74 research outputs found
Coupled CFD-CAA approach for rotating systems
We present a recently developed computational scheme for the numerical simulation of ïŹow induced sound for rotating systems. Thereby, the ïŹow is fully resolved in time by utilizing a DES (Detached Eddy Simulation) turbulance model and using an arbitrary mesh interface scheme for connecting rotating and stationary domains. The acoustic ïŹeld is modeled by a perturbation ansatz resulting in a convective wave equation based on the acoustic scalar potential and the substational time derivative of the incompressible ïŹow pressure as a source term. We use the Finite-Element (FE) method for solving the convective wave equation and apply a Nitsche type mortaring at the interface between rotating and stationary domains. The whole scheme is applied to the numerical computation of a side channel blower
Calanus finmarchicus seasonal cycle and diapause in relation to gene expression, physiology, and endogenous clocks: Calanus finmarchicus seasonal rhythmicity
The copepod Calanus finmarchicus plays a crucial role in the north Atlantic food web. Its seasonal life cycle involves reproduction and development in surface waters before overwintering in diapause at depth. Although diapause has been studied for more than a century, the factors responsible for the initiation and termination of it are still unclear. Endogenous clocks have been identified as potent tools for photoperiod measurement and seasonal rhythmicity in many terrestrial species, but knowledge of these remains scarce in the marine realm. Focusing on the dominant CV copepodid stage, we sampled a population of C. finmarchicus from a Scottish sea loch to characterize population dynamics, several physiological parameters, and diel and seasonal expression rhythms of 35 genes representing different metabolic pathways, including the circadian clock machinery. This generated a detailed overview of the seasonal cycle of C. finmarchicus including the most extensive field dataset on circadian clock gene expression in a marine species to date. Gene expression patterns revealed distinct gene clusters upregulated at different phases of the copepod's seasonal cycle. While diel clock cycling was restricted to the active spring/summer phase, many clock genes exhibited the highest expression during diapause. Our results provide new insights into diapause on physiological and genetic levels. We suggest that photoperiod, in interaction with internal and external factors (lipid content, temperature, food availability) and the endogenous clock mechanism, plays an important role in the timing of diapause in C. finmarchicus
Circadian Clock Involvement in Zooplankton Diel Vertical Migration
Biological clocks are a ubiquitous ancient and adaptive mechanism enabling organisms to anticipate environmental cycles and to regulate behavioral and physiological processes accordingly [1]. Although terrestrial circadian clocks are well understood, knowledge of clocks in marine organisms is still very limited [2, 3, 4, 5]. This is particularly true for abundant species displaying large-scale rhythms like diel vertical migration (DVM) that contribute significantly to shaping their respective ecosystems [6]. Here we describe exogenous cycles and endogenous rhythms associated with DVM of the ecologically important and highly abundant planktic copepod Calanus finmarchicus. In the laboratory, C. finmarchicus shows circadian rhythms of DVM, metabolism, and most core circadian clock genes (clock, period1, period2, timeless, cryptochrome2, and clockwork orange). Most of these genes also cycle in animals assessed in the wild, though expression is less rhythmic at depth (50â140 m) relative to shallow-caught animals (0â50 m). Further, peak expressions of clock genes generally occurred at either sunset or sunrise, coinciding with peak migration times. Including one of the first field investigations of clock genes in a marine species [5, 7], this study couples clock gene measurements with laboratory and field data on DVM. While the mechanistic connection remains elusive, our results imply a high degree of causality between clock gene expression and one of the planetâs largest daily migrations of biomass. We thus suggest that circadian clocks increase zooplankton fitness by optimizing the temporal trade-off between feeding and predator avoidance, especially when environmental drivers are weak or absent [8]
Bowel Preparation for Colonoscopy with Sodium Phosphate Solution versus Polyethylene Glycol-Based Lavage: A Multicenter Trial
Background: Adequate bowel preparation is essential for
accurate colonoscopy. Both oral sodium phosphate (NaP) and
polyethylene glycol-based lavage (PEG-ELS) are used predominantly
as bowel cleansing modalities. NaP has gained popularity due to
low drinking volume and lower costs. The purpose of this
randomized multicenter observer blinded study was to compare
three groups of cleansing (NaP, NaP + sennosides, PEG-ELS +
sennosides) in reference to tolerability, acceptance, and
cleanliness. Patient and Methods: 355 outpatients between 18 and
75 years were randomized into three groups (A, B, C) receiving NaP =
A, NaP, and sennosides = B or PEG-ELS and sennosides = C.
