Are medical students happy despite unhappy conditions: a qualitative exploration of medical student cohorts during disruptive conditions.

BACKGROUND: Shortly after the World Health Organization declared the SARS-CoV-2 outbreak a worldwide pandemic, medical school governing bodies issued guidance recommending pausing clinical rotations. Prior to the availability of COVD-19 vaccines, many schools implemented exclusively online curriculums in the didactic and clinical years. These unprecedented events and paradigm changes in medical education could contribute to trainee burnout, wellness, and mental health. METHODS: This single-institution study interviewed first, second, and third-year medical students from a medical school in the southwestern United States. A semi-structured interview was conducted with paper-based Likert scale questions rating perceived happiness were administered both at the time of the interview and one year later in order to understand how their student experience and happiness were impacted. In addition, we asked participants to describe any major life events they experienced since the first interview. RESULTS: Twenty-seven volunteers participated in the original interview. Twenty-four from the original cohort participated in the one-year follow-up. Happiness as a sense of self and who you "should be" was challenged during the pandemic and changes in happiness over time were not systematic across classes. Stress was caused not only by the pandemic which was experienced by all, but by a tripartite state of individual circumstances, academic workload requirements, and the world at large. Primary themes from the interviews were clustered around the individual, learner, and future professional levels and focused on the primacy of relationships, emotional wellness, stress management, professional identity, and impacts of educational disruptions. These themes created risk factors for developing imposter syndrome. Students demonstrated resiliency across cohorts and were able to utilize a variety of strategies to achieve and maintain both physical and mental health, but the primacy of relationships both personally and professionally was noted. CONCLUSION: Medical students' identities as individual persons, a learner, and future medical professionals were all impacted by the pandemic. The results from this study suggest that the COVID-19 pandemic and changes in the learning format and environment may create a new risk factor in the development of imposter syndrome. There is also an opportunity to re-consider resources to achieve and maintain wellness during a disrupted academic environment.

Motivation of UK graduate students in education: self-compassion moderates pathway from extrinsic motivation to intrinsic motivation.

Academic motivation is recognised as a key factor for academic success and wellbeing. Highly motivated students actively engage with academic activities and maintain good wellbeing. Despite the importance of motivation in education, its relationship with engagement and wellbeing remains to be evaluated. Accordingly, this study explored the relationships between motivation, engagement, self-criticism and self-compassion among UK education postgraduate students. Of 120 postgraduate students approached, 109 completed three self-report scales regarding those constructs. Correlation, regression and moderation analyses were performed. Intrinsic and extrinsic motivation were positively associated with engagement, whereas amotivation was negatively associated with it. Engagement positively predicted intrinsic motivation. Self-criticism and self-compassion moderated the pathway from extrinsic motivation to intrinsic motivation: higher self-criticism weakened the pathway, while higher self-compassion strengthened it. Findings suggest the importance of engagement in relation to cultivating intrinsic motivation of education students. Moreover, enhancing self-compassion and reducing self-criticism can help transfer extrinsic to intrinsic motivation.

Early [18]FDG PET/CT scan predicts tumor response in head and neck squamous cell cancer patients treated with erlotinib adjusted per smoking status.

