Using Personal Environmental Comfort Systems to Mitigate the Impact of Occupancy Prediction Errors on HVAC Performance

Heating, Ventilation and Air Conditioning (HVAC) consumes a significant fraction of energy in commercial buildings. Hence, the use of optimization techniques to reduce HVAC energy consumption has been widely studied. Model predictive control (MPC) is one state of the art optimization technique for HVAC control which converts the control problem to a sequence of optimization problems, each over a finite time horizon. In a typical MPC, future system state is estimated from a model using predictions of model inputs, such as building occupancy and outside air temperature. Consequently, as prediction accuracy deteriorates, MPC performance--in terms of occupant comfort and building energy use--degrades. In this work, we use a custom-built building thermal simulator to systematically investigate the impact of occupancy prediction errors on occupant comfort and energy consumption. Our analysis shows that in our test building, as occupancy prediction error increases from 5\% to 20\% the performance of an MPC-based HVAC controller becomes worse than that of even a simple static schedule. However, when combined with a personal environmental control (PEC) system, HVAC controllers are considerably more robust to prediction errors. Thus, we quantify the effectiveness of PECs in mitigating the impact of forecast errors on MPC control for HVAC systems.Comment: 21 pages, 13 figure

Strengthening Social Networks of Youth Aging Out of Foster Care: Promoting Positive Adult Outcomes

During the transition to adulthood, youth often rely on the people in their life for support. However, for transition-aged foster youth, these supports may not be available or may look different than supports available to youth in the general population. Relationships with supportive adults have been found to help former foster youth transition to adulthood, but little is known about the adults youth have in their network. Foster youth who report increased levels of social capital have been shown to experience higher levels of success in young adulthood. However, as former foster youth transition to adulthood, a lack of in-depth understanding of supportive adults and social networks creates difficulties identifying—and addressing—potential gaps in their social network. This study aims to gain a better understanding of how social networks influence social support and access to and mobilization of social capital as youth leave the foster care system. A social network assessment based on two existing measures was created to attain a better understanding of the social networks of transition-aged foster youth. The new social network tool was piloted with a group of young adults prior to use in this study. This social network tool allowed for an in-depth understanding of social networks, social support, and social capital as three distinct constructs. The social network characteristics included: on whom the youth relies for support, how the relationship developed, and the closeness of the relationship. Social support included: questions on the type of support available to youth (resources, emotional, advice, or constructive criticism), as well as the social support domains (housing, education, employment, relationships, and transportation). Social capital was examined based on questions about network members’ occupation(s) and frequency of communication between the youth and each network member. Univariate, Bivariate, and Multivariate analyses were utilized to examine social network characteristics, foster care history, social support, and social capital. The mean network size of sample participants was 7.1 and the range was 0–36. A relationship between placement type and social network members was found; indicating that youth in congregate care were more likely to have formal (social service related) networks than youth not in congregate care. A relationship between having more informal network members and housing stability was found; indicating that different network members may help youth with different young adult outcomes. A relationship between both access to, and mobilization of, social capital was found based on the type of social network members (formal, informal, familial-biological, familial-foster). Based on the findings of the current study, research and practice implications are discussed. These include the utility of social network analysis with transition-aged foster youth, future lines of inquiry, and suggested practice/policy shifts

Antibiotic-resistant bacteria in wastewater and potential human exposure through wastewater reuse

As community-acquired antibiotic-resistant bacterial infections occur with increasing frequency, it is important to identify possible environmental reservoirs for these organisms. My dissertation evaluated the presence of antibiotic-resistant bacteria in U.S. wastewater intended for reuse and the related public health implications. My objectives were to: 1) Evaluate wastewater from four U.S. wastewater treatment plants (WWTPs) for the presence of methicillin-resistant Staphylococcus aureus (MRSA); 2) Evaluate the occurrence of vancomycin-resistant enterococci (VRE) at four U.S. WWTPs from which treated wastewater is reused; and 3) Determine and compare MRSA, methicillin-susceptible S. aureus (MSSA), VRE, and vancomcyin-susceptible enterococci (VSE) colonization among American reclaimed water spray irrigators and controls. Between 2009 and 2010, 44 wastewater samples were collected from four WWTPs, two in the Mid-Atlantic and two in the Midwest regions of the U.S. I analyzed samples for MRSA and VRE using standard membrane filtration. For the third objective, I collected 94 nasal and dermal swabs from 19 spray irrigators and 24 controls and analyzed them for MRSA, MSSA, VRE, and VSE. I confirmed all isolates and performed antimicrobial susceptibility testing by microbroth dilution. Statistical analyses included two-sample proportion tests and logistic regression. MRSA and VRE were detected at all WWTPs. The percentage of MRSA-positive samples and concentration of VRE decreased as treatment progressed. Neither MRSA nor VRE were identified in tertiary-treated samples, but I identified both in an un-chlorinated effluent sample. No MRSA or VRE were detected in nasal or dermal samples from spray irrigators or controls. MSSA and VSE were detected in 26% and 11% of spray irrigators and 29% and 0% of controls, respectively. The odds of MSSA, MDR MSSA, and either MSSA or VSE colonization were not significantly different between the spray irrigators and controls. My dissertation includes the first reports of MRSA at U.S. WWTPs and VRE at WWTPs whose effluent is intended for reuse. This is also the first U.S. evaluation of occupational exposure to antibiotic-resistant bacteria in reclaimed water. My findings provide additional scientific evidence that antibiotic-resistant bacteria can survive secondary-treated wastewater and may cause increased risks for infection among individuals exposed to reclaimed water

