Set Point For Regulation Research Articles

Normocalcemic hyperparathyroidism after successful parathyroidectomy for single parathyroid adenoma: Prevalence, etiological factors, predictive markers, treatment and evolution

Background and objectivePostparathyroidectomy normocalcemic hyperparathyroidism (PPNCHPPT) is a frequent situation for which we have no information in our country. The objective is to know our prevalence of PPNCHPPT, the associated etiological factors, the predictive markers, the treatment administered and the evolution. Patients and methodRetrospective observational cross-sectional study on 42 patients. Twelve patients with PPNCHPPT and 30 without PPNCHPPT are compared. ResultsHPPTNCPP prevalence: 28.6%. Etiological factors: vitamin D deficiency: 75%; bone remineralization: 16.7%; renal failure: 16.7%; hypercalciruria: 8.3%. No change in the set point of calcium-mediated parathormone (PTH) secretion was observed, but an increase in the preoperative PTH/albumin-corrected calcium (ACC) ratio was observed. Predictive markers: PTH/ACC ratio (AUC 0.947; sensitivity 100%, specificity 78.9%) and PTH (AUC 0.914; sensitivity 100%, specificity 73.7%) one week postparathyroidectomy. Evolution: follow-up 30 ± 16.3 months: 50% normalized PTH and 8.3% had recurrence of hyperparathyroidism. Patients with PPNCHPPT less frequently received preoperative treatment with bisphosphonates and postoperative treatment with calcium salts. ConclusionsThis is the first study in our country that demonstrates a mean prevalence of PPNCHPPT, mainly related to a vitamin D deficiency and a probable resistance to the action of PTH, which can be predicted by the PTH/ACC ratio and PTH a week post-intervention and often evolves normalizing the PTH. We disagree with the etiological effect of hypercalciuria and the change in the PTH/calcemia regulation set point, and we acknowledge the scant treatment administered with calcium salts in the postoperative period.

Hiperparatiroidismo normocalcémico tras paratiroidectomía exitosa por adenoma único paratiroideo: prevalencia, factores etiológicos, marcadores predictivos, tratamiento y evolución

Background and objectivePostparathyroidectomy normocalcemic hyperparathyroidism (PPNCHPPT) is a frequent situation for which we have no information in our country. The objective is to know our prevalence of PPNCHPPT, the associated etiological factors, the predictive markers, the treatment administered and the evolution. Patients and methodRetrospective observational cross-sectional study on 42 patients. Twelve patients with PPNCHPPT and 30 without PPNCHPPT are compared. ResultsHPPTNCPP prevalence: 28.6%. Etiological factors: vitamin D deficiency: 75%; bone remineralization: 16.7%; renal failure: 16.7%; hypercalciruria: 8.3%. No change in the set point of calcium-mediated parathormone (PTH) secretion was observed, but an increase in the preoperative PTH/albumin-corrected calcium (ACC) ratio was observed. Predictive markers: PTH/ACC ratio (AUC 0.947; sensitivity 100%, specificity 78.9%) and PTH (AUC 0.914; sensitivity 100%, specificity 73.7%) one week postparathyroidectomy. Evolution: follow-up 30±16.3 months: 50% normalized PTH and 8.3% had recurrence of hyperparathyroidism. Patients with PPNCHPPT less frequently received preoperative treatment with bisphosphonates and postoperative treatment with calcium salts. ConclusionsThis is the first study in our country that demonstrates a mean prevalence of PPNCHPPT, mainly related to a vitamin D deficiency and a probable resistance to the action of PTH, which can be predicted by the PTH/ACC ratio and PTH a week post-intervention and often evolves normalizing the PTH. We disagree with the etiological effect of hypercalciuria and the change in the PTH/calcemia regulation set point, and we acknowledge the scant treatment administered with calcium salts in the postoperative period.

A Cross-Sectional Study Examining the Parametric Thyroid Feedback Quantile Index and Its Relationship with Metabolic and Cardiovascular Diseases.