Translational Relevance: Evaluation of targeted therapies is urgently needed for the majority of patients with metastatic/recurrent head and neck squamous cell carcinoma (HNSCC) who progress after immunochemotherapy. Erlotinib, a targeted inhibitor of epidermal growth factor receptor pathway, lacks FDA approval in HNSCC due to inadequate tumor response. This study identifies two potential avenues to improve tumor response to erlotinib among patients with HNSCC. For the first time, this study shows that an increased erlotinib dose of 300 mg in smokers is well-tolerated and produces similar plasma drug concentration as the regular dose of 150 mg in non-smokers, with increased study-specific defined tumor response. The study also highlights the opportunity for improved patient selection for erlotinib treatment by demonstrating that early in-treatment [18]FDG PET/CT is a potential predictor of tumor response, with robust statistical correlations between metabolic changes on early in-treatment PET (4-7 days through treatment) and anatomic response measured by end-of-treatment CT. Purpose: Patients with advanced HNSCC failing immunochemotherapy have no standard treatment options. Accelerating the investigation of targeted drug therapies is imperative. Treatment with erlotinib produced low response rates in HNSCC. This study investigates the possibility of improved treatment response through patient smoking status-based erlotinib dose optimization, and through early in-treatment [18]FDG PET evaluation to differentiate responders from non-responders. Experimental design: In this window-of-opportunity study, patients with operable HNSCC received neoadjuvant erlotinib with dose determined by smoking status: 150 mg (E150) for non-smokers and 300 mg (E300) for active smokers. Plasma erlotinib levels were measured using mass spectrometry. Patients underwent PET/CT before treatment, between days 4-7 of treatment, and before surgery (post-treatment). Response was measured by diagnostic CT and was defined as decrease in maximum tumor diameter by ≥ 20% (responders), 10-19% (minimum-responders), and < 10% (non-responders). Results: Nineteen patients completed treatment, ten of whom were smokers. There were eleven responders, five minimum-responders, and three non-responders. Tumor response and plasma erlotinib levels were similar between the E150 and E300 patient groups. The percentage change on early PET/CT and post-treatment PET/CT compared to pre-treatment PET/CT were significantly correlated with the radiologic response on post-treatment CTs: R=0.63, p=0.0041 and R=0.71, p=0.00094, respectively. Conclusion: This pilot study suggests that early in-treatment PET/CT can predict response to erlotinib, and treatment with erlotinib dose adjusted according to smoking status is well-tolerated and may improve treatment response in HNSCC. These findings could help optimize erlotinib treatment in HNSCC and should be further investigated. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT00601913, identifier NCT00601913.

Mental Health Shame, Caregiver Identity, and Self-Compassion in UK Education Students.

Although students in education have high rates of mental health problems, many of them do not ask for help, which can exacerbate their symptoms. One reason for their low help-seeking is shame associated with mental health problems. As education students aspire to provide care for children, they may feel ashamed to care for themselves, as the role identity theory suggests. Self-compassion is reported to reduce shame and mental health problems. This study explored the relationships between mental health problems, mental health shame, self-compassion, and caregiver identity among UK education students. One hundred and nine postgraduate students completed four self-report scales regarding those constructs. Correlation and regression analyses were performed. Mental health problems were positively associated with shame and identity, and negatively associated with self-compassion. Self-compassion was the only significant predictor of mental health problems. Findings will help educators and education students to develop effective approaches for their mental health problems.

Population-Based HIV Impact Assessments Survey Methods, Response, and Quality in Zimbabwe, Malawi, and Zambia.

BACKGROUND: The population-based HIV impact assessment (population-based HIV impact assessments) surveys are among the first to estimate national adult HIV incidence, subnational prevalence of viral load suppression, and pediatric HIV prevalence. We summarize the survey methods implemented in Zimbabwe, Malawi, and Zambia, as well as response rates and quality metrics. METHODS: Each cross-sectional, household-based survey used a 2-stage cluster design. Survey preparations included sample design, questionnaire development, tablet programming for informed consent and data collection, community mobilization, establishing a network of satellite laboratories, and fieldworker training. Interviewers collected demographic, behavioral, and clinical information using tablets. Blood was collected for home-based HIV testing and counseling (HBTC) and point-of-care CD4+ T-cell enumeration with results immediately returned. HIV-positive blood samples underwent laboratory-based confirmatory testing, HIV incidence testing, RNA polymerase chain reaction (viral load), DNA polymerase chain reaction (early infant diagnosis), and serum antiretroviral drug detection. Data were weighted for survey design, and chi square automatic interaction detection-based methods were used to adjust for nonresponse. RESULTS: Each survey recruited a nationally representative, household-based sample of children and adults over a 6-10-month period in 2015 and 2016. Most (84%-90%) of the 12,000-14,000 eligible households in each country participated in the survey, with 77%-81% of eligible adults completing an interview and providing blood for HIV testing. Among eligible children, 59%-73% completed HIV testing. Across the 3 surveys, 97.8% of interview data were complete and had no errors. CONCLUSION: Conducting a national population-based HIV impact assessment with immediate return of HIV and other point-of-care test results was feasible, and data quality was high.

HIV Incidence by Male Circumcision Status From the Population-Based HIV Impact Assessment Surveys-Eight Sub-Saharan African Countries, 2015-2017.

