Reduction In Reserve Capacity Research Articles

Inertia Support Capability Evaluation for Wind Turbine Generators Based on Symmetrical Operation

With the increasing integration of new energy into the grid, the level of system inertia has been significantly reduced, posing a severe challenge to frequency stability. Consequently, there is an urgent need for wind turbine generators (WTGs) to actively provide inertia support through virtual inertia control. Assessing the inertia support capability of WTGs reasonably and setting appropriate controller parameters based on this assessment is a topic worthy of discussion. As WTGs’ characteristics are mostly ignored in the evaluation of inertia support capability for WTGs, an evaluation method based on symmetrical operation is proposed. The proposed method considers the impact of real inertia and aerodynamic characteristics, thereby helping to determine reasonable virtual inertia coefficients and de-loading reserve capacity for WTGs. With the proposed method, it can be determined that large WTGs can provide inertia support capabilities close to those of synchronous generators to the grid without exceeding a 0.1% reduction in reserve capacity during de-loading operation.

Mitochondrial toxicants in Xian-Ling-Gu-Bao induce liver injury by regulating the PI3K/mTOR signaling pathway: an in vitro study

BackgroundDrug-induced mitochondrial toxicity is thought to be a common mechanism of drug hepatotoxicity. Xian-Ling-Gu-Bao (XLGB) oral preparation is a commonly used drug for osteoporosis in China. Classical safety evaluation studies have shown that the entire preparation and six Chinese herbal medicines have high safety, but the incidence of drug-induced liver damage due to XLGB remains high, the mechanism and toxic substances causing liver injury are still unclear. The purpose of this study is to identify compounds with potential mitochondrial liabilities in XLGB, and to clarify their underlying mechanisms and related pathways.MethodsThe mitochondrial function analysis was performed using an extracellular flux assay, which simultaneously monitored both oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Through network pharmacology and in vitro experimental verification, the potential protein targets, signaling pathways and molecular mechanism of mitochondrial toxicity have been studied.ResultsWe observed a significant decrease in mitochondrial respiration of Psoraleae Fructus and its five compounds in fundamental bioenergetics parameters such as basal respiration, ATP-linked production and maximal respiration, indicating mitochondrial dysfunction. The network pharmacology results showed that the influence of XLGB on mitochondrial dysfunction was closely related to PI3K-Akt signaling pathway, mTOR signaling pathway and Apoptosis. Western blot showed that the levels of mTOR, p-mTOR (Ser2448), Raptor, PI3K (p110α), Beclin 1, ATG5 and Caspase-9 were up-regulated after treatment with psoralidin, psoralen and bavachin, and the expression of Bcl-2 was down-regulated after bavachinin treatment.ConclusionsThe hepatotoxicity of XLGB is associated with mitochondrial dysfunction. Five compounds in Psoraleae Fructus showed mitochondrial damage, they are psoralidin, isobavachalcone, bavachinin, bavachin and psoralen, especially psoralidin showed significant reduction in reserve capacity and respiratory control ratios. The molecular mechanism is related to the activation of PI3K/mTOR signaling pathway to inhibit autophagy and induce mitochondrial apoptosis.

FRAILTY IN REACH II CAREGIVERS: A SECONDARY DATA ANALYSIS

Frailty, a reduction in reserve capacity in people who are otherwise considered healthy, affects between 9 and 13% of adults who are older. Frailty is a poorly understood syndrome; however, frailty is correlated with negative CV procedure outcomes, falls and institutionalization. Little is known about frailty in caregivers. A secondary data analysis was conducted using the REACH II publicly available dataset and the Groningen Frailty Index (GFI). At consent two percent of REACH II caregivers had difficulty going to the toilet while 11% had difficulty walking outdoors. More than 1/3 had hearing and vision losses. 75% felt sad or dejected. 82% were taking more than 4 medications. Based on their calculated GFI, between 61% and 64% of the REACH II caregivers were frail. Frail caregivers and their care recipient were less likely to go to the emergency department (-0.110 coefficient; p = 0.004 95% CI -0.184 -0.035) and were less likely to be hospitalized overnight during the past 6 months (-0.121 coefficient; p=0.004; 95% CI -0.203 -0.040). Frailty is an under-recognized syndrome in caregivers. Little is known about the impact of frailty on the caregiving dyad; however, ED utilization and hospitalization was decreased in these caregivers and their care recipients. This decrease may imply a delay in seeking care; and, in fact, lead to worse health outcomes for the dyad. With the aging of Baby Boomers and the continued dependence for long term care delivered by unpaid caregivers, implementation of programs to prevent and treat frailty in caregivers is essential.

