Does clinician-initiated Clostridioides difficile testing improve outcomes of patients with Clostridioides Difficile infection?

BACKGROUND: Clostridioides difficile (C. difficile) is a common hospital-acquired infection which can lead to major implications for patients and our health care system. In this study, we examine a policy change at a single-site Veterans Affairs Healthcare system that allowed bedside nurses to order C. difficile testing in addition to physicians on the time to obtain test results and initiate treatment. METHODS: The time to receive results and initiate treatment were analyzed before and after the policy change, and between physicians and nurses using descriptive statistics and paired student t-tests. Variables associated with lower ordering times were also analyzed using logistic regression while adjusting for patient admission location and length of inpatient hospital stay. RESULTS: The difference in time to obtain the result both before and after the policy change and between ordering provider type were both statistically significant (P < .05). In unadjusted models, nurses were associated with faster test results compared to physicians (OR (95% CI) 1.72 (1.45-2.05). CONCLUSIONS: Allowing bedside nurses more autonomy to order the stool sample significantly decreased the amount of time to receive the results, potentially decreasing the risk of additional infections among patients and decreasing the economic burden on the hospital.

The Prevalence and Trends of Instrumental Activities of Daily Living Impairments in the United States from 2008-2018.

Background: Instrumental activities of daily living (IADL) are neuropsychological-driven tasks that are linked to cognitive dysfunction. Examining population-based IADL deficits may reveal insights for the presence of these impairments in the United States. Objective: This investigation sought to evaluate the prevalence and trends of IADL impairments in Americans. Methods: A secondary analysis of data from the 2006-2018 waves of the Health and Retirement Study was conducted. The overall unweighted analytic sample included 29,764 Americans aged≥50 years. Respondents indicated their ability to perform six IADLs: manage money, manage medications, use a telephone, prepare hot meals, shop for groceries, and use a map. Persons reporting difficulty or an inability to complete an individual IADL were considered as having a task-specific impairment. Similarly, those indicating difficulty or an inability to perform any IADL were classified as having an IADL impairment. Sample weights were utilized to generate nationally-representative estimates. Results: Having an impairment in using a map (2018 wave: 15.7% (95% confidence interval (CI): 15.0-16.4) had the highest prevalence in individual IADLs regardless of wave examined. The overall prevalence of IADL impairments declined during the study period (p < 0.001) to 25.4% (CI: 24.5-26.2) in the 2018 wave. Older Americans and women had a consistently higher prevalence of IADL impairments compared to middle-aged Americans and men, respectively. The prevalence of IADL impairments was also highest among Hispanics and non-Hispanic Blacks. Conclusion: IADL impairments have declined over time. Continued surveillance of IADLs may help inform cognitive screening, identify subpopulations at risk of impairment, and guide relevant policy.

Taenia crassiceps Cysticercosis in a Wild Muskrat and a Domestic Dog in the Northeastern United States.

Taenia crassiceps is a parasite of wild canids and dogs that serve as definite hosts, harboring the adult cestode, whereas rodents are the intermediate hosts in which the metacestode/cysticercus/larval stage occurs. Fecal-oral transmission ensures the parasite's lifecycle. At times, dogs and humans act as accidental intermediate hosts. Despite the public health concern this parasite warrants, its epidemiology remains unclear. In this report, we document the occurrence of metacestodes of T. crassiceps in a muskrat (Ondatra zibethicus) and a domestic dog from the northeastern United States, a development that necessitates increased awareness and surveillance to tackle this disease of "one health" significance. Taenia crassiceps cysticercosis was confirmed in an adult male muskrat in February 2018 and in a 4-year-old female spayed Staffordshire Bull Terrier in December 2020. Parasitological and histopathologic examination of both cases revealed cysticerci with the characteristic rostellar hook morphology that aided in Taenia species identification. In the muskrat case specifically, partial sequencing of the mitochondrial cytochrome oxidase gene confirmed the species identity as T. crassiceps. We report T. crassiceps occurrence in a muskrat in New York State for the first time and document a case presentation in a domestic dog from New Jersey that was infected with metacestode stages of this parasite. Given the detection of this parasite in the northeastern United States, T. crassiceps infection, which otherwise is considered a rare disease, should be on the radar of veterinary, medical and wildlife biologists for timely diagnosis and interventions.

Evaluation of adenosine triphosphate bioluminescence-based system in rooms occupied by patients with methicillin resistant Staphylococcus aureus.

