368 research outputs found
Design and Implementation of a Compact Automated Spirulina Cultivation System for Households
Spirulina is considered to be the most nutritious whole food source in nature. It is promoted as a dietary supplement and an active ingredient in functional foods. Factors such as conflicts, supply chain disruptions, and economic fallout are driving food prices to unprecedented levels. Low- and middle-income populations are affected by these rising costs. The design and implementation of a compact Spirulina cultivation system to be used in the household is presented in this paper. The system contains light, temperature, pH, and turbidity sensors. All sensors are connected to microcontrollers which activate a heater, air pump, mixing pump, pool fall pump, and two LEDs according to the readings received to ensure proper and continuous growth of Spirulina. The proposed system is user-friendly, economical, and can be easily stored and operated at homes to stimulate and monitor the growth of Spirulina. The primary objective of the proposed compact cultivation system is to furnish the necessary tools for generating a nutritionally valuable food source on a smaller scale, specifically within households, at a relatively affordable cost
Asymmetric Autocorrelation Function To Resolve Directional Ambiguity In PIV Images
ABSTRACT Autocorrelation of a double-exposed image, unlike cross-correlation between two images, produces a correlation function that i
Diffeomorphic random sampling using optimal information transport
In this article we explore an algorithm for diffeomorphic random sampling of
nonuniform probability distributions on Riemannian manifolds. The algorithm is
based on optimal information transport (OIT)---an analogue of optimal mass
transport (OMT). Our framework uses the deep geometric connections between the
Fisher-Rao metric on the space of probability densities and the right-invariant
information metric on the group of diffeomorphisms. The resulting sampling
algorithm is a promising alternative to OMT, in particular as our formulation
is semi-explicit, free of the nonlinear Monge--Ampere equation. Compared to
Markov Chain Monte Carlo methods, we expect our algorithm to stand up well when
a large number of samples from a low dimensional nonuniform distribution is
needed.Comment: 8 pages, 3 figure
Multilevel Sequential Monte Carlo with Dimension-Independent Likelihood-Informed Proposals
In this article we develop a new sequential Monte Carlo method for multilevel Monte Carlo estimation.
In particular, the method can be used to estimate expectations with respect to a target
probability distribution over an infinite-dimensional and noncompact space—as produced, for example,
by a Bayesian inverse problem with a Gaussian random field prior. Under suitable assumptions
the MLSMC method has the optimal O(ε
−2
) bound on the cost to obtain a mean-square error of
O(ε
2
). The algorithm is accelerated by dimension-independent likelihood-informed proposals [T. Cui,
K. J. Law, and Y. M. Marzouk, (2016), J. Comput. Phys., 304, pp. 109–137] designed for Gaussian
priors, leveraging a novel variation which uses empirical covariance information in lieu of Hessian
information, hence eliminating the requirement for gradient evaluations. The efficiency of the algorithm
is illustrated on two examples: (i) inversion of noisy pressure measurements in a PDE model
of Darcy flow to recover the posterior distribution of the permeability field and (ii) inversion of noisy
measurements of the solution of an SDE to recover the posterior path measure
Design and Implementation of a Compact Automated Spirulina Cultivation System for Households
Spirulina is considered to be the most nutritious whole food source in nature. It is promoted as a dietary supplement and an active ingredient in functional foods. Factors such as conflicts, supply chain disruptions, and economic fallout are driving food prices to unprecedented levels. Low- and middle-income populations are affected by these rising costs. The design and implementation of a compact Spirulina cultivation system to be used in the household is presented in this paper. The system contains light, temperature, pH, and turbidity sensors. All sensors are connected to microcontrollers which activate a heater, air pump, mixing pump, pool fall pump, and two LEDs according to the readings received to ensure proper and continuous growth of Spirulina. The proposed system is user-friendly, economical, and can be easily stored and operated at homes to stimulate and monitor the growth of Spirulina. The primary objective of the proposed compact cultivation system is to furnish the necessary tools for generating a nutritionally valuable food source on a smaller scale, specifically within households, at a relatively affordable cost
Fabrication and characterization of dual function nanoscale pH-scanning ion conductance microscopy (SICM) probes for high resolution pH mapping
The easy fabrication and use of nanoscale dual function pH-scanning ion conductance microscopy (SICM) probes is reported. These probes incorporate an iridium oxide coated carbon electrode for pH measurement and an SICM barrel for distance control, enabling simultaneous pH and topography mapping. These pH-SICM probes were fabricated rapidly from laser pulled theta quartz pipets, with the pH electrode prepared by in situ carbon filling of one of the barrels by the pyrolytic decomposition of butane, followed by electrodeposition of a thin layer of hydrous iridium oxide. The other barrel was filled with an electrolyte solution and Ag/AgCl electrode as part of a conductance cell for SICM. The fabricated probes, with pH and SICM sensing elements typically on the 100 nm scale, were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and various electrochemical measurements. They showed a linear super-Nernstian pH response over a range of pH (pH 2–10). The capability of the pH-SICM probe was demonstrated by detecting both pH and topographical changes during the dissolution of a calcite microcrystal in aqueous solution. This system illustrates the quantitative nature of pH-SICM imaging, because the dissolution process changes the crystal height and interfacial pH (compared to bulk), and each is sensitive to the rate. Both measurements reveal similar dissolution rates, which are in agreement with previously reported literature values measured by classical bulk methods
Factors associated with depression and anxiety in the adult population of Qatar after the first COVID-19 wave: a cross-sectional study
There is limited data from Arabic-speaking countries on risk factors for depression and anxiety during the COVID-19 pandemic. Country-specific data is necessary given differences in culture, demographics, and COVID-19 infection and mortality rates. The main purpose of the study is to identify the factors associated with symptoms of depression-anxiety in the adult population of Qatar during the first year of the COVID-19 pandemic. We conducted a cross-sectional online survey in Qatar between July and December 2020 after Qatar’s first COVID-19 wave and before the beginning of the second wave. Depression-anxiety was defined as a cut-off of 20 or higher on the Patient Health Questionnaire-Anxiety Depression Scale (PHQ-ADS). Of 1138 participants, 71.0% were female, 69.0% Arabs, 70.0% Non-Qataris, and 77.0% were < 40 years (the median age in Qatar is 32 years). In a fully-adjusted model, six variables were significantly associated with moderate-to-severe levels of depression or anxiety on the PHQ-ADS; Arab ethnicity (OR = 1.67, p = 0.026), never married versus married (OR = 1.69, p = 0.015), prior history of psychiatric disorder versus no history (OR = 1.80, p = 0.009), increased worries due to social media use for COVID-related news/updates (OR = 1.72, p = 0.003), a history of COVID-19 (OR = 1.76, p = 0.039), loneliness (OR = 1.91, p < 0.001), and lower levels of religiosity (OR = 0.96, p = 0.039). These associations also pertained in the reduced model, with the exception of religiosity which was only marginally statistically significant (OR = 0.97, p = 0.055). The potential risk factors identified may assist with anxiety and depression prevention in future COVID-19 waves, and similar national events, and assist with early intervention to treat sufferers
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