Population-based structural identification for reserve-capacity assessment of existing bridges

Transportation networks provide an essential contribution to addressing the needs of reliable and safe mobility in urban environments. The core of these networks is made up of infrastructure such as roads and bridges that often, have not been designed to meet current needs. Optimal management requires an accurate knowledge of how existing structures behave. This helps avoid unnecessary replacement and expensive interventions when cheaper and more sustainable alternatives are available. Structural-model updating takes advantage of measurements and more qualitative observations to identify suitable behaviour model classes and values for parameters that influence real behaviour. Error domain model falsification (EDMF) has been proposed as a robust population-based methodology to identify sets of models by comparing finite-element model predictions with measurements at sensor locations. This paper introduces a methodology, which is compatible with EDMF, to assess the reserve capacity of bridges for serviceability and ultimate limit states. A case study—the structural identification of a reinforced-concrete bridge in Singapore—illustrates the framework developed for the estimation of reserve capacity. Several analyses with increasing levels of model detail using design and updated values of relevant parameters are presented. Traffic-load specifications of design-stage codes (British Code—1978) and current codes (Eurocodes) are compared. Results show that typical conservative practices carried out during design and construction have led to an as-built reserve capacity of 60%. A large proportion of the as-built reserve capacity has been exploited to accommodate dramatically increased values of traffic-load specifications that are provided by current Singapore codes which have caused a reduction in reserve capacity to 20%. Such a reduction may be less significant in countries where code specifications have not changed as much. Finally, it is shown that advanced methods of analysis and assessment are more suitable than design-stage approaches to quantify the reserve capacity.

Rearrangement of Neuroendocrine Systems in the Mountains

The aim of this research was to study the functional state of the anterior pituitary, thyroid, adrenal, and reproductive glands and their relationship with chronic exposure to high altitude. Studies were conducted in high altitudes inhabitants of the Tien-Shan (1200 m, 2800 m, 3600 m). Adrenocorticotropic hormone (ACTH), cortisol, catecholamines, thyroid, and sex hormones were determined by immunosorbent and spectrofluorometric methods. Normal hormone levels for sea level inhabitants were used for comparison. Increased cortisol levels in mountaineers (M) (2800 m) may reflect a reduction in reserve capacity of the pituitary-adrenocortical system and the formation of their chronic condition or incomplete adaptation, or the continuing adaptation to the environment in a number of successive generations. Reduced activity of the pituitary-adrenocortical system in high altitude residents (HAR) at 3600 m is a consequence of the harsh weather conditions, narrowing the boundaries of the organism’s adaptation and facilitating economical and appropriate regulation. High altitude residents at 2800 m and 3600 m (when compared to the normal hormone levels and data of low mountain residents at 1200 m), presented a predominance of the mediator activity of the hormone sympathetic-adrenal system, showing an increased secretion of norepinephrine and dopamine, and a decreased secretion of epinephrine. Increased levels of norepinephrine are associated with its decreased metabolism and reserves, providing constant catecholamines that create the preconditions for a stable and long-term work of the body, providing an adequate state of physiological function. Features power (prevalence of carbohydrates and fats in food M and HAR) also lead to the activation secretion of norepinephrine, which leads to intensive use of the biological mediator precursor, dopamine, as evidenced by its high level in residents at both altitudes. This change in optimum reserve of catecholamines promotes an accelerated restoration of catecholamine levels. Prolonged exposure to high altitude hypoxia induces contrasting changes in thyroid hormone levels. The mountaineers (2800 m) are found close to the low values of normal TSH levels, whereas thyroid hormones tend to increase. The increase in T3 and T4 levels, while maintaining the basic concentration of TSH or small hyperthyroidism, seem necessary to adapt to the extreme conditions of high mountains. Increased levels of T4, TSH and norepinephrine, with a decreased secretion of T3 in HAR (3600 m), reflect an additional reaction on the PTS factor constant exposure to cold in the mountains. Low values ​​of T3 without changes in TSH and T4 levels are explained by the influence of cold. The detected levels of testosterone in male HAR (3600 m) show the adverse effects of environmental factors, and reduced levels of progesterone (89%) indicate a hard endocrine function of women M (2800 m), on the mobilization of the strategic reserve endocrine system. However, the decreased functional activity of the sex glands does not exceed the boundaries of conventional indicators, which are a reflection of the body’s resistance. Conclusion: Features of endocrine systems in high-population of Tien-Shan include reduced activity of the pituitary-adrenocortical system in the organism, and economical operation, which allows for normal life, work and heavy physical activities in the specific conditions of the mountains. The parameters of endocrine status should be assessed only in relation to its their own mountain normal population values.