Background: The usual inverse correlation between thyrotropin (TSH) and thyroid hormone disappears in syndromes of central resistance to thyroid hormone, where both are high. TSH and thyroid hormone are also simultaneously high when there is an elevation of the set point of the thyroid regulation axis. This can be estimated with indices, such as the Parametric Thyroid Feedback Quantile-based Index (PTFQI), which was designed for the general population. The PTFQI is positively associated with diabetes prevalence, but association with other pathologies has not been yet explored. The aim of this project was to explore the potential relationship of the PTFQI with metabolic and cardiovascular disease in a sample of ambulatory adult patients from Spain. Methods: A cross-sectional study was carried out among the patients who underwent thyroid hormones measurement (6434 measurements from September to November 2018 in a central laboratory in Spain). We retrospectively reviewed clinical records of a subgroup of adults aged >18 years with normal TSH and free thyroxine (fT4) belonging to groups that represent extreme PTFQI (n = 661). Individuals with known conditions interfering the thyroid axis were excluded (remaining n = 296). Logistic and linear regression models adjusted for age and sex were used to calculate odds ratio (OR) of diseases and differences of clinical parameters, and 95% confidence intervals [CI]. Results: Across levels with higher PTFQI, there was an increase in the prevalence of type 2 diabetes (High vs. Low PTFQI OR: 2.88 [CI: 1.14-7.86], p-Trend = 0.02), ischemic heart disease (16.4% vs. 0%, unadjusted Haldane-Anscombe corrected OR: 23.90 [CI: 1.36-21.48], adjusted p-Trend = 0.04), atrial fibrillation (OR: 8.13 [CI: 1.33-158.20], p-Trend = 0.05), and hypertension (OR: 3.19 [CI: 1.14-9.94], p-Trend = 0.05). While the prevalence of type 2 diabetes was similarly associated with TSH and fT4, ischemic heart disease, atrial fibrillation, and hypertension were more strongly associated with the differences in fT4 values. Conclusions: Type 2 diabetes, ischemic heart disease, atrial fibrillation, and hypertension may be associated with a higher central regulation set point for thyroid hormone. These findings should be confirmed in other populations.

Total Antioxidant Capacity and Frailty in Older Men.

Frailty, a clinical syndrome characterized by multisystem dysregulation, has been associated with high levels of oxidative stress. We investigated the association between serum total antioxidant capacity (TAC) and frailty in older men. This cross-sectional study included 581 men (age 60–90 years) enrolled in the Geelong Osteoporosis Study. Frailty comprised at least three of unintentional weight loss, exhaustion, low physical activity, slowness, and weakness. Serum TAC was measured by quantitative colorimetric determination and expressed as uric acid equivalents (mM). Relationships between TAC (in SD units) and frailty were explored using multivariable logistic regression models. Sociodemographic, anthropometric, and lifestyle variables were tested as potential confounders and effect modifiers. A sensitivity analysis excluded participants (n = 145) in the upper quartile of TAC, who were likely to have hyperuricemia. Fifty (8.6%) men were frail. There was evidence that higher TAC levels were associated with increased likelihood of frailty (OR 1.34, 95% confidence interval [CI; 0.99, 1.80]), and this was attenuated after adjustment for age and body mass index (BMI; OR 1.26, 95% CI [0.93,1.71]). No effect modifiers or other confounders were identified. The sensitivity analysis revealed a positive association between TAC and frailty, before and after accounting for age and BMI (adjusted OR 1.79, 95% CI [1.01, 3.17] p = .038). These results suggest a positive association between TAC levels and frailty, supporting the hypothesis that this biomarker could be useful in identifying individuals at risk of frailty. We speculate that a milieu of heightened oxidative stress in frailty may elevate the oxidative stress regulatory set point, raising antioxidant activity. This warrants further investigation.

A comparison of lighting control strategies for open offices

Providing environmental control to users in multi-user offices has long being considered not done. One of the reasons is it was believed that personal control in an open office would rather create conflict among office users than bring benefits. However, a number of experimental studies conducted to explore the experience of personal control of lighting in open offices start building empirical evidence that can help more informed decision-making. This paper presents the results of the second field experiment conducted as part of a larger study exploring the experience of personal control in a multi-user open office context. The experiment showed that despite users having diverse lighting preferences, provision of control even in a multi-user office resulted in a higher satisfaction with the lighting environment than in an office with a fixed light level. The study evaluated three personal control strategies. The results did not deliver evidence of benefits of the control strategy “control set-point” in which the user selected light level was treated as a set-point for daylight regulation. The results showed that when the system remembered the last level set by the user it resulted in a smaller amount of user actions executed using personal control and the resulting lighting conditions in the office better reflected individual preferences compared to the “forgetting” strategy in which the system was resetting overnight to its default state. The results were significant only with respect to satisfaction with daylight in favor of the system remembering the user set light level.

