The purpose of this paper is to disclose the design techniques and experimental methodologies for the stabilization of X-band phase locked loop (PLL) phase noise performance during random vibration environment. Phase noise performance of PLL based unit under test (UUT) is very prone to disturbance occurred in random vibration profile frequency spectrum. UUT self-resonance plays vital role in occurrence of disturbance in random vibration profile. The stabilization of phase noise performance during dynamic (random vibration) condition is achieved by following methodologies, i.e. vibration-isolator compensation technique, purification tactic of crystal reference of PLL and spatial location analysis for mounting of crystal reference. Spatial analysis helps to filter out UUT self-resonance from frequency spectrum of random vibration profile which ultimately leads to reduction of frequency resonance pickups during random vibration testing.
From its origins, the concept of desertification has been controversial. The prevailing confusion between two desertification visions, one that considers it as the expansion of deserts and another that denotes its anthropogenic component, has been transferred to society. Here we illustrate misunderstandings about desertification using a very illustrative case from the Tabernas-Sorbas Basin (Almeria, Spain), where striking badlands that are often used as an image of desertification coexist with an intensive olive agriculture that is deteriorating irreversibly the only oasis in continental Europe, Los Molinos spring. The olive tree is a traditional Mediterranean dryland crop and until the 1950s only about 200 ha were irrigated. However, the profitability of the crop has caused irrigation to expand to 4,400 ha in the last two decades. The process of intensification has been reinforced giving way to super-intensive irrigation, which involves going from 210 to 1,550 trees/ha and that in a few years already occupies more than 1,500 ha. The effects on the water balance of the aquifer feeding these crops have been severe and the flow of the Los Molinos spring has gone from more than 40 L/s for the period 1970-2000 to the current 7.28 L/s. By unraveling the mechanisms of land degradation, we were able to detect its main drivers in the study area and, with them, to propose management actions to achieve a more sustainable use of resources and to combat desertification.
1. The reduction of plant diversity following eutrophication threatens many ecosystems worldwide. Yet, the mechanisms by which species are lost following nutrient enrichment are still not completely understood, nor are the details of when such mechanisms act during the growing season, which hampers understanding and the development of mitigation strategies. 2. Using a common garden competition experiment, we found that early-season differences in growth rates among five perennial grass species measured in monoculture predicted short-term competitive dominance in pairwise combinations and that this effect was stronger under a fertilisation treatment. 3. We also examined the role of early-season growth rate in determining the outcome of competition along an experimental nutrient gradient in an alpine meadow. Early differences in growth rate between species predicted short-term competitive dominance under both ambient and fertilized conditions and competitive exclusion under fertilized conditions. 4. The results of these two studies suggests that plant species growing faster during the early stage of the growing season gain a competitive advantage over species that initially grow more slowly, and that this advantage is magnified under fertilisation. This finding is consistent with the theory of asymmetric competition for light in which fast-growing species can intercept incident light and hence outcompete and exclude slower-growing (and hence shorter) species. We predict that the current chronic nutrient inputs into many terrestrial ecosystems worldwide will reduce plant diversity and maintain low biodiversity state by continuously favouring fast-growing species. Biodiversity management strategies should focus on controlling nutrient inputs and reducing the growth of fast-growing species early in the season.
In this study, the CO2 gas absorption process has been investigated modeling in order to find suitable adsorbent, as well as determination of the solubility and mass transfer mechanism. To calculate the solubility of CO2 in a solution of triethanolamine and piperazine, the CPA state equation will be used to predict the properties of the system. The results show that with increasing pressure, the absorption of Co2 in the gas phase increases due to the increase of the CO2 absorption of density gradient. By increasing the temperature, the amount of CO2 absorbed in the adsorbent solution decreases, due to the calorific of the Co2 absorption by the use of an amine absorbent solution. Also, by increasing the concentration of piperazine in the amine absorbent solution, the amount of CO2 absorption increases as a result of increasing the reaction rate of the amine solution with CO2 in the presence of piperazine. The highest overall error rate obtained from the reported data for operating pressure, temperature and piperazine concentrations variable is 7.3%, 7.4% and 4%, which is considered an acceptable error rate, respectively.
