Periods Of High Stress Research Articles

Stress Emotion Recognition Based on RSP and EMG Signals

To recognize the stress emotion, a subject was put alternately in periods of high and low stress by configuring the speed and difficulty of a game named Tetris. The respiration (RSP) signal and the electromyogram (EMG) signal with different stress level were then acquired. After preprocessing, the mathematical features were calculated and automatic detection of stress level based on Fisher linear discriminant classifier was realized. The results show that the average correct detection rate of stress level based on the EMG signal can reach 97.8%. That of the RSP signal is only 86.7%. The EMG signal is more effective than the RSP signal in detection of stress level. Union of multiple physiological signals can effectively improve the correct detection rate.

Age-Related Changes in Mitochondrial Membrane Composition of Nothobranchius rachovii

Mitochondrial membrane composition may be a critical factor in the mechanisms of the aging process by influencing the propagation of reactions involved in mitochondrial function during periods of high stress. Changes affecting either lipid class or fatty acid compositions could affect phospholipid properties and alter mitochondrial function and cell viability. In the present study, mitochondrial membrane phospholipid compositions were analyzed throughout the life cycle of Nothobranchius rachovii. Mitochondrial phospholipids showed several changes with age. Proportions of cardiolipin decreased and those of sphingomyelin increased between 11- and 14-month-old fish. Fatty acid compositions of individual phospholipids in mitochondria were also significantly affected with age. These data suggest increasing damage to mitochondrial lipids during the life cycle of N. rachovii that could be one of the main factors related with and contributing to degraded mitochondrial function associated with the aging process.

The real consequences of financial stress

We introduce a dynamic banking-macro model, which abstains from conventional mean-reversion assumptions and in which—similar to Brunnermeier and Sannikov (2010)—adverse asset-price movements and their impact on risk premia and credit spreads can induce instabilities in the banking sector. To assess such phenomena empirically, we employ a multi-regime vector autoregression (MRVAR) approach rather than conventional linear vector autoregressions. We conduct bivariate empirical analyses, using country-specific financial-stress indices and industrial production, for the U.S., the UK and the four large euro-area countries. Our MRVAR-based impulse-response studies demonstrate that, compared to a linear specification, response profiles are dependent on the current state of the economy as well as the sign and size of shocks. Previous multi-regime-based studies, focusing solely on the regime-dependence of responses, conclude that, during a high-stress period, stress-increasing shocks have more dramatic consequences for economic activity than during low stress. Conducting size-dependent response analysis, we find that this holds only for small shocks and reverses when shocks become sufficiently large to induce immediate regime switches. Our findings also suggest that, in states of high financial stress, large negative shocks to financial-stress have sizeable positive effects on real activity and support the idea of “unconventional” monetary policy measures in cases of extreme financial stress.

Potential trends in Attention Deficit Hyperactivity Disorder (ADHD) drug use on a college campus: Wastewater analysis of amphetamine and ritalinic acid

Attention Deficit Hyperactivity Disorder (ADHD) medication use is on the rise in the United States. The most widely used ADHD medications are the amphetamine-type compounds Adderall (mixed amphetamine salts) and Ritalin (methylphenidate). According to survey data ADHD medications are used as a study drug or “Smart Drug” by students without a prescription on college campuses. Survey data of non-prescribed drug use has limitations with accurate reporting and no empirical data of usage exists in the literature. This study looks for trends in the use of these drugs on a college campus among low-stress and high stress periods. The metabolites of these two drugs, amphetamine and ritalinic acid, are quantified in campus wastewater using solid phase extraction (SPE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS). Trends show a possible increase in amphetamine levels during periods of high stress such as midterms, the last week of classes and finals week over levels from the baseline low stress weeks such as the first week of classes. Both semesters from the 2011–12 academic year were studied and the highest increase over baseline (760%) occurred during finals week of the second semester. Ritalinic acid levels gradually climbed first semester but had no obvious periodic trend second semester.