Ln2NiO4+δ (Ln = La, Pr, Nd) coatings deposited by reactive magnetron sputtering as cathode material for intermediate temperature solid oxide fuel cell

This work focuses on the comparison of Ln-Ni-O coatings (Ln = La, Nd, Pr) deposited by reactive magnetron sputtering using Plasma Emission Monitoring (PEM) which allows high deposition rate. Each layer is deposited by different steps. The optimal regulation setpoint for oxide rare-earth deposition is determined and then the current dissipated on the nickel target is adjusted to obtain the convenient Ln/Ni ratio and to achieve the K2NiF4 structure. After an appropriate annealing treatment, all coatings exhibit crystalline structures, which depend on the Ln/Ni ratio. Due to the instability of Pr2NiO4 structure at intermediate temperatures, the crystallization step of praseodymium nickelate is performed at higher temperature than the other materials. This further thermal treatment implies a more porous structure. Each coating exhibits interesting properties. Electrical and electrochemical characterizations performed on these deposits prove better properties of the praseodymium nickelate coating.

Quality Integral Regulator

A pragmatic and practical device for process and product quality control in oil, petroleum, paper, manufacturing and food processing and manufacturing industries. The Quality Integral Regulator design is based on the mathematical process methodology and statistical process monitoring and feedback adjustment. A feedback control regulator algorithm is simulated under feedback control stability constraints to yield process control outputs in the form of number of adjustment intervals required to bring the output close to the target. The integral controller element in the regulator calculates the input adjustment required to bring the control error standard deviation of the outgoing product quality control variable close to the desired value (target) or the regulator set point. Statistical control procedures and process regulation schemes are formulated to minimise output product quality variance and maintain output quality variable at regulator set point. The quality integral regulator design, parameters, performance measures are explained in this book. The regulator can be implemented through modern computer parallel processing architectures for SISO and MIMO processes.

Effect of total pressure on La 2 NiO 4 coatings deposited by reactive magnetron sputtering using plasma emission monitoring

Abstract This work focuses on the structural, microstructural, electrical and electrochemical characterization of La–Ni–O coatings deposited by reactive magnetron sputtering under different argon partial pressures. Deposition was driven by Plasma Emission Monitoring system (PEM) which allows high deposition rate. For each pressure, the optimal regulation setpoint for lanthanum oxide deposition is determined and then the current dissipated on the nickel target is adjusted to obtain the convenient La/Ni ratio to achieve the K 2 NiF 4 structure. After an appropriate annealing treatment, coatings crystallize in the desired structure with more or less impurities. Increasing the device's pressure from 0.4 to 4.8 Pa produces more porous samples with different microstructures. Then, a coating with porosity gradient was built by using these four different total pressures. Its electrical performances were tested and allowed its utilization as cathode layer in intermediate temperature-solid oxide fuel cell (IT-SOFC). This modified architecture cathode allows better performances (71 mW·cm − 2 ) than dense cathode produced by the same technique (51 mW·cm − 2 ).

Nutritional ecology of obesity: from humans to companion animals.

We apply nutritional geometry, a framework for modelling the interactive effects of nutrients on animals, to help understand the role of modern environments in the obesity pandemic. Evidence suggests that humans regulate the intake of protein energy (PE) more strongly than non-protein energy (nPE), and consequently will over- and under-ingest nPE on diets with low or high PE, respectively. This pattern of macronutrient regulation has led to the protein leverage hypothesis, which proposes that the rise in obesity has been caused partly by a shift towards diets with reduced PE:nPE ratios relative to the set point for protein regulation. We discuss potential causes of this mismatch, including environmentally induced reductions in the protein density of the human diet and factors that might increase the regulatory set point for protein and hence exacerbate protein leverage. Economics--the high price of protein compared with fats and carbohydrates--is one factor that might contribute to the reduction of dietary protein concentrations. The possibility that rising atmospheric CO₂ levels could also play a role through reducing the PE:nPE ratios in plants and animals in the human food chain is discussed. Factors that reduce protein efficiency, for example by increasing the use of ingested amino acids in energy metabolism (hepatic gluconeogenesis), are highlighted as potential drivers of increased set points for protein regulation. We recommend that a similar approach is taken to understand the rise of obesity in other species, and identify some key gaps in the understanding of nutrient regulation in companion animals.

