129 research outputs found
Microbial community analysis of Lake Chillisquaque, a small water system in Central Pennsylvania
Cyanobacteria are photosynthetic organisms that require the absorption of light for the completion of photosynthesis. Cyanobacteria can use a variety of wavelengths of light within thevisible light spectrum in order to harvest energy for this process. Many species of cyanobacteria have light-harvesting proteins that specialize in the absorption of a small range of wavelengths oflight along the visual light spectrum; others can undergo complementary chromatic adaptation and alter these light-harvesting proteins in order to absorb the wavelengths of light that are mostavailable in a given environment. This variation in light-harvesting phenotype across cyanobacteria leads to the utilization of environmental niches based on light wavelength availability. Furthermore, light attenuation along the water column in an aquatic system also leads to the formation of environmental niches throughout the vertical water column. In order to better understand these niches based on light wavelength availability, we studied the compositionof cyanobacterial genera at the surface and depth of Lake Chillisquaque at three time points throughout the year: September 2009, May 2010, and July 2010. We found that cyanobacterialgenera composition changes throughout the year as well as with physical location in the water column. Additionally, given the light attenuation noted throughout the Lake Chillisquaque, we are able to conclude that light is a major selective factor in the community composition of Lake Chillisquaque
Community Adaptation to Flooding in a Changing Climate: Municipal Officials’ Actions Decision-Making and Barriers
CaRDI Research & Policy Brief Issue 5
Utility of Direct Pancreatic Function Testing in Children
OBJECTIVES: Exocrine pancreatic insufficiency (EPI) can have a significant impact on a child's growth and nutrition. Our aim was to evaluate the utility of direct endoscopic pancreatic function testing (ePFT) in pediatrics. METHODS: A single-center retrospective chart review was performed of children who underwent ePFT from December 2007 through February 2015. Endoscopic pancreatic function testings were performed by 1 of 2 methods: (1) intravenous cholecystokinin, followed by the collection of a single duodenal aspirate at 10 minutes, or (2) intravenous cholecystokinin or secretin, followed by the collection of 3 duodenal aspirates at a 5, 10, and 15 minutes. Samples were tested for pH and enzyme activities. RESULTS: A total of 508 ePFTs were performed (481 single-sample tests, 27 multiple-sample tests). Based on the multiple-sample group, enzyme levels for chymotrypsin, amylase, and lipase peaked at 5 minutes, followed by a decrease in activity over time. Exocrine pancreatic sufficiency was identified in 373 (73.4%) and EPI in 93 (18.3%). Exocrine pancreatic sufficiency analysis found all pancreatic enzyme activities significantly increase with age: trypsin, chymotrypsin, amylase, and lipase, (P < 0.05). CONCLUSIONS: Endoscopic pancreatic function testing can be used in the evaluation of EPI in children. Normative data suggest that pancreatic enzyme activities mature with age
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Prediction of vascular invasion using a 7-point scale computed tomography grading system in adrenal tumors in dogs
Background: Previous studies evaluating the accuracy of computed tomography (CT) in detecting caudal vena cava (CVC) invasion by adrenal tumors (AT) used a binary system and did not evaluate for other vessels. Objective: Test a 7-point scale CT grading system for accuracy in predicting vascular invasion and for repeatability among radiologists. Build a decision tree based on CT criteria to predict tumor type. Methods: Retrospective observational cross-sectional case study. Abdominal CT studies were analyzed by 3 radiologists using a 7-point CT grading scale for vascular invasion and by 1 radiologist for CT features of AT. Animals: Dogs with AT that underwent adrenalectomy and had pre- and postcontrast CT. Results: Ninety-one dogs; 45 adrenocortical carcinomas (50%), 36 pheochromocytomas (40%), 9 adrenocortical adenomas (10%) and 1 unknown tumor. Carcinoma and pheochromocytoma differed in pre- and postcontrast attenuation, contralateral adrenal size, tumor thrombus short- and long-axis, and tumor and thrombus mineralization. A decision tree was built based on these differences. Adenoma and malignant tumors differed in contour irregularity. Probability of vascular invasion was dependent on CT grading scale, and a large equivocal zone existed between 3 and 6 scores, lowering CT accuracy to detect vascular invasion. Radiologists' agreement for detecting abnormalities (evaluated by chance-corrected weighted kappa statistics) was excellent for CVC and good to moderate for other vessels. The quality of postcontrast CT study had a negative impact on radiologists' performance and agreement. Conclusions and Clinical Importance: Features of CT may help radiologists predict AT type and provide probabilistic information on vascular invasion
Evidence that the negative BOLD response is neuronal in origin: a simultaneous EEG–BOLD–CBF study in humans
Unambiguous interpretation of changes in the BOLD signal is challenging because of the complex neurovascular coupling that translates changes in neuronal activity into the subsequent haemodynamic response. In particular, the neurophysiological origin of the negative BOLD response (NBR) remains incompletely understood. Here, we simultaneously recorded BOLD, EEG and cerebral blood flow (CBF) responses to 10 s blocks of unilateral median nerve stimulation (MNS) in order to interrogate the NBR. Both negative BOLD and negative CBF responses to MNS were observed in the same region of the ipsilateral primary sensorimotor cortex (S1/M1) and calculations showed that MNS induced a decrease in the cerebral metabolic rate of oxygen consumption (CMRO2) in this NBR region. The ∆CMRO2/∆CBF coupling ratio (n) was found to be significantly larger in this ipsilateral S1/M1 region (n = 0.91 ± 0.04, M = 10.45%) than in the contralateral S1/M1 (n = 0.65 ± 0.03, M = 10.45%) region that exhibited a positive BOLD response (PBR) and positive CBF response, and a consequent increase in CMRO2 during MNS. The fMRI response amplitude in ipsilateral S1/M1 was negatively correlated with both the power of the 8–13 Hz EEG mu oscillation and somatosensory evoked potential amplitude. Blocks in which the largest magnitude of negative BOLD and CBF responses occurred therefore showed greatest mu power, an electrophysiological index of cortical inhibition, and largest somatosensory evoked potentials. Taken together, our results suggest that a neuronal mechanism underlies the NBR, but that the NBR may originate from a different neurovascular coupling mechanism to the PBR, suggesting that caution should be taken in assuming the NBR simply represents the neurophysiological inverse of the PBR