BACKGROUND: Male circumcision (MC) offers men lifelong partial protection from heterosexually acquired HIV infection. The impact of MC on HIV incidence has not been quantified in nationally representative samples. Data from the population-based HIV impact assessments were used to compare HIV incidence by MC status in countries implementing voluntary medical MC (VMMC) programs. METHODS: Data were pooled from population-based HIV impact assessments conducted in Eswatini, Lesotho, Malawi, Namibia, Tanzania, Uganda, Zambia, and Zimbabwe from 2015 to 2017. Incidence was measured using a recent infection testing algorithm and analyzed by self-reported MC status distinguishing between medical and nonmedical MC. Country, marital status, urban setting, sexual risk behaviors, and mean population HIV viral load among women as an indicator of treatment scale-up were included in a random-effects logistic regression model using pooled survey weights. Analyses were age stratified (15-34 and 35-59 years). Annualized incidence rates and 95% confidence intervals (CIs) and incidence differences were calculated between medically circumcised and uncircumcised men. RESULTS: Men 15-34 years reporting medical MC had lower HIV incidence than uncircumcised men [0.04% (95% CI: 0.00% to 0.10%) versus 0.34% (95% CI: 0.10% to 0.57%), respectively; P value = 0.01]; whereas among men 35-59 years, there was no significant incidence difference [1.36% (95% CI: 0.32% to 2.39%) versus 0.55% (95% CI: 0.14% to 0.67%), respectively; P value = 0.14]. DISCUSSION: Medical MC was associated with lower HIV incidence in men aged 15-34 years in nationally representative surveys in Africa. These findings are consistent with the expected ongoing VMMC program impact and highlight the importance of VMMC for the HIV response in Africa.

Improving the benefits of HIV testing and referrals in large household surveys through active linkages to care: lessons and recommendations from the Namibia population-based HIV impact assessment (NAMPHIA), 2017.

In household-based surveys that include rapid HIV testing services (HTS), passive referral systems that give HIV-positive participants information about how and where to access ART but minimal follow-up support from survey staff may result in suboptimal linkage. In the 2017 Namibia Population-based HIV Impact Assessment (NAMPHIA), we piloted a system of active linkage to care and ART (ALCART) that utilized the infrastructure of existing community-based partner organizations (CBPOs). All HIV-positive participants age 15-64 years not on ART were given standard passive referrals to ART plus the option to participate in ALCART. Cases were assigned to CBPOs in participants' localities. Healthcare workers from the CBPO's contacted cases and facilitated their linkage to facility-based ART. A total of 510 participants were eligible and consented to ALCART. The majority were new diagnoses (80.8%), while the remainder were previously diagnosed but not on ART (19.2%). Of the 510, 473 (92.7%) were successfully linked into care. Of these, all but one initiated ART. Our ALCART system used existing CBPOs and contributed to >90% linkage-to-care and >99% ART-initiation among linked participants in a large, nationally-representative survey. This approach can be used to improve the potential benefits of HTS in other large population-based surveys.

Is virtual clinic follow-up of hip and knee joint replacement acceptable to patients and clinicians? A sequential mixed methods evaluation.

Objective: To evaluate the acceptability to key stake holders of a newly introduced virtual clinic follow-up pathway for hip and knee joint replacement. Design: A service evaluation comprising a questionnaire sent electronically to 115 patients and interviews with 10 individuals. Setting: A newly introduced virtual clinic follow-up pathway for hip and knee replacement patients in a district general hospital. Participants: The electronic questionnaire was distributed to all patients treated under the virtual clinic service over a 5-month period (n=115). Purposive sampling from volunteers among respondents, leading to semi-structured interviews with eight patients. Two orthopaedic consultants were also interviewed. Intervention: Consultant review of web-based patient reported outcome measures and digital radiographs, with feedback to patients via letter, replacing face-to-face outpatient appointments for the follow-up of hip and knee joint replacement. Results: The response rate to the questionnaire was 40%. 44% indicated they would prefer a virtual appointment over a face-to-face consultation in future. The most common word in the free text comments was 'good' (n=107).Seven main themes were identified from the patient interviews: patient understanding and expectations, patient confidence, patient voice, managing deterioration of condition, patient benefit, patient satisfaction using technology and navigating the website.Two main themes were identified from the staff interviews: the adapting patient pathway and project management.Combined analysis elucidated that patients who were doing well liked the 'click and go' approach but those with problems were concerned about how to report these and were therefore less satisfied. Conclusion: The virtual clinic process appears to be well accepted by both patients and clinicians. However, appropriate patient selection and clear pathways of communication to address patient concerns are pivotal to success.

Non-operative management, supported by self-monitoring using web-based patient reported outcome measures (PROMs), in knee osteoarthritis.