Synthesis and characterization of La2NiO4 + δ coatings deposited by reactive magnetron sputtering using plasma emission monitoring

This work focuses on the structural and electrical characterization of La–Ni–O coatings deposited by reactive magnetron sputtering using Plasma Emission Monitoring (PEM) which allows high deposition rate. The optimal regulation setpoint for lanthanum deposition is determined and then the current dissipated on the nickel target is adjusted to obtain the convenient La/Ni ratio to achieve the K2NiF4 structure. After an appropriate annealing treatment, all coatings exhibit crystalline structures that depend on the La/Ni ratio. Some cracks appear on samples deposited on alumina substrates depending to the argon flow rate and influence their electrical behavior.

Pro-TRH and pro-CRF expression in paraventricular nucleus of small litter-reared fasted adult rats

Neuroendocrine axes adapt to nutrient availability. During fasting, the function of the hypothalamus-pituitary-thyroid axis (HPT) is reduced, whereas that of the hypothalamus-pituitary-adrenal axis (HPA) is increased. Overfeeding-induced hyperleptinemia during lactation may alter the regulatory set point of neuroendocrine axes and their adaptability to fasting in adulthood. Hyperleptinemia is developed in rodents by litter size reduction during lactation; adult rats from small litters become overweight, but their paraventricular nucleus (PVN) TRH synthesis is unchanged. It is unclear whether peptide expression still responds to nutrient availability. PVN corticotropin-releasing factor (CRF) expression has not been evaluated in this model. We analyzed adaptability of HPT and HPA axes to fasting-induced low leptin levels of reduced-litter adult rats. Offspring litters were reduced to 2-3/dam (early-overfed) or maintained at 8/dam (controls, C). At 10 weeks old, a subset of animals from each group was fasted for 48 h and leptin, corticosterone, and thyroid hormones serum levels were analyzed. In brain, expressions of leptin receptor, NPY and SOCS3, were evaluated in arcuate nucleus, and those of proTRH and proCRF in PVN by real-time PCR. ProTRH expression in anterior and medial PVN subcompartments was assayed by in situ hybridization. Early-overfed adults developed hyperphagia and excessive weight, together with decreased proTRH expression in anterior PVN, supporting the anorexigenic effects of TRH. Early-overfed rats presented low PVN proTRH synthesis, whereas fasting did not induce a further reduction. Fasting-induced stress was unable to increase corticosterone levels, contributing to reduced body weight loss in early-overfed rats. We concluded that early overfeeding impaired the adaptability of HPT and HPA axes to excess weight and fasting in adults.

Adaptive Changes of the Insig1/SREBP1/SCD1 Set Point Help Adipose Tissue to Cope With Increased Storage Demands of Obesity

The epidemic of obesity imposes unprecedented challenges on human adipose tissue (WAT) storage capacity that may benefit from adaptive mechanisms to maintain adipocyte functionality. Here, we demonstrate that changes in the regulatory feedback set point control of Insig1/SREBP1 represent an adaptive response that preserves WAT lipid homeostasis in obese and insulin-resistant states. In our experiments, we show that Insig1 mRNA expression decreases in WAT from mice with obesity-associated insulin resistance and from morbidly obese humans and in in vitro models of adipocyte insulin resistance. Insig1 downregulation is part of an adaptive response that promotes the maintenance of SREBP1 maturation and facilitates lipogenesis and availability of appropriate levels of fatty acid unsaturation, partially compensating the antilipogenic effect associated with insulin resistance. We describe for the first time the existence of this adaptive mechanism in WAT, which involves Insig1/SREBP1 and preserves the degree of lipid unsaturation under conditions of obesity-induced insulin resistance. These adaptive mechanisms contribute to maintain lipid desaturation through preferential SCD1 regulation and facilitate fat storage in WAT, despite on-going metabolic stress.