Tropical montane cloud forests (TMCF) are recognized for their capacity to maintain high dry-season baseflow, and a host of other, ecosystem services. Despite their importance, they are endangered with a multidirectional array of land use changes, including conversion to pasture and crops such as coffee, while there are places where forest is being recovered. However, little is known about the effects of this complex dynamic on catchment hydrology. We investigated the effect of land use on rainfall-runoff response in five neighboring headwater micro-catchments in central Veracruz, Mexico, by comparing primary TMCF (PF), young (20 yr-old) and intermediate (40 yr-old) naturally regenerating TMCF (YF and IF, respectively), shaded coffee (SC), and an intensively grazed pasture (IP). We used a 4-year record of high-resolution rainfall and streamflow (10 min) data, collected from 2015 to 2019. These data were analyzed via hydrologic metrics and statistical tests. Results showed no statistical difference in the regulation capacity of high flows after 20 years of natural regeneration, compared to the PF. In terms of baseflow sustenance, our results suggested that PF and IF better promote this hydrological service than the other land uses, although all the catchments showed high mean annual low flows. SC exhibited a high capacity to modulate peak flows comparable to that of PF, and an intermediate capacity to sustain baseflow, suggesting that the integrated functioning of this catchment was largely preserved. Finally, we found that 40 years of pasture management can decrease the soil hydraulic properties in the area, causing a fivefold increase in the peak discharge response, and a much lower baseflow maintenance compared to PF.
Population dynamics models combine density-dependence and environmental effects. Ignoring sampling uncertainty might lead to biased estimation of the strength of density-dependence. This is typically addressed using state-space model approaches, which integrate sampling error and population process estimates. Such models seldom include an explicit link between the sampling procedures and the true abundance, which is common in capture-recapture settings. However, many of the models proposed to estimate abundance in the presence of heterogeneity lead to incomplete likelihood functions and cannot be straightforwardly included in state-space models. We assessed the importance of estimating sampling error explicitly by taking an intermediate approach between ignoring uncertainty in abundance estimates and fully specified state-space models for density-dependence estimation based on autoregressive processes. First, we estimated individual capture probabilities based on a heterogeneity model, using a conditional multinomial likelihood, followed by a Horvitz-Thompson estimate for abundance. Second, we estimated coefficients of autoregressive models for the log abundance. Inference was performed using the methodology of integrated nested Laplace approximation (INLA). We performed an extensive simulation study to compare our approach with estimates disregarding capture history information, and using R-package VGAM, for different parameter specifications. The methods were then applied to a real dataset of gray-sided voles Myodes rufocanus from Northern Norway. We found that density-dependence estimation was improved when explicitly modelling sampling error in scenarios with low innovation variances, in which differences in coverage reached up to 8% in estimating the coefficients of the autoregressive processes. In this case, the bias also increased assuming a Poisson distribution in the observational model. For high innovation variances, the differences between methods were small and it appeared less important to model heterogeneity.
The onset of acute illness may be accompanied by a profound sense of disorientation for patients. Addressing this vulnerability is a key part of a physician’s purview, yet well-intended efforts to do so may be impeded by myriad competing tasks in clinical practice. Resolving this dilemma goes beyond appealing to altruism, as its limitless demands may lead to physician burnout, disillusionment, and a narrowed focus on the biomedical aspects of care in the interest of self-preservation. The authors propose an ethic of hospitality that may better guide physicians in attending to the comprehensive needs of patients that have entered “the kingdom of the sick”. Using philosophical methods, the authors explore what compels people to present to emergent medical attention and why altruism may not offer physicians a sustainable way to address the vulnerabilities that occur in such situations. They then present the concept of hospitality from a Derridean perspective and use it to interpret a narrative case of an on-call paediatrician caring for an infant with bronchiolitis to demonstrate how this approach may be practically implemented in the acute care hospital context. Hospitality allows physicians to acknowledge that clinical presentations that are routine in their world may be disorienting and frightening to patients experiencing them acutely. Further, it recognizes that the vulnerability that accompanies acute illness may be compounded by the unfamiliarity of the hospital environment in which patients have sought support. While it is unlikely that anything physicians do will make the hospital a place where patients and caregivers will desire to be, hospitality may focus their efforts upon making it less unwelcoming. Specifically, it offers an orientation that supports patients in navigating the disorienting and unfamiliar terrains of acute illness, the hospital setting in which help is sought, and engagement with the health care system writ large.