Background: Adenosine triphosphate (ATP)-based monitoring systems can detect the amount of organic matter that remains on hospital surfaces after cleaning. We evaluated an ATP-based monitoring system in assessing contamination of high touched objects in rooms occupied by patients on methicillin resistant S. aureus precautions. Methods: We compared the ATP to standard aerobic cultures as well as to gloved hand culture to predict risk of healthcare-worker hand contamination. Results: More than a third of high touch object surfaces were measured unclean with ATP yet only reflects about 5% chance of contaminating healthcare-workers' hands. Conclusions: Our study emphasizes the shortcomings of using the ATP system even in pathogen specific environment such as surfaces in methicillin resistant S. aureus rooms.

Handgrip Strength Asymmetry and Weakness Are Associated With Future Morbidity Accumulation in Americans.

ABSTRACT: Klawitter, L, Vincent, BM, Choi, BJ, Smith, J, Hammer, KD, Jurivich, DA, Dahl, LJ, and McGrath, R. Handgrip strength asymmetry and weakness are associated with future morbidity accumulation in americans. J Strength Cond Res 36(1): 106-112, 2022-Identifying strength asymmetries in physically deconditioned populations may help in screening and treating persons at risk for morbidities linked to muscle dysfunction. Our investigation sought to examine the associations between handgrip strength (HGS) asymmetry and weakness on accumulating morbidities in aging Americans. The analytic sample included 18,506 Americans aged ≥50 years from the 2006-2016 Health and Retirement Study. Handgrip strength was measured on each hand with a handgrip dynamometer, and persons with an imbalance in strength >10% between hands had HGS asymmetry. Men with HGS <26 kg and women with HGS <16 kg were considered as weak. Subjects reported the presence of healthcare provider-diagnosed morbidities: hypertension, diabetes, cancer, chronic lung disease, cardiovascular disease, stroke, arthritis, and psychiatric problems. Covariate-adjusted ordinal generalized estimating equations analyzed the associations for each HGS asymmetry and weakness group on future accumulating morbidities. Of those included in our study, subjects at baseline were aged 65.0 ± 10.2 years, 9,570 (51.7%) had asymmetric HGS, and 996 (5.4%) were weak. Asymmetry alone and weakness alone were associated with 1.09 (95% confidence interval [CI]: 1.04-1.14) and 1.27 (CI: 1.11-1.45) greater odds for future accumulating morbidities, respectively. Having both HGS asymmetry and weakness was associated with 1.46 (CI: 1.29-1.65) greater odds for future accumulating morbidities. Handgrip-strength asymmetry, as another potential indicator of impaired muscle function, is associated with future morbidity status during aging. Exercise professionals and related practitioners should consider examining asymmetry and weakness with handgrip dynamometers as a simple and noninvasive screening method for helping to determine muscle dysfunction and future chronic disease risk.

Comparison of Renal Function Between Tenofovir Disoproxil Fumarate and Other Nucleos(t)ide Reverse Transcriptase Inhibitors in Patients With Hepatitis B Virus Infection.

BACKGROUND: Nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs) have become a standard treatment for both HIV and hepatitis B virus (HBV) infections. Tenofovir disoproxil fumarate (TDF) has been associated with kidney injury and possible long-term damage in patients with HIV. Few studies have examined whether this holds true for patients treated for HBV. METHODS: Data were gathered from the Veterans Health Administration Corporate Data Warehouse between July 1, 2005 and July 31, 2015. Patients aged ≥ 18 years with HBV infection and prescribed a NRTI for > 1 month were included in the study and followed for 36 months. Patients with HIV infection were excluded, and patients treated with combination TDF/emtricitabine were analyzed separately from patients receiving only TDF. A linear mixed model was used to examine the effects of time and specific agent on renal function, which was measured with estimated glomerular filtration rate (eGFR) at various time intervals. RESULTS: There were 413 incidences of NRTI use in 308 subjects during the 10 years of the study with 39 cases of TDF use. There was a significant fixed effect of time, with eGFR reduction of 4.6 mL/min (P < .001) over the course of the study for the full cohort, but the effects of each medication were not significant. CONCLUSIONS: This multicenter, retrospective study did not demonstrate an association between TDF use and a greater degree of kidney injury compared with other NRTIs in patients with HBV, but further studies are warranted.

Effect of pulsed-xenon ultraviolet light on environmental contamination and risk of health care worker hand contamination.