Short communication: Glucose infusion into early postpartum cows defines an upper physiological set point for blood glucose and causes rapid and reversible changes in blood hormones and metabolites

Low blood glucose concentrations after calving are associated with infertility in postpartum dairy cows perhaps because glucose is a master regulator of hormones and metabolites that control reproductive processes. The hypothesis was that low blood glucose postpartum is caused by inadequate glucose entry rate relative to whole-body demand as opposed to the alternative possibility that postpartum cows have a lower regulatory set point for blood glucose. Eight early postpartum (10 to 25 d) dairy cows (5 Holstein and 3 Guernsey) were jugular catheterized. During the first 24h, cows were infused with physiological saline at 83.3mL/h. After 24h, the infusion solution was switched to 50% dextrose that was infused at a rate of 41.7mL/h (total daily glucose dose=500g). On d 3 and d 4, the rate of glucose infusion was increased to 83.3mL/h (daily dose=1,000g) and 125mL/h (daily dose=1,500g), respectively. On d 5, physiological saline was infused at 83.3mL/h. Blood was sampled hourly through a second jugular catheter (contralateral side) and analyzed for glucose, nonesterified fatty acids, β-hydroxybutyrate, insulin-like growth factor 1, and insulin. Blood glucose concentrations on d 1 (saline infusion) averaged 53.4±1.7mg/dL. Blood glucose concentrations increased on d 2 when cows were infused with 500g/d and increased further on d 3 when cows were infused with 1,000g of glucose/d. Increasing the infusion rate to 1,500g/d on d 4 did not cause a further increase in blood glucose concentrations. Based on a segmented regression analysis, the upper physiological set point for blood glucose was 72.1mg/dL. Both insulin and insulin-like growth factor 1 concentrations increased in response to glucose infusion and decreased when cows were infused with saline on d 5. Serum nonesterified fatty acids and β-hydroxybutyrate concentrations decreased in response to glucose infusion and rebounded upward on d 5 (saline infusion). In conclusion, early postpartum cows had circulating blood glucose concentrations that were well below the upper set point defined in this study (72.1mg/dL). Infusing approximately 1,000g of glucose daily increased blood glucose to the physiological set point and rapidly changed the hormonal and metabolic profile that typifies postpartum cows. The inability of the early postpartum cow to achieve an adequate entry rate for glucose relative to whole-body demand is a possible mechanism that links postpartum physiology and nutrition to reproduction in dairy cows.

Role of endothelin-1 in renal regulation of acid-base equilibrium in acidotic humans

Endothelin-1 inhibits collecting duct sodium reabsorption and stimulates proximal and distal tubule acidification in experimental animals both directly and indirectly via increased mineralocorticoid activity. Diet-induced acid loads have been shown to increase renal endothelin-1 activity, and it is hypothesized that increased dietary acid-induced endothelin-1 activity may be a causative progression factor in human renal insufficiency and that this might be reversed by provision of dietary alkali. We sought to clarify, in normal human volunteers, the role of endothelin-1 in renal acidification and to determine whether the effect is dependent on dietary sodium chloride. Acid-base equilibrium was studied in seven normal human volunteers with experimentally induced metabolic acidosis [NH(4)Cl 2.1 mmol·kg body weight (BW)(-1)·day(-1)] with and without inhibition of endogenous endothelin-1 activity by the endothelin A/B-receptor antagonist bosentan (125 BID p.o./day) both during dietary NaCl restriction (20 mmol/day) and NaCl repletion (2 mmol NaCl·kg BW(-1)·day(-1)). During NaCl restriction, but not in the NaCl replete state, bosentan significantly increased renal net acid excretion in association with stimulation of ammoniagenesis resulting in a significantly increased plasma bicarbonate concentration (19.0 ± 0.8 to 20.1 ± 0.9 mmol/l) despite a decrease in mineralocorticoid activity and an increase in endogenous acid production. In pre-existing human metabolic acidosis, endothelin-1 activity worsens acidosis by decreasing the set-point for renal regulation of plasma bicarbonate concentration, but only when dietary NaCl provision is restricted.

