce transaction costs and should lead to lower exceedance sizes without raising the average level of the VaR. We find that, in combination with a targeted estimation strategy, our proposed models lead to improved performance in both statistical and economic terms

Binational reflections on pathways to groundwater security in the Mexico-United States borderlands

Shared groundwater resources between Mexico and the United States are facing unprecedented stressors. We reflect on how to improve water security for groundwater systems in the border region. Our reflection begins with the state of groundwater knowledge, and the challenges groundwater resources face from a physical, societal and institutional perspective. We conclude that the extent of ongoing cooperation frameworks, joint and remaining research efforts, from which alternative strategies can emerge, still need to be developed. The way forward offers a variety of cooperation models as the future offers rather complex, shared and multidisciplinary water challenges to the Mexico–US borderlands

Binational reflections on pathways to groundwater security in the Mexico–United States borderlands

Shared groundwater resources between Mexico and the United States are facing unprecedented stressors. We reflect on how to improve water security for groundwater systems in the border region. Our reflection begins with the state of groundwater knowledge, and the challenges groundwater resources face from a physical, societal and institutional perspective. We conclude that the extent of ongoing cooperation frameworks, joint and remaining research efforts, from which alternative strategies can emerge, still need to be developed. The way forward offers a variety of cooperation models as the future offers rather complex, shared and multidisciplinary water challenges to the Mexico–US borderlands

Gender Differences in Russian Colour Naming

In the present study we explored Russian colour naming in a web-based psycholinguistic experiment (http://www.colournaming.com). Colour singletons representing the Munsell Color Solid (N=600 in total) were presented on a computer monitor and named using an unconstrained colour-naming method. Respondents were Russian speakers (N=713). For gender-split equal-size samples (NF=333, NM=333) we estimated and compared (i) location of centroids of 12 Russian basic colour terms (BCTs); (ii) the number of words in colour descriptors; (iii) occurrences of BCTs most frequent non-BCTs. We found a close correspondence between females’ and males’ BCT centroids. Among individual BCTs, the highest inter-gender agreement was for seryj ‘grey’ and goluboj ‘light blue’, while the lowest was for sinij ‘dark blue’ and krasnyj ‘red’. Females revealed a significantly richer repertory of distinct colour descriptors, with great variety of monolexemic non-BCTs and “fancy” colour names; in comparison, males offered relatively more BCTs or their compounds. Along with these measures, we gauged denotata of most frequent CTs, reflected by linguistic segmentation of colour space, by employing a synthetic observer trained by gender-specific responses. This psycholinguistic representation revealed females’ more refined linguistic segmentation, compared to males, with higher linguistic density predominantly along the redgreen axis of colour space

Long-term therapy of interferon-alpha induced pulmonary arterial hypertension with different PDE-5 inhibitors: a case report

BACKGROUND: Interferon alpha2 is widely used in hepatitis and high-risk melanoma. Interferon-induced pulmonary arterial hypertension as a side effect is rare. CASE PRESENTATION: We describe a melanoma patient who developed severe pulmonary arterial hypertension 30 months after initiation of adjuvant interferon alpha2b therapy. Discontinuation of interferon did not improve pulmonary arterial hypertension. This patient could be treated successfully with phosphodiesterase-5 inhibitor therapy. CONCLUSION: This is only the 5th case of interferon-induced pulmonary arterial hypertension and the first documented case where pulmonary arterial hypertension was not reversible after termination of interferon alpha2 therapy. If interferon alpha2 treated patients develop respiratory symptoms, pulmonary arterial hypertension should be considered in the differential diagnosis. For these patients phosphodiesterase-5 inhibitors, e.g. sildenafil or vardenafil, could be an effective therapeutic approach