In this study, we conducted a prospective survey of a convenience sample of high touch objects using adenosine triphosphate bioluminescence surface sample readings, aerobic cultures, and gloved hand methicillin-resistant Staphylococcus aureus imprint cultures to assess inpatient room cleanliness. We demonstrated that thoroughness of cleaning is improved with housekeeping education and feedback and that the addition of automated decontamination with pulsed UV irradiation provides further benefit in decontamination and subsequent risk for health care worker hand contamination.

Methicillin-resistant Staphylococcus aureus (MRSA) screening upon inpatient hospital admission: Is there concordance between nasal swab results and samples taken from skin and soft tissue?

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infections are associated with increased mortality and healthcare costs. In 2007, a Veterans' Affairs (VA) hospital implemented a MRSA nasal screening program, following a nationwide VA mandate, in an effort to reduce healthcare-associated MRSA infections. OBJECTIVE: To evaluate the correlation between the nasal screening results for MRSA and culture results of wound and tissue sites. METHODS: This retrospective study was conducted on inpatients at our VA hospital. Patients were included if they had undergone nasal screening for MRSA plus culture of a wound or tissue site within 30 days of hospital admission. RESULTS: In total, 337 patients underwent nasal screening and wound culture and 211 underwent nasal screening and wound and tissue cultures. The prevalence of MRSA nasal colonization was 14.2% for wound samples and 15.2% for tissue samples. The sensitivities of MRSA nasal screening for detecting MRSA were 64.6% for wound cultures and 65.5% for tissue cultures. Specificities were 86.2% and 88.8% for wound and tissue cultures, respectively. The positive predictive values (PPVs) were 43.7% and 51.2% for wound and tissue cultures, respectively, and the negative predictive values (NPVs) were high at 93.6% and 93.5%, respectively. CONCLUSIONS: In cases of wound or tissue samples for which culture results are pending, a negative MRSA nasal swab may be a component of the decision to withhold or discontinue MRSA-active agents.

Longitudinal study on the detection of Clostridioides difficile at the Fargo Veteran Affairs Community Living Center.

Our study used C Diff Banana Broth to evaluate the occurrence of positive Clostridioides difficile spores in new and preexisting hospital rooms. C difficile incidence was 5.5%. Analysis using multiple linear regression found that rooms with contact precautions in place were significant predictors of a positive sample (P ≤ .001). Room occupancy was not a significant predictor (P = .544). Thus it could be interpreted that the environment can be a significant carrier for C difficile.

Factors Impacting Perceived Access to Early Prenatal Care among Pregnant Veterans Enrolled in the Department of Veterans Affairs.

BACKGROUND: Despite the relatively recent Department of Veterans Affairs (VA) policy advances in providing care for veterans and their infants during the perinatal period, little information exists regarding access to prenatal care for women veterans. Currently, VA medical centers do not provide onsite pregnancy care for veterans, but pay for care from community obstetricians through the Veterans Choice Program (VCP) and related non-VA care programs. The VCP is subcontracted to two large contractors, Health Net and TriWest, to assist the VA in administering the VCP. To date, no studies have evaluated women's perceived access to prenatal care under the VCP. OBJECTIVE: The purpose of this study was to understand pregnant veterans' perceived access to community prenatal care through the VCP. DESIGN: The Center for Maternal and Infant Outcomes Research in Translation (COMFORT) study is a longitudinal, prospective multisite observational cohort study of pregnant and postpartum veterans at 15 VA facilities nationwide. Telephone surveys were conducted with women veterans at 20 weeks of pregnancy. We used multivariable logistic regression to examine the odds of receiving care early enough adjusted for these key factors. Measures included perceived access to early prenatal care by race, age, marital status, history of mental health conditions, urban/rural residence, and the VCP contractor (Health Net vs. TriWest). RESULTS: Overall, 519 women veterans completed the baseline pregnancy survey. A sizeable proportion of participants reported a history of mental health conditions, including depression (56.7%), anxiety disorder (45.5%), and posttraumatic stress disorder (40.5%). White veterans were more likely to report perceived timely access to prenatal care than minority veterans (66% vs. 52%; p = .0038). Veterans receiving care at Health Net facilities were more likely to report receiving prenatal care as early as desired in comparison to veterans at TriWest facilities (adjusted odds ratio, 0.48; 95% CI, 0.32-0.73), whereas veterans with a history of depression were 1.7 times more likely to report perceived delays in desired prenatal care compared with veterans without a history of depression (adjusted odds ratio, 1.65; 95% CI, 1.08-2.53). CONCLUSIONS: We found that nearly one-third of women reported problems receiving early prenatal care as soon as they would have liked. Women with histories of depression and racial minorities may require additional maternity care coordination services to ensure they receive timely prenatal care. Community-based provider networks under the VCP should continue to be expanded so that pregnant veterans are able to access high-quality prenatal care in a timely manner.