Coherence: A Novel Nonpharmacological Modality for Lowering Blood Pressure in Hypertensive Patients

This study examined the efficacy of teaching emotional self-regulation techniques supported by heart rhythm coherence training (emWave Personal Stress Reliever) as a means to quickly lower blood pressure (BP) in patients diagnosed with hypertension. Previous studies have demonstrated systemic reductions in BP in both high stress populations and patients diagnosed with hypertension using this approach, but to the best of our knowledge, an investigation of their ability to produce immediate reductions in BP had not been published in the medical literature.The study was a randomized controlled design with 62 hypertensive participants who were divided into three groups. Group 1 was taking hypertensive medication, was taught self-regulation technique, and used heart rate variability coherence (HRVC) training devices. Group 2 was not yet taking medication and was trained in the same intervention. Group 3 was taking hypertensive medication but did not receive the intervention and was instructed to relax between the BP assessments.An analysis of covariates was conducted to compare the effectiveness of three different interventions on reducing the participants' BP. The use of the self-regulation technique and the HRVC-monitoring device was associated with a significantly greater reduction in mean arterial pressure in the two groups who used the intervention as compared with the relaxation-plus-medication group. Additionally, the group not taking medication that used the intervention also had a significantly greater reduction in systolic BP than the relaxation- plus-medication group.These results suggest that self-regulation techniques that incorporate the intentional generation of positive emotions to facilitate a shift into the psychophysiological coherence state are an effective approach to lowering BP. This approach to reducing BP should be considered a simple and effective approach that can easily be taught to patients to quickly lower their BP in stressful situations. The technique should be especially useful when hypertensive patients are experiencing stressful emotions or reactions to stressors. It is possible that the BP reductions associated with the use of the technique leads to a change in the physiological set-point for homeostatic regulation of BP. Further studies should examine if large scale implementations of such heart-based coherence techniques could have a significant impact on reducing risk of mortality and morbidity in hypertensive patients.

Parametric analysis of pressure control system for Lungmen nuclear power plant

Pressure control systems (PCSs) are applied on nuclear reactors to stabilize the system pressure and reactor steam flow during normal operation, and control the system pressure smoothly when the reactor steam generation exceeds the steam flow used by turbine. The purpose of this study was to investigate the dynamic response of PCS for Lungmen nuclear power plant. The thermal-hydraulic analysis code, RETRAN-3D, was applied for the construction of Lungmen reactor model and the associated control systems, and the dynamic response of pressure control system was evaluated by means of the perturbations induced by the step change of pressure regulator setpoint. The important parameters such as values of overshooting and decay ratios were calculated by 121 code runs with different lead-lag time constants, discovering the effect of lead-lag controller on dynamic response. This parametric study indicates that the performance of PCS may be enhanced by adjustment of lead-lag time constants. Furthermore, an optimization algorithm will be coupled with Lungmen RETRAN model for optimization analysis, searching optimal lead-lag constants.

High cell density growth of High Five suspension cells in DO-controlled wave-mixed bioreactors

Insect cells such as High Five cells used in the manufacture of biopharmaceuticals are best grown in wave-mixed bioreactors (1). This is due to the continual blending of foam with the culture medium which results from the wave-induced mixing and permanent renewal of the medium surface. Even the addition of an antifoam agent is not required. Process conditions which ensure maximum High Five cell densities and which have been reported to be about 8 x 106 cells x mL-1 (2) were determined in Biostat CultiBag RM50 optical experiments for batch mode and 1 L culture volume. Seed inoculum for these experiments was generated in single-use shake flasks (Corning) incubated in an Infors`Multitron shaker (27°C, 100 rpm, 25 mm shaking diameter). Biostat CultiBag RM50 optical was controlled in four different modes: non-pH- and non-DO-controlled, DO- controlled, pH-controlled, DO- as well as pH-controlled. The DO level was guaranteed by increasing the rocking rate up to 28 rpm and, if required by addition of pure oxygen. In process control was supplemented with off-line analyses of cell density, viability, metabolites (glucose, glutamine, glutamate, lactate, ammonium) and pH. While the influence of the type of bioreactor`s control on the maximum growth rate (0.041-0.044 h-1) and doubling time (15.6-17.7 h) was negligible, maximum cell densities were achieved with DO regulation (set point 50%). Maximum cell densities ranged between 8.2 and 9.4 x 106 cells x mL-1 and represent the highest values described for High Five cells so far in the literature. They are 35% higher compared to those seen in pH-controlled and non-controlled experiments. Controlling both DO and pH level did not lead to any further improvement of cell growth i.e. the range of growth parameter values was the same as that observed in the previous experiments. For High Five cell-based biopharmaceuticals this knowledge enables optimized seed inoculum/seed train production in wave-mixed bag bioreactors.