Despite being straightforward to collect and key to providing patient-centred, individualised care, the routine use of patient reported outcome measures (PROMs) remains limited in the National Health Service. Herein is described the case of a 69-year-old woman who presented to secondary care with osteoarthritis. Web-based PROMs were used to track the patient's symptoms and function. Lifestyle changes were recommended to manage the osteoarthritis. Monitoring enabled the patient to take control of her disease management. Two years later, she continues to manage her knee symptoms conservatively, recording progress by using a web-based system. This case illustrates how web-based PROMs can be used to support conservative management of knee osteoarthritis by both empowering patients and minimising the burden on secondary care outpatient services.

Tracking a painful episode after a joint replacement using patient-reported outcome measures (PROMs).

Patient-reported outcome measures (PROMs) are an important tool in measuring the benefit of a surgery for patients and for clinicians. The results of such assessment tools can be used to monitor patient progress or initiate intervention. The scores also provide a reproducible evaluation of functional recovery and well-being after surgery. We report the case of a 68-year-old woman who underwent left unicondylar knee replacement in November 2011 followed by right unicondylar knee replacement in April 2012. Prospective, web-based electronic PROMs were used preoperatively and every 6-12 months postoperatively to monitor the improvement in pain and function symptoms. These outcome measures were beneficial in helping to monitor an episode of new pain in her left knee, without requiring invasive or extensive investigation.

Patient-reported outcome measures (PROMs): enhancing decision making and follow-up.

A case presentation of patient undergoing elective total knee replacement. Patient-reported outcome measures prospectively collected electronically pre and postoperatively allowed real-time review, aiding follow-up and reducing the need for clinical, face-to-face follow-up.

Performance of EQ-5D, howRu and Oxford hip & knee scores in assessing the outcome of hip and knee replacements.

BACKGROUND: We aimed to compare the performance of EQ-5D-3 L and howRu, which are short generic patient-reported outcome measures (PROMs), in assessing the outcome of hip and knee replacements, using the Oxford Hip Score (OHS) and the Oxford Knee Scores (OKS) for comparison. METHODS: Outcome was assessed as the difference between pre-surgery and 6-month post-surgery scores. We used a large sample from the NHS PROMs database, which used EQ-5D-3 L, and a small cohort of patients having the same operations collected by MyClinicalOutcomes (MCO), which used howRu. Both cohorts completed the OHS (hips) or the OKS (knees). RESULTS: The change (outcome) between pre-op and post-op scores as measured by howRu was greater than that measured by EQ-5D, relative to that measured by OHS or OKS. For hip replacements, the correlation for change measured by howRu and OHS was r = 0.77 (0.66-0.85). The corresponding correlation for change measured by EQ-5D Index and OHS was r = 0.64 (0.63-0.64). For knee replacements the correlation between change in howRu and OKS was r = 0.86 (0.75-0.92); between EQ-5D Index and OKS r = 0.59 (0.58-0.60). CONCLUSIONS: For hip and knee replacement, the outcome measured by howRu was more highly correlated with that measured by the condition-specific Oxford Hip and Knee Scores than were EQ-5D Index or EQ-VAS. The magnitude of change before and after surgery was also greater.

The Relationship Between Perceptions of Wilderness Character and Attitudes Toward Management Intervention to Adapt Biophysical Resources to a Changing Climate and Nature Restoration at Sequoia and Kings Canyon National Parks.

In a recent national survey of federal wilderness managers, respondents identified the high priority need for scientific information about public attitudes toward biophysical intervention to adapt to climate change and attitudes of the public toward restoration of natural conditions. In a survey of visitors to one National Park wilderness in California, visitors revealed that they largely do not support biophysical intervention in wilderness to mitigate the effects of climate change, but broad support for activities that restore natural conditions exists. In an attempt to understand how these attitudes vary among visitors, it was found that those visitors who most value naturalness aspects of wilderness character also most positively support restoration and are most negative toward climate change intervention practices. More information about visitor-defined wilderness character attributes is needed and strategic planning to guide intervention decisions and restoration should be a priority. In this study, it was found that wilderness character is largely defined by visitors based on its wildness attributes, which include natural sounds, low density of people, pure water, clean air, and the presence of humans substantially unnoticeable.

Optimized protocol for cryopreservation of human eggs improves developmental competence and implantation of resulting embryos.