Crosstalk between interleukin-6 and corticotropin-releasing factor modulate submucosal plexus activity and colonic secretion

Irritable bowel syndrome (IBS) is a common disorder of the gut with symptoms such as diarrhoea, constipation, abdominal pain and bloating, that are frequently exacerbated by stress. Circulating levels of the pro-inflammatory cytokine, interleukin-6 (IL-6), which can activate colonic enteric neurons, are elevated in IBS patients. These studies aim to explore the relationship between IL-6 and the stress peptide, corticotropin-releasing factor (CRF) in colonic submucosal neurons. Calcium imaging, Ussing chamber electrophysiology and immunohistochemistry were conducted on rat distal colons to investigate potential crosstalk between IL-6 and CRF. Colonic secretions from the maternal separation rat model of IBS stimulated increases in intracellular calcium in naïve submucosal neurons via CRF1 receptors (n=15, p<0.05). Moreover, IL-6 (n=50, p<0.01) but not IL-1β (n=46, p>0.05) or TNFα (n=46, p>0.05) potentiated the CRF-evoked calcium response. CRF (1μM, 1h, n=5) stimulation also induced colonic secretion of IL-6 and inhibited the pro-secretory effects of IL-6 on colonic ion transfer (n=12). These studies demonstrate the modulatory effects of CRF on colonic IL-6 secretion, neuronal activation and secretory function. These findings may provide an insight into the molecular mechanisms underlying symptom flares in IBS during periods of high stress.

Effects of US Monetary Policy Shocks During Financial Crises - A Threshold Vector Autoregression Approach

This paper analyzes the impact and effectiveness of conventional monetary policy during periods of low and high financial stress in the US economy. Using data from 1973Q1 to 2008Q4, the analysis is conducted by estimating a Threshold Vector Autoregression (TVAR) model to capture switching between the low and high financial stress regimes implied by the theoretical literature. The empirical findings support regime-dependent effects of conventional US monetary policy. In particular, the output response to monetary policy shocks is larger during periods of high financial stress than in periods of low financial stress. The existence of a cost channel effect during periods of high financial stress imply a worsening of the short run output-inflation trade off during financial crises. When the sample period is extended to 2012Q4, there is evidence that expansionary monetary policy continues to be effective during periods of high financial stress when the prevailing interest rate is at the zero lower bound. By keeping interest rates and credit spreads low, expansionary monetary policy helps shift the US economy from high to low financial stress regimes. Large expansionary monetary policy shocks also increase the likelihood of moving the economy out of a high financial stress regime.

Application of Satellite Products to Study Upwelling, Chlorophyll and Mixed Layer Depth of Southeastern Arabian Sea

The role of wind stress in modulating upwelling and subsequent changes in mixed layer depth and chlorophyll concentration in southeastern Arabian Sea are studied for the period encompassing 2000–2008. During southwest monsoon season favoring upwelling in this region, it is observed that decrease in wind stress is always followed by an increase in chlorophyll concentration with approximately two weeks delay, accompanied by the shoaling of mixed layer depth, whereas the opposite is observed during high wind stress periods. This is attributed to the mixing and entrainment of nutrients into the euphotic zone which enable increase in surface chlorophyll and thereby boosting the primary productivity of the region. Wavelet analysis is used to deduce the temporal variability of winds, chlorophyll and mixed layer for the region. A time lag of 2 weeks is observed between the decrease in wind stress followed by a high in the surface chlorophyll concentration, often well captured by satellite. Another interesting observation is the bimodal variability of chlorophyll-a concentration during summer monsoon is observed in this region which was hitherto unnoticed. This spatial and temporal relation between wind, chlorophyll and mixed layer depth can provide valuable insight towards future studies on upwelling induced productivity for this region.

Advances in the Wilshire extrapolation technique—Full creep curve representation for the aerospace alloy Titanium 834

Abstract Structural alloys applied to aerospace and power generation applications are expected to operate at temperatures exceeding those originally envisaged during their design to meet the tightening regulations on emissions and also to improve the efficiency of operation. Extended periods of high stress over time will induce creep deformation and, eventually, static failures in such alloys. For this reason, prior to using these alloys in such applications, their deformation behaviour has to be studied through mechanical testing. However, testing might vary from few hours up to several months which, in return, will have a considerable influence on the cost of these components. As an alternative, a new extrapolation technique, ‘The Wilshire Equations’, has been developed at Swansea University in order to predict the creep rupture behaviour. In addition, this technique has been extended to re-construct full creep curves based on short-term measurements. This new capability will, thus, reduce the cost and the time required to carry out such long-term tests. As a model material, Titanium 834, which is currently used in aeroengine applications, has been employed for the analysis using the Wilshire approach.