Gastroenterologists performing colonoscopies were blinded to the
type of preparation. All patients documented tolerance and adverse
events. Vital signs, premedication, completeness, discomfort, and
complications were recorded. A quality score (0â4) of cleanliness
was generated. Results: The three groups were similar
with regard to age, sex, BMI, indication for colonoscopy, and
comorbidity. Drinking volumes (L) (A = 4.33 + 1.2, B = 4.56 + 1.18, C = 4.93 + 1.71) were in favor of NaP
(P = .005). Discomfort from
ingested fluid was recorded in A = 39.8% (versus C: P = .015),
B = 46.6% (versus C: P = .147), and C = 54.6%. Differences in tolerability and acceptance between the three groups were
statistically not significant. No differences in adverse events
and the cleanliness effects occurred in the three groups (P = .113).
The cleanliness quality scores 0â2 were calculated in A:
77.7%, B: 86.7%, and C: 85.2%. Conclusions:
These data fail to demonstrate significant differences in
tolerability, acceptance, and preparation quality between the
three types of bowel preparation for colonoscopy. Cleansing with
NaP was not superior to PEG-ELS
Exhaled Volatile Organic Compounds during Inflammation Induced by TNF-α in Ventilated Rats
Systemic inflammation alters the composition of exhaled breath, possibly helping clinicians
diagnose conditions such as sepsis. We therefore evaluated changes in exhaled breath of rats given
tumor necrosis factor-alpha (TNF-α). Thirty male Sprague-Dawley rats were randomly assigned
to three groups (n = 10 each) with intravenous injections of normal saline (control), 200 ”g·kgâ1
bodyweight TNF-α (TNF-α-200), or 600 ”g·kgâ1 bodyweight TNF-α (TNF-α-600), and were observed
for 24 h or until death. Animals were ventilated with highly-purified synthetic air to analyze exhaled
air by multicapillary columnâion mobility spectrometry. Volatile organic compounds (VOCs) were
identified from a database. We recorded blood pressure and cardiac output, along with cytokine
plasma concentrations. Control rats survived the 24 h observation period, whereas mean survival
time decreased to 22 h for TNF-α-200 and 23 h for TNF-α-600 rats. Mean arterial pressure decreased in
TNF-α groups, whereas IL-6 increased, consistent with mild to moderate inflammation. Hundreds of
VOCs were detected in exhalome. P-cymol increased by a factor-of-two 4 h after injection of TNF-α-600
compared to the control and TNF-α-200. We found that 1-butanol and 1-pentanol increased in both
TNF-α groups after 20 h compared to the control. As breath analysis distinguishes between two doses
of TNF-α and none, we conclude that it might help clinicians identify systemic inflammatio
Chronic depression: development and evaluation of the luebeck questionnaire for recording preoperational thinking (LQPT)
<p>Abstract</p> <p>Background</p> <p>A standardized instrument for recording the specific cognitive psychopathology of chronically depressed patients has not yet been developed. Up until now, preoperational thinking of chronically depressed patients has only been described in case studies, or through the external observations of therapists. The aim of this study was to develop and evaluate a standardized self-assessment instrument for measuring preoperational thinking that sufficiently conforms to the quality criteria for test theory.</p> <p>Methods</p> <p>The "Luebeck Questionnaire for Recording Preoperational Thinking (LQPT)" was developed and evaluated using a german sample consisting of 30 episodically depressed, 30 chronically depressed and 30 healthy volunteers. As an initial step the questionnaire was subjected to an item analysis and a final test form was compiled. In a second step, reliability and validity tests were performed.</p> <p>Results</p> <p>Overall, the results of this study showed that the LQPT is a useful, reliable and valid instrument. The reliability (split-half reliability 0.885; internal consistency 0.901) and the correlations with other instruments for measuring related constructs (control beliefs, interpersonal problems, stress management) proved to be satisfactory. Chronically depressed patients, episodically depressed patients and healthy volunteers could be distinguished from one another in a statistically significant manner (p < 0.001).</p> <p>Conclusion</p> <p>The questionnaire fulfilled the classical test quality criteria. With the LQPT there is an opportunity to test the theory underlying the CBASP model.</p
Stress System Dynamics during âLife As It Is Livedâ: An Integrative Single-Case Study on a Healthy Woman
