Current estimation of the derivative of a nonstationary process based on a recurrent smoothing spline

A method of real-time reconstruction of the useful signal and its lower derivatives on the basis of a recurrent smoothing spline is presented. A calculation technique for a spline with the number of measurements at each segment greater than the number of nodes is given, and the spline coefficients are found by the variational approach

Development of the Keystroke Dynamics Recognition System

The paper is related to creating an algorithm for keystroke dynamics recognition and development of software, which is able to identify users according to their keystroke dynamics. Different characteristics of keystroke dynamics are considered. Probabilistic-statistical methods are compared with neural network algorithms for recognition. The algorithm for recognition was created and implemented. The software was tested with the help of some users. Their keystroke dynamics was analyzed in order to determine an efficiency of the created algorithm

Growth, toxicity and oxidative stress of a cultured cyanobacterium (Dolichospermum sp.) under different CO2/pH and temperature conditions

Peer reviewe

Ultrafast luminescence of Ga- and In-doped ZnO ceramics

The work of authors (a-c) was financially supported by Russian Foundation for Basic Research (RFBR, Russia) and the work of the last author (d) had financial support from State Education Development Agency (VIAA, Latvia) . All of that was approved as a result of ERA.Net RUS PLUS 2017 joint call for proposals. Here is the link for the joint call for reference: https://www.eranet-rus.eu/en/196.php .In the presented work we compare luminescence characteristics of ZnO:Ga and ZnO:In ceramics prepared by hot uniaxial pressing method. Two types of initial powders were used. The first one was nanosized powder prepared by precipitation method. In the second case we used microsized powders and mechanical admixturing the oxides of intended dopant. In both cases doping by the trivalent ions lead to a significant quenching of ZnO visible emission and an increase in near-band-edge luminescence. The study has shown that the type of dopant greatly affects the transmittance of ceramics prepared from nano- and micro sized powders. Several reasons for the specific effect of powder preparation process and a type of introduced dopant, including changes in dopant solubility, their interaction with the grain boundaries, etc., were considered. © 2021 The Author(s). Published under the CC-BY-NC-ND license.Russian Foundation for Basic Research (RFBR, Russia); State Education Development Agency (VIAA, Latvia); ERA.Net RUS PLUS 2017 joint call for proposals; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

How copepods can eat toxins without getting sick - gut bacteria help zooplankton to feed in cyanobacteria blooms

Toxin-producing cyanobacteria can be harmful to aquatic biota, although some grazers utilize them with often beneficial effects on their growth and reproduction. It is commonly assumed that gut microbiota facilitates host adaptation to the diet; however, the evidence for adaptation mechanisms is scarce. Here, we investigated the abundance of mlrA genes in the gut of the Baltic copepods Acartia bifilosa and Eurytemora affinis during cyanobacteria bloom season (August) and outside it (February). The mlrA genes are unique to microcystin and nodularin degraders, thus indicating the capacity to break down these toxins by the microbiota. The mlrA genes were expressed in the copepod gut year-round, being >10-fold higher in the summer than in the winter populations. Moreover, they were significantly more abundant in Eurytemora than Acartia. To understand the ecological implications of this variability, we conducted feeding experiments using summer- and winter-collected copepods to examine if/how the mlrA abundance in the microbiota affect: (1) uptake of toxic Nodularia spumigena, (2) uptake of a non-toxic algal food offered in mixtures with N. spumigena, and (3) concomitant growth potential in the copepods. The findings provide empirical evidence that the occurrence of mlrA genes in the copepod microbiome facilitates nutrient uptake and growth when feeding on phytoplankton mixtures containing nodularin-producing cyanobacteria; thus, providing an adaptation mechanism to the cyanobacteria blooms