Provision of pandemic disease information by health sciences librarians: a multisite comparative case series

The research provides an understanding of pandemic information needs and informs professional development initiatives for librarians in disaster medicine. Utilizing a multisite, comparative case series design, the researchers conducted semi-structured interviews and examined supplementary materials in the form of organizational documents, correspondence, and websites to create a complete picture of each case. The rigor of the case series was ensured through data and investigator triangulation. Interview transcripts were coded using NVivo to identify common themes and points of comparison. Comparison of the four cases revealed a distinct difference between "client-initiated" and "librarian-initiated" provision of pandemic information. Librarian-initiated projects utilized social software to "push" information, whereas client-initiated projects operated within patron-determined parameters to deliver information. Health care administrators were identified as a key audience for pandemic information, and news agencies were utilized as essential information sources. Librarians' skills at evaluating available information proved crucial for selecting best-quality evidence to support administrative decision making. Qualitative analysis resulted in increased understanding of pandemic information needs and identified best practices for disseminating information during periods of high organizational stress caused by an influx of new cases of an unknown infectious disease.

Nichtdermatomgebundene somatosensorische Defizite bei chronischen Schmerzpatienten

Nondermatomal somatosensory deficits (NDSDs) are frequently found in chronic pain patients and allude to pain sensitization and pain centralization. In the clinical examination NDSDs are as a rule accompanied by hyposensitivity to touch and heat perception often with a quadrantal or hemibody distribution. The majority of NDSD patients show a trigger episode with a somatic nociceptive trauma in the case history. These somatic findings, however, never fully explain the pain disorder, analogue to the complex regional pain syndrome (CRPS). Most patients with chronic pain disorders as well as those with NDSD often report an antecedent period of high psychobiological stress. The data from functional imaging reveal a complex pattern of a central nervous dysregulation.

Is Real Estate a Good Way to Diversify in Times of Financial Crisis?

This paper investigates the diversification benefits of indirect real estate investments in market downturns. We model the dependence structure between REITs and traditional assets by using a mixed-copula framework within a regime switching model. The Clayton copula dominates in the mixture. We showed that correlations increase during periods of high volatility and market stress. Indirect real estate investments do not provide an adequate level of downside protection and tend to increase the portfolio risk during times of crisis.

CONCENTRATIONS OF DIMETHYLSULFONIOPROPIONATE AND DIMETHYL SULFIDE ARE STRAIN-SPECIFIC IN SYMBIOTIC DINOFLAGELLATES (SYMBIODINIUM SP., DINOPHYCEAE)(1).

Dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) are sulfur compounds that may function as antioxidants in algae. Symbiotic dinoflagellates of the genus Symbiodinium show strain-specific differences in their susceptibility to temperature-induced oxidative stress and have been shown to contain high concentrations of DMSP. We investigated continuous cultures of four strains from distinct phylotypes (A1, A13, A2, and B1) that can be characterized by differential thermal tolerances. We hypothesized that strains with high thermal tolerance have higher concentrations of DMSP and DMS in comparison to strains with low thermal tolerance. DMSP concentrations were strain-specific with highest concentrations occurring in A1 (225 ± 3.5 mmol · L(-1 ) cell volume [CV]) and lowest in A2 (158 ± 3.8 mmol · L(-1 ) CV). Both strains have high thermal tolerance. Strains with low thermal tolerance (A13 and B1) showed DMSP concentrations in between these extremes (194 ± 19.0 and 160 ± 6.1 mmol · L(-1 ) CV, respectively). DMS data further confirmed this general pattern with high DMS concentrations in A1 and A13 (4.1 ± 1.22 and 2.1 ± 0.37 mmol · L(-1 ) CV, respectively) and low DMS concentrations in A2 and B1 (0.3 ± 0.06 and 0.5 ± 0.22 mmol · L(-1) CV, respectively). Hence, the strain-specific differences in DMSP and DMS concentrations did not match the different abilities of the four phylotypes to withstand thermal stress. Future work should quantify the possible dynamics in DMSP and DMS concentrations during periods of high oxidative stress in Symbiodinium sp. and address the role of these antioxidants in zooxanthellate cnidarians.

A Mixed-Method Approach to Understanding the Experiences of Non-Deployed Military Caregivers

Given the unprecedented operational tempo of the Afghanistan and Iraq wars and the heavy involvement of the Reserve and National Guard, the stress that military families are exposed to is distinct from stress in earlier conflicts, with little empirical data to inform the impact on non-deployed military caregivers or "home caregivers." The study seeks to examine the experiences of home caregivers during deployments, with a focus on the impact of deployment on the caregiver's well-being. We conducted 50 qualitative interviews and 1,337 survey interviews with home caregivers who experienced at least one deployment. The structured qualitative interview focused on caregiver experiences during deployment. The quantitative data centered on caregiver well-being and household and relationship hassles. The qualitative interview notes were the unit of analysis and traditional methods were used to analyze the data. The quantitative data were analyzed using regression models. The qualitative data revealed key deployment-related household challenges that caregivers experience and the effect of those challenges on caregivers. Multivariate analyses of the quantitative data explored differences in caregivers' emotional well-being, household and relationship hassles. The results showed important component and deployment experience differences. Caregivers affiliated with the National Guard and those with more months of deployment reported significantly poorer emotional well-being, and more household and relationship hassles. Given the important role that maternal well-being has on child and family functioning, it is critical to understand how the stress of deployment is affecting mothers in their daily routines, especially during potentially high stress periods.