Historical Institutionalism and Foreign Policy Analysis: The Origins of the National Security Council Revisited
Global signal modulation of single-trial fMRI response variability: effect on positive vs negative BOLD response relationship
In functional magnetic resonance imaging (fMRI), the relationship between positive BOLD responses (PBRs) and negative BOLD responses (NBRs) to stimulation is potentially informative about the balance of excitatory and inhibitory brain responses in sensory cortex. In this study, we performed three separate experiments delivering visual, motor or somatosensory stimulation unilaterally, to one side of the sensory field, to induce PBR and NBR in opposite brain hemispheres. We then assessed the relationship between the evoked amplitudes of contralateral PBR and ipsilateral NBR at the level of both single-trial and average responses. We measure single-trial PBR and NBR peak amplitudes from individual time-courses, and show that they were positively correlated in all experiments. In contrast, in the average response across trials the absolute magnitudes of both PBR and NBR increased with increasing stimulus intensity, resulting in a negative correlation between mean response amplitudes. Subsequent analysis showed that the amplitude of single-trial PBR was positively correlated with the BOLD response across all grey-matter voxels and was not specifically related to the ipsilateral sensory cortical response. We demonstrate that the global component of this single-trial response modulation could be fully explained by voxel-wise vascular reactivity, the BOLD signal standard deviation measured in a separate resting-state scan (resting state fluctuation amplitude, RSFA). However, bilateral positive correlation between PBR and NBR regions remained. We further report that modulations in the global brain fMRI signal cannot fully account for this positive PBR-NBR coupling and conclude that the local sensory network response reflects a combination of superimposed vascular and neuronal signals. More detailed quantification of physiological and noise contributions to the BOLD signal is required to fully understand the trial-by-trial PBR and NBR relationship compared with that of average responses
Smoking onset and the time-varying effects of self-efficacy, environmental smoking, and smoking-specific parenting by using discrete-time survival analysis
This study examined the timing of smoking onset during mid- or late adolescence and the time-varying effects of refusal self-efficacy, parental and sibling smoking behavior, smoking behavior of friends and best friend, and parental smoking-specific communication. We used data from five annual waves of the ‘Family and Health’ project. In total, 428 adolescents and their parents participated at baseline. Only never smokers were included at baseline (n = 272). A life table and Kaplan–Meier survival curve showed that 51% of all adolescents who did not smoke at baseline did not start smoking within 4 years. The risk for smoking onset during mid- or late adolescence is rather stable (hazard ratio between 16 and 19). Discrete-time survival analyses revealed that low refusal self-efficacy, high frequency of communication, and sibling smoking were associated with smoking onset one year later. No interaction effects were found. Conclusively, the findings revealed that refusal self-efficacy is an important predictor of smoking onset during mid- or late adolescence and is independent of smoking-specific communication and smoking behavior of parents, siblings, and (best) friend(s). Findings emphasize the importance of family prevention programs focusing on self-efficacy skills
Toward an Empirical Concept of Group
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93537/1/j.1468-5914.1993.tb00543.x.pd
A whey protein-based multi-ingredient nutritional supplement stimulates gains in lean body mass and strength in healthy older men: A randomized controlled trial
Protein and other compounds can exert anabolic effects on skeletal muscle, particularly in conjunction with exercise. The objective of this study was to evaluate the efficacy of twice daily consumption of a protein-based, multi-ingredient nutritional supplement to increase strength and lean mass independent of, and in combination with, exercise in healthy older men. Forty-nine healthy older men (age: 73 ± 1 years [mean ± SEM]; BMI: 28.5 ± 1.5 kg/m2) were randomly allocated to 20 weeks of twice daily consumption of either a nutritional supplement (SUPP; n = 25; 30 g whey protein, 2.5 g creatine, 500 IU vitamin D, 400 mg calcium, and 1500 mg n-3 PUFA with 700 mg as eicosapentanoic acid and 445 mg as docosahexanoic acid); or a control (n = 24; CON; 22 g of maltodextrin). The study had two phases. Phase 1 was 6 weeks of SUPP or CON alone. Phase 2 was a 12 week continuation of the SUPP/CON but in combination with exercise: SUPP + EX or CON + EX. Isotonic strength (one repetition maximum [1RM]) and lean body mass (LBM) were the primary outcomes. In Phase 1 only the SUPP group gained strength (Σ1RM, SUPP: +14 ± 4 kg, CON: +3 ± 2 kg, P < 0.001) and lean mass (LBM, +1.2 ± 0.3 kg, CON: -0.1 ± 0.2 kg, P < 0.001). Although both groups gained strength during Phase 2, upon completion of the study upper body strength was greater in the SUPP group compared to the CON group (Σ upper body 1RM: 119 ± 4 vs. 109 ± 5 kg, P = 0.039). We conclude that twice daily consumption of a multi-ingredient nutritional supplement increased muscle strength and lean mass in older men. Increases in strength were enhanced further with exercise training
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