COLD CASE INVESTIGATIONS WITHIN FAIRFAX COUNTY: TURNING THE LIABILITY OF TIME INTO AN ASSET

No department or individual involved in the investigation of homicides is ever going to have a 100% closure rate. Therefore, many departments will be faced with a situation where another homicide happens before they are finished handling the previous one. How does one manage these open cases; how often are they reviewed; and who is responsible once the assigned detective is either transferred or leaves the unit or department? Someone has to be able to answer questions from the family, media and anyone else who might inquire about the case. Based on the number of unsolved homicide cases within Fairfax County, the concept of a “Cold Case Squad” was explored. During January 1995, the Fairfax County Police Department implemented a Cold Case Squad consisting of one supervisor, three veteran detectives, two auxiliary police officers and one cadet. The Cold Case detectives inherited approximately 75 unsolved homicides which occurred in Fairfax County, Virginia, from 1964 through December 31, 1994. More than half of the unsolved homicides (42) have occurred in the past nine years. The hypothesis for this thesis was: The formulation of a Cold Case Squad would measurably reduce the number of unresolved homicides within Fairfax County. The primary evaluation factor for the thesis was the Cold Case Squad’s “close-ability” rate. The thesis identified and evaluated nine solvability factors utilized by the Cold Case Squad Supervisor. The solvability factors are considered when prioritizing case investigation, assigning personnel to an investigation and suspending investigate efforts. One of the goals for utilizing solvability factors is to develop a clear profile of cases with the most potential for close-ability. The study population for this thesis is the 42 unsolved homicides which have occurred in Fairfax County, Virginia, between January 1, 1986, and December 31, 1994. Solvability factor work sheets were completed and computated for the study population. The hypothesis has been proven as there is a measurable reduction in the number of unsolved homicides. From the study population, two cases have been closed by arrest, one case closed by exceptional means and one case is pending approval from the Commonwealth Attorney’s Office to obtain arrest warrants. These four cases represent a 9.5% reduction of unsolved cases within the study population. A copy of this thesis was given to the Cold Case Squad Supervisor for review and application. It is hoped the research from this thesis will be applied to the Cold Case Squad so it will become more effective and continue to turn the liability of time into an asset

Heterogeneous ice nucleation ability of aerosol particles generated from Arctic sea surface microlayer and surface seawater samples at cirrus temperatures

Sea spray aerosol particles are a recognised type of ice-nucleating particles under mixed-phase cloud conditions. Entities that are responsible for the heterogeneous ice nucleation ability include intact or fragmented cells of marine microorganisms as well as organic matter released by cell exudation. Only a small fraction of sea spray aerosol is transported to the upper troposphere, but there are indications from mass-spectrometric analyses of the residuals of sublimated cirrus particles that sea salt could also contribute to heterogeneous ice nucleation under cirrus conditions. Experimental studies on the heterogeneous ice nucleation ability of sea spray aerosol particles and their proxies at temperatures below 235K are still scarce. In our article, we summarise previous measurements and present a new set of ice nucleation experiments at cirrus temperatures with particles generated from sea surface microlayer and surface seawater samples collected in three different regions of the Arctic and from a laboratory-grown diatom culture (Skeletonema marinoi). The particles were suspended in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud chamber and ice formation was induced by expansion cooling. We confirmed that under cirrus conditions, apart from the ice-nucleating entities mentioned above, also crystalline inorganic salt constituents can contribute to heterogeneous ice formation. This takes place at temperatures below 220 K, where we observed in all experiments a strong immersion freezing mode due to the only partially deliquesced inorganic salts. The inferred ice nucleation active surface site densities for this nucleation mode reached a maximum of about 5 x 10(10) m(-2) at an ice saturation ratio of 1.3. Much smaller densities in the range of 10(8)-10(9) m(-2) were observed at temperatures between 220 and 235 K, where the inorganic salts fully deliquesced and only the organic matter and/or algal cells and cell debris could contribute to heterogeneous ice formation. These values are 2 orders of magnitude smaller than those previously reported for particles generated from microlayer suspensions collected in temperate and subtropical zones. While this difference might simply underline the strong variability of the number of ice-nucleating entities in the sea surface microlayer across different geographical regions, we also discuss how instrumental parameters like the aerosolisation method and the ice nucleation measurement technique might affect the comparability of the results amongst different studies

Influence of Arctic Microlayers and Algal Cultures on Sea Spray Hygroscopicity and the Possible Implications for Mixed-Phase Clouds

As Arctic sea ice cover diminishes, sea spray aerosols (SSA) have a larger potential to be emitted into the Arctic atmosphere. Emitted SSA can contain organic material, but how it affects the ability of particles to act as cloud condensation nuclei (CCN) is still not well understood. Here we measure the CCN-derived hygroscopicity of three different types of aerosol particles: (1) Sea salt aerosols made from artificial seawater, (2) aerosol generated from artificial seawater spiked with diatom species cultured in the laboratory, and (3) aerosols made from samples of sea surface microlayer (SML) collected during field campaigns in the North Atlantic and Arctic Ocean. Samples are aerosolized using a sea spray simulation tank (plunging jet) or an atomizer. We show that SSA containing diatom and microlayer exhibit similar CCN activity to inorganic sea salt with a κ value of ∼1.0. Large-eddy simulation (LES) is then used to evaluate the general role of aerosol hygroscopicity in governing mixed-phase low-level cloud properties in the high Arctic. For accumulation mode aerosol, the simulated mixed-phase cloud properties do not depend strongly on κ, unless the values are lower than 0.4. For Aitken mode aerosol, the hygroscopicity is more important; the particles can sustain the cloud if the hygroscopicity is equal to or higher than 0.4, but not otherwise. The experimental and model results combined suggest that the internal mixing of biogenic organic components in SSA does not have a substantial impact on the cloud droplet activation process and the cloud lifetime in Arctic mixed-phase clouds