Design and Demonstration of a Microbiaxial Optomechanical Device for Multiscale Characterization of Soft Biological Tissues with Two-Photon Microscopy

The biomechanical response of tissues serves as a valuable marker in the prediction of disease and in understanding the related behavior of the body under various disease and age states. Alterations in the macroscopic biomechanical response of diseased tissues are well documented; however, a thorough understanding of the microstructural events that lead to these changes is poorly understood. In this article we introduce a novel microbiaxial optomechanical device that allows two-photon imaging techniques to be coupled with macromechanical stimulation in hydrated planar tissue specimens. This allows that the mechanical response of the microstructure can be quantified and related to the macroscopic response of the same tissue sample. This occurs without the need to fix tissue in strain states that could introduce a change in the microstructural configuration. We demonstrate the passive realignment of fibrous proteins under various types of loading, which demonstrates the ability of tissue microstructure to reinforce itself in periods of high stress. In addition, the collagen and elastin response of tissue during viscoelastic behavior is reported showing interstitial fluid movement and fiber realignment potentially responsible for the temporal behavior. We also demonstrate that nonhomogeneities in fiber strain exist over biaxial regions of assumed homogeneity.

Sympathetic nerve activity in normal and cystic follicles from isolated bovine ovary: local effect of beta-adrenergic stimulation on steroid secretion

Cystic ovarian disease (COD) is an important cause of abnormal estrous behavior and infertility in dairy cows. COD is mainly observed in high-yielding dairy cows during the first months post-partum, a period of high stress. We have previously reported that, in lower mammals, stress induces a cystic condition similar to the polycystic ovary syndrome in humans and that stress is a definitive component in the human pathology. To know if COD in cows is also associated with high sympathetic activity, we studied isolated small antral (5mm), preovulatory (10mm) and cystic follicles (25mm). Cystic follicles which present an area 600 fold greater compared with preovulatory follicles has only 10 times less concentration of NE as compared with small antral and preovulatory follicles but they had 10 times more NE in follicular fluid, suggesting a high efflux of neurotransmitter from the cyst wall. This suggestion was reinforced by the high basal release of recently taken-up 3H-NE found in cystic follicles. While lower levels of beta-adrenergic receptor were found in cystic follicles, there was a heightened response to the beta-adrenergic agonist isoproterenol and to hCG, as measured by testosterone secretion. There was however an unexpected capacity of the ovary in vitro to produce cortisol and to secrete it in response to hCG but not to isoproterenol. These data suggest that, during COD, the bovine ovary is under high sympathetic nerve activity that in addition to an increased response to hCG in cortisol secretion could participate in COD development.

Invasive species can handle higher leaf temperature under water stress than Mediterranean natives

Thermal tolerance of Photosystem II (PSII) highly influences plant distribution worldwide because it allows for photosynthesis during periods of high temperatures and water stress, which are common in most terrestrial ecosystems and particularly in dry and semi-arid ones. However, there is a lack of information about how this tolerance influences invasiveness of exotic species in ecosystems with seasonal drought. To address this question for Mediterranean-type ecosystems (MTE) of the Iberian Peninsula, we carried out an experiment with fifteen phylogenetically related species (8 invasive and 7 native, Pinus pinaster Ait., Pinus radiata D. Don, Schinus molle Linn., Elaeagnus angustifolia L., Eucalyptus globulus Labill., Acacia melanoxylon R. Br., Gleditsia triacanthos L., Pistacia terebinthus L., Rhamnus alaternus L., Anagyris foetida L., Colutea arborescens L., Oenothera biennis L., Epilobium hirsutum L., Achillea filipendulina Lam. and Achillea millefolium L). Seedlings were grown and maximal photochemical efficiency of PSII (Fv/Fm) was measured at two water availabilities (well-watered and with water stress). PSII thermal tolerance measurements were related to specific leaf area (SLA), which varied significantly across the study species, and to the mean potential evapotranspiration (PET) of the month with the lowest precipitation in the native areas of both groups and in the invaded area of the Iberian Peninsula. Additionally, PSII thermal tolerance measurements under water stress were phylogenetically explored. Invasive and native species neither differed in SLA nor in their thermal tolerance under well-watered conditions. For well-watered plants, SLA was significantly and positively related to PSII thermal tolerance when all species were explored together regardless of their invasive nature. However, this relationship did not persist under water stress and invasive species had higher plastic responses than Mediterranean natives resulting in higher leaf temperatures. Higher PSII thermal tolerance could explain invasiveness because it allows for longer periods of carbon acquisition under water stress. In fact, PSII thermal tolerance was positively related to the PET of the invaded and native areas of the Iberian Peninsula. PSII thermal tolerance was not related to PET at the native range of the invasive species, suggesting that successful invasive species were plastic enough to cope with novel dry conditions of the Iberian Peninsula. Moreover, our phylogenetic results indicate that future scenarios of increased aridity in MTE associated to climate change will filter invasion success by taxonomic identity. This study reveals the importance of studying ecophysiological traits to understand and better predict future biological invasions.