A systematic review and meta-analysis on the use of prophylactic topical antibiotics for the prevention of uncomplicated wound infections.

BACKGROUND: The prescription of topical antibiotics for the prevention of infections in uncomplicated wounds is common. However, the efficacy is not well reported. Therefore, the objective of the study was to conduct a systematic review and meta-analysis of the available evidence on prevention of uncomplicated wound infections by prophylactic topical antibiotics. MATERIALS AND METHODS: The search included Pubmed, Google Scholar, SCOPUS, Embase, Cochrane, ClinicalTrials.gov, International Clinical Trials Registry Platform, National Technical Information Service, and the National Guidelines Clearinghouse. RESULTS: We identified eight randomized controlled trials and four quasi-randomized trials that met the criteria for the systematic review. Of these trials, 11 studies were pooled for meta-analysis to compare the effects of topical antibiotics versus placebo and 4 studies were pooled for comparison of effects of topical antibiotics versus topical antiseptics on uncomplicated wounds. Fewer wound infections occurred in the topical antibiotic arms compared to placebo (pooled risk ratio: 0.57 [95% CI: 0.37 to 0.86]; p=0.01 and pooled risk difference: -3.1% [95% CI: -5.8% to -0.34%]; p=0.03). Compared to antiseptics, topical antibiotics demonstrated statistically significant relative risk reduction (pooled risk ratio: 0.56 [95% CI: 0.23 to 0.91]; p=0.02), while there was no significant absolute risk reduction (pooled risk difference: -3.7% [95% CI: -7.9% to +0.6%]; p=0.09). CONCLUSION: Topical antibiotics are effective in reducing wound infections after surgical procedures, but the absolute benefit is small. Given the global emergence of antimicrobial resistance, judicious use of antibiotics is encouraged and use of antiseptics should be considered as a reasonable alternative to topical antibiotics.

Risky Driving Behaviors for Older Adults: Differences by Veteran's Status.

Veterans are at an increased risk of being injured or killed in motor vehicle crashes, potentially due to their proclivity to engage in risky driving behaviors. However, most research in this area has focused on driving behaviors of veterans who have recently returned home after deployment. No research has focused on risky driving behaviors of older veterans (aged 65 or older) and if risky driving behaviors extend beyond the time period immediately following return from deployment. The purpose of this research is to determine if differences exist in risky driving behaviors of veterans and non-veterans aged 65 or older. This study used data from the 2011 National Health and Aging Trend Study (NHATS), a nationally representative, longitudinal survey of community-dwelling, Medicare beneficiaries aged 65 or older. Binary logistic regression analyses were conducted in 2017 to determine if veteran's status was predictive of specific risky driving behaviors. Veteran's status was found to be predictive of specific driving behaviors for adults aged 65 and older, with non-veterans significantly more likely than veterans to: not currently drive; avoid driving at night; avoid driving alone; avoid driving on busy roads or highways; and avoid driving in bad weather. The results of this study highlight the need to further understand the effects of veteran's status on risky driving behaviors among older adults, specifically, whether veteran's status compounds driving-related risks associated with aging-related physical and mental changes.

27-hydroxycholesterol: A novel player in molecular carcinogenesis of breast and prostate cancer.

Several studies have suggested an etiological role for hypercholesterolemia in the pathogenesis of breast cancer and prostate cancer (PCa). However, the molecular mechanisms that underlie and mediate the hypercholesterolemia-fostered increased risk for breast cancer and PCa are yet to be determined. The discovery that the most abundant cholesterol oxidized metabolite in the plasma, 27 hydroxycholesterol (27-OHC), is a selective estrogen receptor modulator (SERM) and an agonist of Liver X receptors (LXR) partially fills the void in our understanding and knowledge of the mechanisms that may link hypercholesterolemia to development and progression of breast cancer and PCa. The wide spectrum and repertoire of SERM and LXR-dependent effects of 27-OHC in the context of all facets and aspects of breast cancer and prostate cancer biology are reviewed in this manuscript in a very comprehensive manner. This review highlights recent findings pertaining to the role of 27-OHC in breast cancer and PCa and delineates the signaling mechanisms involved in the governing of different facets of tumor biology, that include tumor cell proliferation, epithelial-mesenchymal transition (EMT), as well as tumor cell invasion, migration, and metastasis. We also discuss the limitations of contemporary studies and lack of our comprehension of the entire gamut of effects exerted by 27-OHC that may be relevant to the pathogenesis of breast cancer and PCa. We unveil and propose potential future directions of research that may further our understanding of the role of 27-OHC in breast cancer and PCa and help design therapeutic interventions against endocrine therapy-resistant breast cancer and PCa.