Little is known about the dynamic characteristics of stress system activity during âlife as it is livedâ. Using as representative a study design as possible, this investigation sought to gain insights into this area. A healthy 25-year-old woman collected her entire urine over a period of 63 days in 12-h intervals (126 measurements) to determine cortisol and neopterin (immune activation marker) levels. In addition, she filled out questionnaires on emotional state and daily routine in 12-h intervals, and was interviewed weekly to identify emotionally negative and positive everyday incidents. Adjusted cross-correlational analyses revealed that stressful incidents were associated with cyclic response patterns in both urinary cortisol and urinary neopterin concentrations. Urinary cortisol levels first decreased 12â24 h after stressful incidents occurred (lag 1: â.178; pâ=â0.048) and then increased a total of 72â84 h later (lag 6: +.224; pâ=â0.013). Urinary neopterin levels first increased 0â12 h before the occurrence of stressful incidents (âlag 1: +.185; pâ=â0.040) and then decreased a total of 48â60 h following such stressors (lag 4: â.181; pâ=â0.044). Decreases in urinary neopterin levels were also found 24â36 and 48â60 h after increases in pensiveness (lag 2: â.215; pâ=â0.017) and depressiveness (lag 4: â.221; pâ=â0.014), respectively. Findings on emotionally positive incidents sharply contrasted with those dealing with negative experiences. Positive incidents were followed first by urinary cortisol concentration increases within 12 h (lag 0: +.290; pâ=â0.001) and then by decreases after a total of 60â72 h (lag 5: â.186; pâ=â0.039). Urinary neopterin levels first decreased 12â24 h before positive incidents occurred (âlag 2: â.233; pâ=â0.010) and then increased a total of 12â24 h following these incidents (lag 1: +.222; pâ=â0.014). As with previous investigations on patients with systemic lupus erythematosus (SLE), this study showed that stress system response can be considerably longer and more complex and differentiated than findings from conventional group studies have suggested. Further integrative single-case studies will need to be conducted in order to draw firm conclusions about stress system dynamics under real-life conditions
A bio-psycho-social exercise program (RĂCKGEWINN) for chronic low back pain in rehabilitation aftercare - Study protocol for a randomised controlled trial
<p>Abstract</p> <p>Background</p> <p>There is strong, internationally confirmed evidence for the short-term effectiveness of multimodal interdisciplinary specific treatment programs for chronic back pain. However, the verification of long-term sustainability of achieved effects is missing so far. For long-term improvement of pain and functional ability high intervention intensity or high volume seems to be necessary (> 100 therapy hours). Especially in chronic back pain rehabilitation, purposefully refined aftercare treatments offer the possibility to intensify positive effects or to increase their sustainability. However, quality assured goal-conscious specific aftercare programs for the rehabilitation of chronic back pain are absent.</p> <p>Methods/Design</p> <p>This study aims to examine the efficacy of a specially developed bio-psycho-social chronic back pain specific aftercare intervention (RĂCKGEWINN) in comparison to the current usual aftercare (IRENA) and a control group that is given an educational booklet addressing pain-conditioned functional ability and back pain episodes. Overall rehabilitation effects as well as predictors for compliance to the aftercare programs are analysed. Therefore, a multicenter prospective 3-armed randomised controlled trial is conducted. 456 participants will be consecutively enrolled in inpatient and outpatient rehabilitation and assigned to either one of the three study arms. Outcomes are measured before and after rehabilitation. Aftercare programs are assessed at ten month follow up after dismissal form rehabilitation.</p> <p>Discussion</p> <p>Special methodological and logistic challenges are to be mastered in this trial, which accrue from the interconnection of aftercare interventions to their residential district and the fact that the proportion of patients who take part in aftercare programs is low. The usability of the aftercare program is based on the transference into the routine care and is also reinforced by developed manuals with structured contents, media and material for organisation assistance as well as training manuals for therapists in the aftercare.</p> <p>Trial Registration</p> <p>Trial Registration number: NCT01070849</p
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