EVALUATION OF ANTIBIOTIC-RESISTANT BACTERIA IN TERTIARY TREATED WASTEWATER, RECLAIMED WASTEWATER USED FOR SPRAY IRRIGATION, AND RESULTING OCCUPATIONAL EXPOSURES

Occupational exposures to vancomycin-resistant Enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) in reclaimed wastewater used for spray irrigation were evaluated. In 2009, wastewater was collected from a tertiary-treatment facility, and reclaimed wastewater, nasal and dermal swab samples from an irrigation site. Samples were evaluated for MRSA and VRE using standard methods, PCR, and susceptibility testing. MRSA and VRE were isolated from all wastewater samples except effluent. While wastewater MRSA isolates were multidrug resistant (98%), no MRSA was isolated in irrigation water or swabs. VRE was isolated in one irrigation water sample. Fewer irrigation workers were colonized with S. aureus (31%) compared to controls (46%), but they harbored more multidrug resistant S. aureus. This is the first study to 1) evaluate antibiotic-resistant bacteria (ARB) in U.S. reclaimed wastewater and resulting occupational exposures, and 2) detect MRSA in U.S. wastewater. The findings suggested that tertiary wastewater treatment effectively reduced MRSA and VRE

Evidence-based Target Recall Rates for Screening Mammography 1

PURPOSE: To retrospectively identify target recall rates for screening mammography on the basis of how sensitivity shifts with recall rate. MATERIALS AND METHODS: The study group included 1 872 687 subsequent and 171 104 first screening mammograms from 1996 to 2001 from 172 and 139 facilities, respectively, in six sites of the Breast Cancer Surveillance Consortium. Institutional review board (IRB) approval was obtained from each site. Informed consent requirements of the IRBs were followed. The study was HIPAA compliant. Recall rate was defined as the percentage of screening studies for which further work-up was recommended by the radiologist. Sensitivity was defined as the proportion of cancers that were detected at screening mammography. Piecewise linear regression was used to model sensitivity as a function of recall rate. This model allows detection of critical recall rates in which significant changes (shifts) occurred in the rates that sensitivity increased with increasing recall rate. Rates were interpreted as number of additional work-ups per additional cancer detected (AW/ACD) or, in other words, the estimated number of additional women needed to be recalled at a given rate to detect one additional cancer. RESULTS: For first mammograms, a single shift in the estimated AW/ACD rate occurred at a recall rate of 10.0%, with the rate jumping dramatically from 35 to 172. For subsequent mammograms, four shifts were identified. At a recall rate of 6.7%, the estimated AW/ACD increased from 80 to 132, which rendered it the highest desirable target recall rate. At a recall rate of 12.3%, the estimated AW/ACD was 304, which suggests little benefit for any higher recall rate. CONCLUSION: Recall rates of 10.0% for first and 6.7% for subsequent mammograms are recommended targets on the basis of their AW/ACD rates (less than 100)

Tracking microhabitat temperature variation with iButton data loggers

Applications in Plant Sciences is published by Wiley Periodicals, Inc. on behalf of the Botanical Society of America Premise of the Study: Fine-scale variation in temperature and soil moisture contribute to microhabitats across the landscape, affecting plant phenology, distribution, and fitness. The recent availability of compact and inexpensive temperature and humidity data loggers such as iButtons has facilitated research on microclimates. Methods and Results: Here, we highlight the use of iButtons in three distinct settings: comparisons of empirical data to modeled climate data for rare rock ferns in the genus Asplenium in eastern North America; generation of fine-scale data to predict flowering time and vernalization responsiveness of crop wild relatives of chickpea from southeastern Anatolia; and measurements of extreme thermal variation of solar array installations in Vermont. Discussion: We highlight a range of challenges with iButtons, including serious limitations of the Hygrochron function that affect their utility for measuring soil moisture, and methods for protecting them from the elements and from human interference. Finally, we provide MATLAB code to facilitate the processing of raw iButton data