Synergistic effects of elevated CO2 and temperature on the metabolic scope and activity in a shallow-water coastal decapod (Metapenaeus joyneri; Crustacea: Penaeidae)

AbstractDissanayake, A., and Ishimatsu, A. 2011. Synergistic effects of elevated CO2 and temperature on the metabolic scope and activity in a shallow-water coastal decapod (Metapenaeus joyneri; Crustacea: Penaeidae). – ICES Journal of Marine Science, 68: 1147–1154. The physical drivers of climate change (increased CO2; hypercapnia and temperature) are causing increasing warming of the earth's oceans, elevating oceanic CO2 concentrations, and acidity. Elucidating possible climate change impacts on marine biota is of paramount importance, because generally, invertebrates are more sensitive to hypercapnia than fish. This study addresses impacts of synergistic factors; hypercapnia and temperature on osmoregulation, acid–base balance, and resting and active metabolism (assessed as oxygen consumption rates) and behavioural performance in a model nektonic crustacean. Metapenaeus joyneri exposed to both hypercapnia (1 kPa) at two temperatures (15 and 20°C) demonstrated significant physiological effects, i.e. new regulatory set points (lower haemolymph osmolality and higher pH, i.e. alkalosis) and reduced metabolic scope (MS), compared with control individuals (normocapnia, 0.04 kPa). Behavioural effects included a significant 30% reduction in swimming ability and may be the result of reduced MS (i.e. difference between active and routine metabolism). Synergistic factors may cause organisms to shift energy utilization towards up-regulation of maintenance functions (i.e. osmoregulatory ability) resulting in a decrease in both aerobic scope and energy-demanding activities. Laboratory-derived evidence elucidating the impacts in key model groups is of paramount importance, if we are to improve our knowledge of physiological effects of synergistic climate change factors.

Influence of Initial State on Position Regulation of Hysteretic Actuators

Actuators made from so-called smart materials have been proposed in the literature, for use in shape control of various surfaces. At the lowest level, this shape control problem can be thought of as a distributed regulation problem. Because of the hysteresis nonlinearity present in these actuators, there are an infinite number of input values corresponding to a particular output regulation setpoint. One might then ask the question, not relevant to memory-less systems, whether there is some advantage to regulating about one of these states in particular. This work proposes, based on observations from the Preisach model, that for any desired output there is one state in particular at which the system has a better natural (open-loop) rejection of uniformly-distributed noise at its input. This proposition is tested in both simulation and experiment. The reachability of this so-called `neutral state' is discussed, as is the generation of an input to drive the system to the appropriate neutral state. It is demonstrated that closed-loop regulation schemes will also benefit from starting in the appropriate neutral state, requiring less control effort for regulation.

Fetal Programming

Research on young animals and humans has demonstrated the critical importance of the fetal stage as a formative period in normal development. However, the significance of these findings has not always been incorporated into our thinking when trying to elucidate the origins of health and disease. It is not only that babies react to the state of the mother and to salient environmental events while still in the uterus. This stimulation and priming seems to be essential for guiding the optimal maturation of the nervous, endocrine, and immune systems. Experiences during prenatal life also program the regulatory set points that will govern physiology in adulthood. During this malleable maturational phase, these biological processes should be viewed as flexible “learning systems” that guide the developmental trajectory toward health or derail it toward pathology. Our studies on infant primates have shown that the competence of their immune responses and the structure and activity of certain brain regions, as well as many aspects of behavior and emotional reactivity, are strongly affected by the pregnancy conditions of their mothers.