Human pressure on the water resources provided by natural wetlands has intensified in Brazil due to an increase in agricultural land equipped with irrigation. However, the amount of water stored in these areas, and its contribution to aquifer recharge is unknown. The objectives of this study were to determine the amount of water that can be retained in a natural wetland surrounded by farmland and to propose a model of groundwater recharge. We used remote sensing techniques involving Unmanned Aerial Vehicle (UAV) to map the area and highlight the wetland internal morphology, using RGB orthomosaic and its respective digital surface model. According to the topography of the study area three compartments were defined. Compartment 1, corresponding to the external border of the wetland, can store 313,121.00 m³ of water; compartment 2 and 3 can store 85,923.20 m³ and 17,952.10 m³, respectively. The 2D inversion and a pseudo-3D model produced from Electrical Resistivity Tomography (ETR) data were used to visualize the subsurface geologic structure and hydrologic flow paths. Our results showed the direct interactions between groundwater (GW) and surface water (SW) in the center of the wetland (compartment 3), which constitutes the aquifer recharge zone with vertical infiltration. As the depth increases, infiltration and water flow deviate laterally in the southwest and northeast direction. The wetland is characterized as an unconfined aquifer that plays an important role in the hydrogeological dynamics of the catchment. Remotely sensed images allied with geophysical techniques allow complete surface and subsurface imaging and offers visual tools that contribute to understanding the hydrodynamic of an area.
In Belgium, IWVA uses Managed Aquifer Recharge (MAR) to recharge the aquifer with treated wastewater generated from the communities to sustain the potable water supply on the Belgian coast. This MAR facility is faced with a challenge of reduced infiltration rates during the winter season when pond water temperatures near 4 °C. This study involves the identification of the predominant factor influencing the rate of infiltration through the pond bed. Several factors including pumping rates, natural recharge, tidal influences of the North Sea and pond-water temperature were identified as potential causes for variation of the recharge rate. Correlation statistics and linear regression analysis were used to determine the sensitivity of the infiltration rate to the aforementioned factors. Two groundwater flow models were developed in visual MODFLOW to simulate the water movement under the pond bed and to obtain the differences in flux to track the effects of variation of hydraulic conductivity during the two seasons. A 32 % reduction in vertical hydraulic gradient in the top portion of the aquifer was observed in winter causing the recharge rates to fluctuate. Results showed that water temperature caused a 30 % increase in hydraulic conductivity in summer as compared to winter and has the maximum impact on infiltration rate. Cyclic variations in water viscosity, occurring because of seasonal temperature changes, influence the saturated hydraulic conductivity of the pond bed. Results from the models confirm the impact on infiltration rate by temperature influenced hydraulic conductivity.
Ecological processes in food webs depend on species interactions. By identifying broad-scaled interaction patterns, important information on species ecological roles may be revealed. Here, we use the group model to examine how spatial resolution and proximity influence the group structure. We examine a dataset from the Barents Sea, with species occurrences for both the whole region and 25 subregions. Specifically, we test how the group structure in the networks differ comparing i) the regional metaweb to subregions and ii) subregion to subregion. We find that more than half the species in the metaweb change groups when compared to subregions. Between subregions, networks with similar group structure are usually spatially related. Interestingly, although species overlap is important for similarity in group structure, there are notable exceptions. Our results highlight that species ecological roles differ depending on fine-scaled differences in patterns of interactions, and that local network characteristics are important to consider.
Endotoxins are considered as the major contributors to the pyrogenic response observed with contaminated pharmaceutical products. Recombinant biopharmaceutical products are manufactured using living organisms, including gram-negative bacteria. Upon the death of a gram-negative bacteria, endotoxins (also known as lipopolysaccharides; LPS) in the outer cell membrane are released into the lysate where it can interact with and form bonds with biomolecules, including target therapeutic compounds. Endotoxin contamination of biologic products may also occur through water, raw materials such as excipients, media, additives, sera, equipment, containers closure systems, and expression systems used in manufacturing. The manufacturing process is therefore in critical need to reduce and remove endotoxins by monitoring raw materials and in-process intermediates at critical steps, in addition to final drug product release testing. In this review, a discussion regarding the progression of endotoxin detection techniques, from crude to refined are presented. We provide a brief overview of the upstream processed used to manufacture therapeutic products and then discuss various downstream purification techniques widely used to purify the products off endotoxins. Finally, we investigate the effectiveness of endotoxin purification processes, both from a perspective of precision as well as cost-effectiveness.