New directions in the diagnosis and treatment of endometritis

Objective: to develop a comprehensive diagnosis and evaluation of the clinical efficacy of pathogenetic therapy of acute and chronic endometritis. Methods: patients under went complex clinical and instrumental and immunological assessment of the interferon, immune status and cytokines in the serum and in the aspirate of the endometrium before and after complex therapy. Results: in acute endometritis in the endometrium aspirate marked by high levels of proinflammatory cytokines with a predominance of IL1β and IL6, indicating the severity and predicts the outcome of the disease. The levels of proinflammatory cytokines in the aspirate from the uterine cavity increased 5-8 times compared with the serum (in 3–5 times), which confirms the more pronounced local inflammatory response, and supports local immunocorrection. In chronic endometritis showed a reduction in reserve capacity of the immune cells in the induction of leukocytes in vitro. Conclusions: Confirmed the need for correction of all parts of the immune system. To determine the spread of the inflammatory process and choice of tactics of local immunotherapy in acute endometritis on the background of spontaneous abortion or non-developing pregnancy, removal of fragments of chorionic or placental tissue effectively under the control of hysteroscopy, assessment of cytokine production (IL-1β, TNF-α, IL-6, IL-8, IL-1RA, IL-4, IL-10) in the endometrium and morphological diagnosis. Tactics immunorehabilitation using a preparation of recombinant interferon-α2b in patients with endometritis.

Novel method to assess arterial insufficiency in rodent hind limb

BackgroundLack of techniques to assess maximal blood flow capacity thwarts the use of rodent models of arterial insufficiency to evaluate therapies for intermittent claudication. We evaluated femoral vein outflow (VO) in combination with stimulated muscle contraction as a potential method to assess functional hind limb arterial reserve and therapeutic efficacy in a rodent model of subcritical limb ischemia. Materials and methodsVO was measured with perivascular flow probes at rest and during stimulated calf muscle contraction in young, healthy rats (Wistar Kyoto, WKY; lean Zucker rats, LZR) and rats with cardiovascular risk factors (spontaneously hypertensive [SHR]; obese Zucker rats [OZR]) with acute and/or chronic femoral arterial occlusion. Therapeutic efficacy was assessed by administration of Ramipril or Losartan to SHR after femoral artery excision. ResultsVO measurement in WKY demonstrated the utility of this method to assess hind limb perfusion at rest and during calf muscle contraction. Although application to diseased models (OZR and SHR) demonstrated normal resting perfusion compared with contralateral limbs, a significant reduction in reserve capacity was uncovered with muscle stimulation. Administration of Ramipril and Losartan demonstrated significant improvement in functional arterial reserve. ConclusionsThe results demonstrate that this novel method to assess distal limb perfusion in small rodents with subcritical limb ischemia is sufficient to unmask perfusion deficits not apparent at rest, detect impaired compensation in diseased animal models with risk factors, and assess therapeutic efficacy. The approach provides a significant advance in methods to investigate potential mechanisms and novel therapies for subcritical limb ischemia in preclinical rodent models.

Endothelial dysfunction indicators in patients with diabetic foot syndrome

In recent years, scientists have become increasingly interested in the role of the endothelium in the pathogenesis of vascular lesions of various origins, including diabetic patients. Therefore, the aim of the study was to investigate the expression of endothelial dysfunction in patients with diabetic foot syndrome (DFS), by examining the levels of nitric oxide, endothelin-1 levels in the serum, as well as lower limb microcirculation by laser doppler flowmetry. It was examined 72 patients with diabetic foot syndrome with I-IV degree of lesion (by Meggit- Wagner classification). Neuropathic form was diagnosed in 32 people, ischemic--40 patients. The function of endothelium was studied on the basis of the determination of enzyme-linked immunosorbent NO and endothelin-1 in peripheral blood serum, as well as to assess the state of the microcirculation of the lower limbs by laser doppler flowmetry, using apparatus LACK-02 (Russia). Patients with DFS are marked with endothelial dysfunction, the severity of which depends on the type of diabetes, glycemic level and pathogenic forms of destruction. This is manifested by secretion reducing of vasodilators (NO) and increased synthesis of vasoconstrictors (endothelin-1), which leads to disruption of peripheral hemodynamic. Characteristic changes in the microcirculation are a dramatic violation of endothelium-dependent regulation mechanism, the redistribution of blood towards the nutritional circulation. Also it is showed a significant reduction in reserve capacity of the capillary bed in response to the sample and the occlusal restoration of blood flow during reactive hyperemia. Development of endothelial dysfunction and changes in peripheral hemodynamic in patients with DFS contributes to the emergence and prolongation of necrotic lesions, as well as violation of reparative processes.