Using mirror visual feedback and virtual reality to treat fibromyalgia

Fibromyalgia is a condition characterized by long term body-wide pain and tender points in joints, muscles and soft tissues. Other symptoms include chronic fatigue, morning stiffness, and depression. It is well known that these symptoms are exacerbated under periods of high stress. When pain becomes severe enough, the mind can enter what is known as a dissociative state, characterized by depersonalization - the feeling of detachment from one's physical body and the illusion of watching one's physical body from outside. In evolutionary terms, dissociative states are thought to be an adaptive mechanism to mentally distance oneself from pain, often during trauma. Similar dissociative experiences are reported by subjects who have used psychoactive drugs such as ketamine. We have previously used non-invasive mirror visual feedback to treat subjects with chronic pain from phantom limbs and suggested its use for complex regional pain syndrome: once considered intractable pain. We wondered whether such methods would work to alleviate the chronic pain of fibromyalgia. We tested mirror visual feedback on one fibromyalgia patient. On 15 trials, the patient's lower limb pain rating (on a scale from 1 to 10) decreased significantly. These preliminary results suggest that non-invasive dissociative anesthetics such as VR goggles, ketamine, and mirror visual feedback could be used to alleviate chronic pain from fibromyalgia. This would furnish us with a better understanding of the mechanism by which external visual feedback interacts with the internal physical manifestation of pain.

Seasonal spawning and wind‐regulated retention‐dispersal of early life stage Atlantic cod (Gadus morhua) in a Newfoundland fjord

AbstractSequential ichthyoplankton surveys were used to determine the spatial and temporal distribution of eggs and larvae over coastal spawning grounds of Atlantic cod (Gadus morhua) in Smith Sound, Trinity Bay, Newfoundland, during the spring and summer of 2006 and 2007. Egg densities showed similar patterns for both years with two peaks in abundance in spring (March–April) and late summer (late July). A clear progression of development stages (1–4) was observed in spring and summer in 2006 and summer in 2007, suggesting retention of eggs within the Sound during these periods. Modelled predictions of vertical egg distributions indicated eggs were broadly distributed near the surface during spring (March–April), but were concentrated below the pycnocline (&gt;10 m) within the inner portions of the Sound during the summer months (July–August). Back‐calculated peaks in spawning based on water temperatures were estimated at 11 and 4 April for 2006 and 2007, respectfully, with late season peaks centred on 21–24 July for both years. Environmental data indicated cooler water temperatures and periods of high wind stress in spring, and warmer, calmer periods late summer, consistent with higher retention and faster development times on the spawning grounds later in the season. We conclude that spring and summer spawning events result in different distributions of early life stages and may lead to different distributions of juvenile and adult fish.

Modeling patterns of coral bleaching at a remote Central Pacific atoll

A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8–30.1°C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress.

Speeding through the Frat House: A Qualitative Exploration of Nonmedical Adhd Stimulant Use in Fraternities

Qualitative methods were used to investigate the use of nonmedical Attention Deficit Hyperactivity Disorder (ADHD) stimulants by fraternity members. The primary goal of the study was to determine students' levels of understanding and motivations for use of these Schedule II controlled substances. Seventy-nine in-depth interviews were conducted. Key findings highlighted how: a) easy it was for subjects to obtain stimulants; b) little health information nonmedical users have about stimulants; c) academic stress created a fertile context for stimulant use; and d) a small number of prescribed users supply the vast majority of nonmedical users with their stimulants. Most nonmedical users claimed to primarily use ADHD stimulants in periods of high academic stress and believed that they not only reduced fatigue, but also increased reading comprehension, interest, cognition, and memory. These qualitative data have supplied a rich and complex understanding behind nonmedical ADHD stimulant use among fraternity members.