The FAO Water Productivity Open Access Portal (WaPOR) offers continuous actual evapotranspiration and interception (ETIa-WPR) data at a 10-day basis across Africa and the Middle East from 2009 onwards at three spatial resolutions. The continental level (250m) covers Africa and the Middle East (L1). The national level (100m) covers 21 countries and four river basins (L2). The third level (30m) covers eight irrigation areas (L3). To quantify the uncertainty of WaPOR version 2 (V2.0) ETIa-WPR in Africa, we used a number of validation methods. We checked the physical consistency against water availability and the long term water balance and then verify the continental spatial and temporal trends for the major climates in Africa. We directly validated ETIa-WPR against in-situ data of 14 eddy covariance stations (EC). Finally, we checked the level consistency between the different spatial resolutions. Our findings indicate that ETIa-WPR is performing well, but with some noticeable overestimation. The ETIa-WPR is showing expected spatial and temporal consistency with respect to climate classes. ETIa-WPR shows mixed results at point scale as compared to EC flux towers with an overall R2 of 0.61, and a root mean square error of 1.04 mm/day. The level consistency is very high between L1 and L2. However, the consistency between L1 and L3 varies significantly between irrigation areas. In rainfed areas, the ETIa-WPR is overestimating at low ETIa-WPR and underestimating when ETIa is high. In irrigated areas, ETIa-WPR values appear to be consistently overestimating ETa. The soil moisture content, the input of quality layers and local advection effects were some of the identified causes. The quality assessment of ETIa-WPR product is enhanced by combining multiple evaluation methods. Based on the results, the ETIa-WaPOR dataset is of enough quality to contribute to the understanding and monitoring of local and continental water processes and water management.
Local correlation methods rely on the assumption that electronic correlation is nearsighted. In this work, we develop a method to alleviate this assumption. The first step is to approximately decompose the electron correlation to the nearsighted and farsighted components based on the wavelength decomposition of electron correlation by Langreth and Perdew. The nearsighted component is then calculated using the recently developed embedded cluster density approximation (ECDA) which is a local correlation method formulated in the context of density functional theory. The farsighted component is calculated based on the system’s Kohn-Sham orbitals. The accuracy of this new method depends on the quality of the decomposition. We examined the method’s accuracy by patching the random phase approximation (RPA) correlation energy in a H₂₄ chain in which the electron correlation is highly nonlocal. This new method predicts bond stretching energies, RPA correlation potential, and Kohn-Sham eigenvalues in good agreement with the benchmarks. Our results demonstrate the importance of including the farsighted part of electron correlation for studying systems having nonlocal correlations.
We report on the development of a new model of alveolar air-tissue interface consisting of an array of suspended hexagonal monolayers of gelatin nanofibers supported by microframes and a microfluidic device for the patch integration. The suspended monolayers are deformed to a central displacement of 40-80 μm at the air-liquid interface by application of air pressure in the range of 200-1000 Pa. With respect to the diameter of the monolayers that is 500 μm, this displacement corresponds to a linear strain of 2-10% in agreement with the physiological strain range in the lung alveoli. The culture of A549 cells on the monolayers for an incubation time 1-3 days showed viability in the model. We exerted a periodic strain of 5% at a frequency of 0.2 Hz during 1 hour to the cells. We found that the cells were strongly coupled to the nanofibers, but the strain reduced the coupling and induced remodeling of the actin cytoskeleton, which led to a better tissue formation. Our model can serve as a versatile tool in lung investigations such as in inhalation toxicology and therapy.
Manually collected snow data are often considered as ground truth for many applications such as climatological or hydrological studies. However, there are many sources of uncertainty that are not quantified in detail. For the determination of water equivalent of snow cover (SWE), different snow core samplers and scales are used, but they are all based on the same measurement principle. We conducted two field campaigns with 9 samplers commonly used in observational measurements and research in Europe and northern America to better quantify uncertainties when measuring depth, density and SWE with core samplers. During the first campaign, as a first approach to distinguish snow variability measured at the plot and at the point scale, repeated measurements were taken along two 20 m long snow pits. The results revealed a much higher variability of SWE at the plot scale (resulting from both natural variability and instrumental bias) compared to repeated measurements at the same spot (resulting mostly from error induced by observers or very small scale variability of snow depth). The exceptionally homogeneous snowpack found in the second campaign permitted to almost neglect the natural variability of the snowpack properties and focus on the separation between instrumental bias and error induced by observers. Under such measurement conditions, the uncertainty in bulk snow density estimation is about 5% for an individual instrument and is close to 10% among different instruments. Results confirmed that instrumental bias exceeded both the natural variability and the error induced by observers, even in the case when observers were not familiar with a given snow core sampler.