Geriatric Assessment to Improve Risk Stratification in Older Patients Undergoing Coronary Revascularization

Within the next 20 years, nearly one quarter of the population will be aged ≥65 years.1 Cardiovascular morbidity and mortality rise rapidly after age 65, and this group accounts for 60% of myocardial infarction-related deaths.2 The high burden of comorbid conditions and concomitant lower physiological reserve render this group more complex and fundamentally different from its younger counterparts. Article see p 496 The concept of frailty has gained general acceptance in geriatric medicine as an important prognostic indicator for a range of adverse outcomes. According to current views, frailty can be defined as a physiological state of increased vulnerability to stressors that results from decreased physiological reserves. This reduction in reserve capacity results in difficulty maintaining homeostasis in the face of perturbations, including injury, acute illness, and invasive procedures.3 Although a consensus definition and corresponding assessment tool do not exist yet,4 a widely used operational phenotype for frailty includes 5 criteria: exhaustion, weight loss, low physical activity, weak hand grip, and slow gait speed.5 There is emerging interest in understanding the role of frailty as it pertains to acute coronary care in elderly persons. A previous systematic review found that the prevalence of frailty was >50% among patients with severe coronary artery disease or heart failure and that …

Aging of the human neuromuscular system.

Loss of cells from the motor system occurs during the normal aging process, leading to reduction in the complement of motor neurons and muscle fibers. The latter age-related decrease in muscle mass has been termed "sarcopenia" and is often combined with the detrimental effects of a sedentary lifestyle in older adults, leading to a significant reduction in reserve capacity of the neuromuscular system, which is the primary subject of this review. Clear evidence of this aging effect is seen when voluntary or stimulated muscle strength is compared across the adult lifespan, with a steady decline of approximately 1-2% per year occurring after the sixth decade. Interestingly, when compared with isometric contractions, the effect of aging is more pronounced for concentric movements and less for eccentric movements (i.e., muscle shortening versus lengthening). This phenomenon appears to be linked to the stiffer muscle structures and prolonged myosin crossbridge cycles of aged muscles. It is encouraging that the capability of physiological adaptations in the motor pathways remains into very old age--when an appropriate exercise stimulus is given--and long-term prevention strategies are advocated to avoid excessive physical impairments and activity restrictions in this age group.

Functional and metabolic consequences of sarcopenia.

Sarcopenia associated with the normal aging process is often combined with the detrimental effects of a sedentary lifestyle in older adults, leading to a significant reduction in reserve capacity of the neuromuscular system. A clear example of the aging effect is the pattern of reduction in muscle strength after the sixth decade for both isometric and concentric contractions. However, older adults are relatively stronger for movements in which muscles lengthen, due to the inherent advantage of eccentric contractions, plus their stiffer muscle structures and prolonged myosin cross-bridge cycles. Also, the capacity for physiological adaptations in the motor pathways remains into very old age when an appropriate exercise stimulus is given, and older adults can obtain adaptations in both enhanced neural control of motor units and increased protein synthesis leading to moderate muscle hypertrophy. Since periods of sedentary lifestyle or bed rest due to illness can have severe detraining consequences on the neuromuscular function of an older person, long-term prevention strategies are advocated to avoid excessive physical impairments and activity restrictions in this age group.

Post-carotid endarterectomy hyperperfusion syndrome: Preliminary observations for identifying at risk patients by transcranial doppler sonography and the acetazolamide test

Patients at risk of hyperperfusion syndrome after carotid endarterectomy are often severely hypertensive and have a high grade internal carotid artery stenosis with disordered autoregulation due to a loss of reserve capacity (RC). Cerebral RC can be studied by sophisticated and expensive technical devices (SPECT, PET). Recently it has been demonstrated that the transcranial Doppler (TCD) and acetazolamide provocation test can be used to assess RC. From September 1991 to January 1992, 36 patients were studied by the TCD and acetazolamide test prior to carotid endarterectomy to identify patients at high risk of the hyperperfusion syndrome. Preoperatively, the patients were studied by TCD at rest and after vasolidation with acetazolamide 1 g intravenously (i.v.). Mean blood flow velocity on the middle cerebral artery (MCAv) was recorded for the following 20 min at 5 min intervals. MCAv at rest was 49 +/- 17 cm/s. After acetzaolamide infusion in 33 patients (92%), the mean MCAv was 62 +/- 19 cm/s with an increase of 19 +/- 13 cm/s (normal RC). In three patients (8%), the mean MCAv was 43 +/- 22 cm/s with a decrease of -6 +/- 3 cm/s with respect to base values (reduction of RC). (t = 3.30; p = 0.0022). All these patients were hypertensive (BP > 180/100 mmHg) and had a carotid artery stenosis > 90%. Postoperatively, the three patients with reduction of RC complained of homolateral headache. TCD showed a mean MCAv of 67 +/- 17 cm/s, an increase compared to the preoperative rest values of 17 +/- 8 cm/s, the 33 patients with normal RC showed a mean change in MCAv -2 +/- 12 cm/s.(ABSTRACT TRUNCATED AT 250 WORDS)