BACKGROUND: Successful egg cryopreservation has many potential benefits to a variety of patients. However, a superior standard protocol describing all aspects of oocyte cryopreservation has not yet been identified. Oocyte cryopreservation is still a technical challenge for many infertility clinics. To maintain satisfactory clinical outcomes, there is a need to develop an easy to use, yet efficient laboratory protocol. The present study was designed to examine if human embryos resulting from eggs frozen with an optimized vitrification protocol have similar developmental competence as those from fresh eggs. METHODS: Twenty recipients received donated eggs vitrified with a protocol in which short exposure time to the vitrification solution was used and 23 recipients received donated eggs and 6 patients had their own eggs vitrified with a modified protocol in which long exposure time to the vitrification solution was used. After warming, egg survival, fertilization, cleavage, blastocyst formation, clinical pregnancy and implantation rates were compared. The developmental competence of eggs vitrified with the optimized protocol was further compared with fresh eggs donated from the same donors. RESULTS: There was no difference in the oocyte survival, fertilization, cleavage, clinical pregnancy or implantation rates between the short and long protocol groups. However, blastocyst formation rate was significantly (P < 0.001) higher in the long protocol group (50.8%) than that in short protocol group (26.5%), resulting in more blastocysts being transferred and frozen. When frozen eggs vitrified with long protocol and fresh eggs from the same donors (12) were compared in 39 recipients, no differences were observed in terms of fertilization (86.4 vs 80.1%), blastocyst formation (50.0 vs 59.2%), clinical pregnancy (63.2 vs 60.0%) and implantation (41.7 vs 44.7%) rates. Four out of 6 patients had ongoing pregnancy after transfer of embryos from their own frozen eggs with a 46.2% implantation rate. CONCLUSIONS: These results indicate that blastocyst development is an appropriate measure for egg survival after cryopreservation and frozen eggs have similar developmental potential as fresh eggs if they are frozen with an optimized method.

DNA microarray reveals that high proportions of human blastocysts from women of advanced maternal age are aneuploid and mosaic.

Trophectoderm (TE) biopsy and DNA microarray have become the new technologies for preimplantation genetic diagnosis in humans. In this study, we comprehensively examined aneuploid formation in human blastocysts produced in vitro with microarray and investigated the clinical outcome after transfer of euploid embryos. Biopsied cells from either TE or inner cell mass (ICM) were processed for microarray to examine the errors in 23 pairs of chromosomes and the consistency between TE and ICM. It was found that 56.6% of blastocysts were aneuploid. Further analysis indicated that 62.3% of aneuploid blastocysts had single and 37.7% had multiple chromosomal abnormalities. Chromosome errors could occur in any chromosome, but errors in chromosome 21 accounted for the most (11.3%) among the 23 pairs of chromosomes. Transfer of array-screened blastocysts produced high pregnancy (70.2%) and implantation (63.5%) rates. Microarray of TE and ICM cells in the same blastocysts revealed that high proportions of aneuploid blastocysts (69.2%) were mosaic, including aneuploid TE and euploid ICM, inconsistent anomalies between ICM and TE, or euploid TE cells and aneuploid ICM in the same blastocyst. These results indicate that high proportions of human blastocysts produced in vitro from women of advanced maternal age are aneuploid and mosaic. Errors can occur in any of the 23 pairs of chromosomes in human blastocysts. Biopsy from TE in blastocysts does not exactly predict the chromosomal information in ICM if the embryos are aneuploid. Some mosaic blastocysts have euploid ICM, which may indicate important differentiate mechanism(s) of human preimplantation embryos.

Cetrorelix lowers premature luteinization rate in gonadotropin ovulation induction-intrauterine insemination cycles: a randomized-controlled clinical trial.

Attempting to compare the rates of premature luteinization (PL), clinical pregnancy, and cycle cancellation in ovulation induction-intrauterine insemination (OI-IUI) cycles with and without the GnRH antagonist, cetrorelix, a randomized-controlled trial was undertaken in which patients were randomized to one of two OI-IUI protocols. Those in the cetrorelix arm showed a significantly reduced rate of PL and no change in clinical pregnancy or cycle cancellation rate, leading to the conclusion that GnRH antagonists can decrease the rate of PL, but appear to have no effect on pregnancy or cycle cancellation in gonadotropin OI-IUI cycles.

Burden of malignancy after a primary skin cancer: recurrence, multiple skin cancers and second primary cancers.