The Irtysh River is the main water resource of eastern Kazakhstan and its upper basin is severely affected by spring floods each year, primarily as a result of snowmelt. Knowledge of the large scale processes that influence the timing of these snow-induced floods is currently lacking, but critical for the management of water resources in the area. In this study, we evaluated the variability in winter-spring snow cover in five major sub-basins of the Upper Irtysh basin between 2000 and 2017 as a possible explanatory factor of spring flood events, assessing the time of peak snow cover depletion rate and snow cover disappearance from the MODIS MOD10A2 dataset. We found that on average, peak snow cover retreat occurs between 22 March and 14 April depending on the basin, with large inter-annual variations but no clear trend over the observation period. In contrast, the annual peak snow cover depletion rate displays a weak increasing trend over the study period and exceeded 5900 km2 day-1 in 2017. The timing of snow disappearance in spring shows significant correlations of up to 0.82 for the largest basin with winter indices of the Arctic Oscillation over the region. The primary driver is the impact of the large scale pressure anomalies upon the mean spring (MAM) air temperatures and resultant timing of snow cover disappearance, particularly at elevations 500-2000 m above sea level. This suggests a lagged effect of this atmospheric circulation pattern in spring snow cover retreat. The winter Arctic Oscillation index could therefore be incorporated into long-term runoff forecasts for the Irtysh. Our approach is easily transferable to other similar catchments, and could support flood management strategies in Kazakhstan and other countries.
Clinical use of pancreatic beta islets for regenerative medicine applications requires mass production of functional cells. Current technologies are insufficient for large-scale production in a cost-efficient manner. Here, we evaluate advantages of a porous cellulose scaffold and demonstrate scale-up to a wicking-matrix bioreactor as a platform for culture of human endocrine cells. Scaffold modifications were evaluated in a multi-well platform to find the optimum surface condition for pancreatic cell expansion followed by bioreactor culture to confirm suitability. Preceding scale-up, cell morphology, viability and proliferation of primary pancreatic cells were evaluated. Two optimal surface modifications were chosen and evaluated further for insulin secretion, cell morphology and viable cell density for human induced pluripotent stem cell-derived pancreatic cells at different stages of differentiation. Scale-up was accomplished with uncoated, amine-modified cellulose in a miniature bioreactor, and insulin secretion and cell metabolic profiles were determined for 13 days. We achieved 10-fold cell expansion in the bioreactor along with a significant increase in insulin secretion compared with cultures on tissue-culture plastic. Our findings define a new method for expansion of pancreatic cells on wicking-matrix cellulose platform to advance cell therapy biomanufacturing for diabetes.
Rationale, aims and objectives. Applying traditional industrial Quality Improvement (QI) methodologies to primary care is often inappropriate because primary care is best thought of as a network of highly interconnected agents in a complex adaptive system (CAS) that is particularly responsive to bottom-up rather than top-down management approaches. We report on a demonstration case study of improvements made in the Family Health Center (FHC) of the JPS Health Network in a refugee patient population that illustrate features of QI in a CAS framework as opposed to a traditional QI approach. Methods. We report on changes in health system utilization by new refugee patients of the FHC from 2016-2017 and summarize relevant theoretical understandings of quality management in complex adaptive systems. Results. Applying CAS principles in the FHC, utilization of the Emergency Department and Urgent Care by newly arrived refugee patients before their first clinic visit was reduced by more than half (total visits decreased from 31% to 14% of the refugee patients). Our review of the literature demonstrates that traditional top-down QI processes are most often unsuccessful in improving even a few single-disease metrics, and increases clinician burnout and penalizes clinicians who care for vulnerable patients. Improvement in a CAS occurs when front-line clinicians identify care gaps and are given the flexibility to learn and self-organize to enable new care processes to emerge, which are created from bottom-up leadership that utilize existing interdependencies made more sustainable as front-line clinicians use sensemaking to improve care processes. Conclusions and future directions. Recent reforms announced in primary care in Scotland, a few examples in the medical literature, and statements from some healthcare system leaders are examples of early adapters who are applying the principles of CAS to their QI efforts. Such initiatives and our example provide models for others to follow.