The cholesterol metabolite 27-hydroxycholesterol stimulates cell proliferation via ERß in prostate cancer cells.

BACKGROUND: For every six men, one will be diagnosed with prostate cancer (PCa) in their lifetime. Estrogen receptors (ERs) are known to play a role in prostate carcinogenesis. However, it is unclear whether the estrogenic effects are mediated by estrogen receptor α (ERα) or estrogen receptor ß (ERß). Although it is speculated that ERα is associated with harmful effects on PCa, the role of ERß in PCa is still ill-defined. The cholesterol oxidized metabolite 27-hydroxycholesterol (27-OHC) has been found to bind to ERs and act as a selective ER modulator (SERM). Increased 27-OHC levels are found in individuals with hypercholesterolemia, a condition that is suggested to be a risk factor for PCa. METHODS: In the present study, we determined the extent to which 27-OHC causes deleterious effects in the non-tumorigenic RWPE-1, the low tumorigenic LNCaP, and the highly tumorigenic PC3 prostate cancer cells. We conducted cell metabolic activity and proliferation assays using MTS and CyQUANT dyes, protein expression analyses via immunoblots and gene expression analyses via RT-PCR. Additionally, immunocytochemistry and invasion assays were performed to analyze intracellular protein distribution and quantify transepithelial cell motility. RESULTS: We found that incubation of LNCaP and PC3 cells with 27-OHC significantly increased cell proliferation. We also demonstrate that the ER inhibitor ICI 182,780 (fulvestrant) significantly reduced 27-OH-induced cell proliferation, indicating the involvement of ERs in proliferation. Interestingly, ERß levels, and to a lesser extent ERα, were significantly increased following incubation of PCa cells with 27-OHC. Furthermore, in the presence of the ERß specific inhibitor, PHTPP, 27-OHC-induced proliferation is attenuated. CONCLUSIONS: Altogether, our results show for the first time that 27-OHC, through ER activation, triggers deleterious effect in prostate cancer cell lines. We propose that dysregulated levels of 27-OHC may trigger or exacerbate prostate cancer via acting on ERß.

Impact of eliminating reflex urine cultures on performed urine cultures and antibiotic use.

Inappropriate treatment of asymptomatic bacteriuria is often the result of unnecessary urinalyses and urine cultures. This study aimed to determine the impact of stopping the practice of reflex urine cultures. Our study demonstrated that stopping urine reflex cultures decreased the number of urine cultures performed and there was a trend toward a decrease in antibiotic use.

27-Hydroxycholesterol stimulates cell proliferation and resistance to docetaxel-induced apoptosis in prostate epithelial cells.

Although the causes of prostate cancer (PCa) and benign prostatic hyperplasia (BPH) are not known, the role of oxidative stress, aging, and diet are suspected to increase the incidence of prostate complications. The cholesterol oxidation derivative (oxysterol) 27-hydroxycholesterol (27-OHC) is the most prevalent cholesterol metabolite in the blood. As aging, oxidative stress, and hypercholesterolemia are associated with increased risk of PCa and BPH, and because 27-OHC levels are also increased with aging, hypercholesterolemia, and oxidative stress, determining the role of 27-OHC in the progression of PCas and BPH is warranted. In this study, we determined the effect of 27-OHC in human prostate epithelial cells RWPE-1. We found that 27-OHC stimulates proliferation and increases androgen receptor (AR) transcriptional activity. 27-OHC also increased prostate-specific antigen expression and enhanced AR binding to the androgen response element compared to controls. Silencing AR expression with siRNA markedly reduced the 27-OHC-induced proliferation. Furthermore, 27-OHC blocked docetaxel-induced apoptosis. Altogether, our results suggest that 27-OHC may play an important role in PCa and BPH progression by promoting proliferation and suppressing apoptosis.

The cholesterol metabolite 27-hydroxycholesterol regulates p53 activity and increases cell proliferation via MDM2 in breast cancer cells.