The current paper summarizes relevant recent research on the high risk of recurrence, multiple skin cancers and second primary cancers in the growing number of people with a history of skin cancer; the ultimate purpose is to better assess the burden of malignancy following skin cancer. A number of challenges exist in identifying and tracking both melanoma and non-melanoma skin cancer (NMSC) cases. Most jurisdictions do not routinely track NMSC cases and, even if they do, it is customary to only include the first diagnosis. There are variable rules for counting multiple melanoma cancers, and recurrences are not considered for either major type of skin cancer. Applying insights from recent studies of this issue to Canadian cancer statistics would increase reported diagnoses of NMSC by about 26% and melanoma by 10% in this country. This approach to a fuller assessment of the burden of skin cancers has been called a "diagnosis-based incidence approach" as compared with a "patient-based incidence approach". A further issue that is not usually taken into account when assessing the burden of skin cancers is the 20% to 30% elevated risk of noncutaneous second primary cancers following a primary skin tumour. In summary, individuals with skin cancer are subject to a high risk of recurrence, multiple skin cancers and second primary cancers. This burden should be a special concern in the large and growing pool of individuals with a history of skin cancer, as well as among prevention planners.

Non-union following bilateral simultaneos Ganz trochanteric osteotomy.

Between January 2003 and December 2004, 13 patients underwent bilateral resurfacing arthroplasty via a Ganz trochanteric osteotomy. This bilateral group was mobilised fully weight-bearing with crutches. During the same period 139 Ganz trochanteric osteotomies were performed for unilateral hip resurfacing. These patients were mobilised with crutches, weight-bearing up to 10 kg on the operated leg. Nine osteotomies (32%) in the bilateral group subsequently developed a symptomatic non-union requiring revision of fixation. This compares with 10 patients (7%) in the unilateral group. Applying the Fisher's exact test, the difference reached significance (P=0.0004). In two patients a second revision was required to achieve union. In one patient, revision of trochanteric fixation precipitated a deep infection. Protected weight-bearing following a Ganz trochanteric osteotomy is important to the success of the procedure. Simultaneous bilateral hip arthroplasty through a Ganz approach should be avoided. If it is undertaken, we recommend that patients should be non weight-bearing for 6 weeks following surgery. Non-union following a Ganz trochanteric osteotomy for arthroplasty carries a significant morbidity.

Early failure of the Dual coat Cormet 2000 metal on metal acetabular component.

We report a 10% failure rate for aseptic loosening and overall revision rate of 15% at 5 years mean follow up in 190 patients using the Cormet 2000 Dual coat acetabular component. Between 2001 and 2004, the original Dual coat component was used in our region by 4 experienced arthroplasty surgeons. 142 were used with resurfacing heads. The average age was 54 and 99 were male. Revision for aseptic loosening was required in 20 cups (10%) at a mean interval of 23 months including five within 2 months. Persistent groin pain was seen in a further three patients who have declined further surgery. Failure of the backing of this implant to integrate reliably with bone has led to an unacceptably high early loosening rate of the original design which was phased out in 2003.

Factors influencing the persistence of fecal Bacteroides in stream water.

Laboratory microcosm experiments were used to assess the effects of environmental parameters on the persistence of the Bacteroides 16S rRNA genes derived from equine fecal samples in stream water to investigate the utility of Bacteroides spp. as fecal indicator organisms. Quantitative real-time polymerase chain reaction (qPCR) was used to measure gene concentrations over time with treatments designed to compare filtered vs. unfiltered stream water, fecal aggregate size, initial fecal concentrations, and water temperatures. Comparison of Bacteroides16S rRNA genes/mL in microcosms constructed with unfiltered stream water and filtered stream water indicated that stream water filtration to remove indigenous microorganisms followed by temperature had the largest effects on gene persistence. First-order exponential decay functions were fitted to the data from each microcosm constructed using unfiltered stream water, and the decay constants (k) ranged from 0.0071 h(-1) in the microcosms incubated at 5 degrees C to 0.0336 h(-1) in a set of microcosms incubated at 25 degrees C. Analysis of k calculated from the 10 experimental treatments indicated that k is more highly correlated to temperature than initial Bacteroides 16S rRNA gene starting concentrations. The equation resulting from graphing k (as the dependent variable) vs. temperature (as the independent variable) best fit a peak, Gaussian, 3 parameter function with a maximum decay at 30 degrees C, a r(2) of 0.83 and all parameters were significant (P < 0.0015). Thus this data suggest that factors that reduce biological activity, such as physical removal of stream microorganisms by filtration and low temperature, result in slower Bacteroides 16S rRNA gene decay.