Estrogen is synthesized from cholesterol and high cholesterol levels are suggested to be associated with increased risk of estrogen receptor(ER)-positive breast cancer. The cholesterol metabolite 27-hydroxycholesterol (27-OHC) was recently identified as a selective estrogen receptor modulator (SERM) and may therefore impact breast cancer progression. However, the mechanisms by which 27-OHC may contribute to breast cancer are not all known. We determined the extent to which 27-OHC regulates cell proliferation in MCF7 ER-positive breast cancer cell line involving the tumor suppressor protein p53. We found that treatment of MCF7 cells with 27-OHC resulted reduced p53 transcriptional activity. Conversely, treatment of the ER-negative MDA-MB 231 cells with 27-OHC induced no significant change in p53 activity. Exposure of MCF7 cells to 27-OHC was also associated with increased protein levels of the E3 ubiquitin protein ligase MDM2 and decreased levels of p53. Moreover, 27-OHC also enhanced physical interaction between p53 and MDM2. Furthermore, 27-OHC-induced proliferation was attenuated using either the p53 activator Tenovin-1 or the MDM2 inhibitor Nutlin-3 and Mdm2 siRNA. Taken together, our results indicate that 27-OHC may contribute to ER-positive breast cancer progression by disrupting constitutive p53 signaling in an MDM2-dependent manner.

Phosphodiesterase 4D inhibitors limit prostate cancer growth potential.

UNLABELLED: Phosphodiesterase 4D (PDE4D) has recently been implicated as a proliferation-promoting factor in prostate cancer and is overexpressed in human prostate carcinoma. However, the effects of PDE4D inhibition using pharmacologic inhibitors have not been examined in prostate cancer. These studies examined the effects of selective PDE4D inhibitors, NVP-ABE171 and cilomilast, as anti-prostate cancer therapies in both in vitro and in vivo models. The effects of PDE4D inhibitors on pathways that are critical in prostate cancer and/or downstream of cyclic AMP (cAMP) were examined. Both NVP-ABE171 and cilomilast decreased cell growth. In vitro, PDE4D inhibitors lead to decreased signaling of the sonic hedgehog (SHH), androgen receptor (AR), and MAPK pathways, but growth inhibition was best correlated to the SHH pathway. PDE4D inhibition also reduced proliferation of epithelial cells induced by paracrine signaling from cocultured stromal cells that had activated hedgehog signaling. In addition, PDE4D inhibitors decreased the weight of the prostate in wild-type mice. Prostate cancer xenografts grown in nude mice that were treated with cilomilast or NVP-ABE171 had decreased wet weight and increased apoptosis compared with vehicle-treated controls. These studies suggest the pharmacologic inhibition of PDE4D using small-molecule inhibitors is an effective option for prostate cancer therapy. IMPLICATIONS: PDE4D inhibitors decrease the growth of prostate cancer cells in vivo and in vitro, and PDE4D inhibition has therapeutic potential in prostate cancer.

Dish-based high concentration PV system with Köhler optics.

We present work at the Steward Observatory Solar Lab on a high concentration photovoltaic system in which sunlight focused by a single large paraboloidal mirror powers many small triple-junction cells. The optical system is of the XRX-Köhler type, comprising the primary reflector (X) and a ball lens (R) at the focus that reimages the primary reflector onto an array of small reflectors (X) that apportion the light to the cells. We present a design methodology that provides generous tolerance to mis-pointing, uniform illumination across individual cells, minimal optical loss and even distribution between cells, for efficient series connection. An operational prototype has been constructed with a 3.3m x 3.3m square primary reflector of 2m focal length powering 36 actively cooled triple-junction cells at 1200x concentration (geometric). The measured end-to-end system conversion efficiency is 28%, including the parasitic loss of the active cooling system. Efficiency ~32% is projected for the next system.

Dish-based high concentration PV system with Köhler optics.

We present work at the Steward Observatory Solar Lab on a high concentration photovoltaic system in which sunlight focused by a single large paraboloidal mirror powers many small triple-junction cells. The optical system is of the XRX-Köhler type, comprising the primary reflector (X) and a ball lens (R) at the focus that reimages the primary reflector onto an array of small reflectors (X) that apportion the light to the cells. We present a design methodology that provides generous tolerance to mis-pointing, uniform illumination across individual cells, minimal optical loss and even distribution between cells, for efficient series connection. An operational prototype has been constructed with a 3.3m x 3.3m square primary reflector of 2m focal length powering 36 actively cooled triple-junction cells at 1200x concentration (geometric). The measured end-to-end system conversion efficiency is 28%, including the parasitic loss of the active cooling system. Efficiency ~32% is projected for the next system.