303 research outputs found
Comparing weight dynamics between urban and rural honey bee colonies in Latvia
Received: January 16th, 2023 ; Accepted: April 8th, 2023 ; Published: April 17th, 2023 ; Correspondence: [email protected] is an important agricultural industry in Latvia, which has an area of
64,589 km2 and is largely mixed forest. The natural foraging base does not provide the honey
yield evenly throughout the whole season, thus the average honey yield in Latvia is about 20 kg
per colony. The objective of this research was to compare the weight dynamics of colonies placed
in rural and urban environments. As urban beekeeping is becoming more popular, it is important
to understand whether there are enough foraging resources within the city for the bee colonies.
To do this, the weight changes of ten honey bee colonies was remotely monitored and analysed
during the summer period. Five colonies were located in the rural environment in Vecauce and
five in the urban environment in Jelgava city. Colonies were assessed using the precision
beekeeping approach and developed scale systems. It was concluded that for rural colonies in
Vecauce, the main weight increase occurred in June - from 41.02 to 54.68 kg - which resulted in
94% of the total increase for the summer period. Data analysis from the urban apiary revealed
that colonies increase weight during the entire monitoring period, indicating that there are
foraging resources available throughout the summer period within the city
Evaluation of the honey bee colonies weight gain during the intensive foraging period
Received: March 5th, 2022 ; Accepted: April 1st, 2022 ; Published: April 13th, 2022 ; Correspondence: [email protected] in Latvia has a long tradition and it is a classical branch of agriculture. In
Latvia, there is no traditional beekeeping region, and beekeeping is performed in all regions.
Honey yield is influenced by various factors - variety of crops (nectar plants) around the apiary,
man-made changes in land/forests (deforestation), climate change, beekeepersâ actions, etc.
Application of information and communication technologies (ICT) in the field of beekeeping can
bring benefits to the beekeepers. To be more specific, continuous remote monitoring of certain
bee colony parameters can improve beekeeperâs apiary management, by informing timely about
the nectar flow (or even provide information on bee colony states, e.g., swarming). In such a way,
beekeepers can plan their next actions - prepare supers or even choose to move the apiary to a
different geographical location. Within this research, weight gain of the ten honey bee colonies
was remotely monitored and analysed during two-week period at the beginning of the summer
2021 in Vecauce, Latvia, using the precision beekeeping approach. This monitoring period
corresponded to intensive flowering of the winter rapeseed and field beans. Colonies were
equipped with the automatic scales. In addition, colony and environmental temperature was
monitored. Measurements were taken every thirty minutes. Analysing the obtained data, weight
increase can be observed in all colonies, from 17 to 48 kg. As well, based on weight data,
swarming event can be identified. Constant monitoring of weight change can also help to identify
daily patterns in honey bee activity
Focusing of a tabletop soft-x-ray laser beam and laser ablation
Includes bibliographical references (page 1716).We focused the beam of a high-repetition-rate capillary-discharge tabletop laser operating at a wavelength of 46.9 nm, using a spherical Si/Sc multilayer mirror. The energy densities significantly exceeded the thresholds for the ablation of metals. Single-shot laser ablation patterns were used in combination with ray-tracing computations to characterize the focused beam. The radiation intensity within the 2-ÎŒm-diameter central region of the focal spot was estimated to be â1011 W/cm2, with a corresponding energy density of ~100 J/cm2
What happens to peat during bog fires? Thermal transformation processes of peat organic matter
Bog fires are a serious natural phenomena. Major increase in the number of fires has
happened during the last decades due to bog transformation into agricultural lands, accidents and
human activities. During bog fires the peat is exposed to high temperatures due to which chemical
transformation and even mineralisation of peat can occur. The aim of the study was to analyse
the impacts of the bog fires on the bog as an ecosystem, advance the understanding and
knowledge of fire impact on peat and humic matter properties and application possibilities. As
the material for the study peat samples from burnt sites and thermally treated peat were used. To
reveal peat transformation during bog fires, thermogravimetric analysis of peat samples were
done, where amounts of bitumens, humic acids and mineral matter were estimated. During bog
fires thermal modification of peat properties takes place, resulting in full mineralisation of peat
and release of mineral substances. Bog fires lead to development of peat char, bitumens and
significant changes in structure and properties of peat humic acids. However, from perspective
of application of peat as a substrate and from perspective of impacts on the bog ecosystems, the
effects are negligible
Medical Student Motivation to Work in E-learning
Nowadays information technology is widley used in studying process thus enabling students to acquire knowledge in a convenient place and time. It is a novel approach and a challenge for both â the students and the faculty of Latvian University Riga Medical College (LU RMK). In order to provide and develope e-learning environment LU RMK has launched a Project whose main objective is âto develop guidelines and video training materials in the e-environment for students and faculty staff in order to provide a more efficient studying processâ. Implementation of the project has been started with a pilot study âMedical studentsâ motivation to work in e-environmentâ, designed to explore studentsâ motivation and factors affecting the work of the e environment. Methods: A pilot study using a quantitative method â a survey. To achieve the goal 209 students have been surveyed in the LU RMK
Development of gaze aversion as disengagement from visual information
Older children, but not younger children, were found to look away more from the face of an interlocutor when answering difficult as opposed to easy questions. Similar results were found in earlier work with adults, who often avert their gaze during cognitively difficult tasks (A.M. Glenberg, J.L. Schroeder, & D.A. Robertson, 1998). Twenty-five 8-year-olds and 26 5-year-olds answered verbal reasoning and arithmetic questions of varying difficulty. The older children increased gaze aversion from the face of the adult questioner in response to both difficult verbal reasoning questions and difficult arithmetic questions. In contrast, younger children (5-year-olds) responded less consistently to cognitive difficulty. It is concluded that adultlike patterns of gaze aversion in response to cognitive difficulty are certainly acquired by 8 years of age. The implications of appropriate gaze aversion for childrenâs management of cognitive resources are considered
Applications of high repetition rate tabletop soft X-ray lasers become a reality in several fields
Includes bibliographical references (page 468).For many years researchers have envisioned the development of compact high repetition rate tabletop soft x-ray laser, that could be routinely used in application in numerous disciplines. With demonstrated average powers of several mW and millijoule-level pulse energy at 46.9nm, the Ne-like Ar capillary discharge-pumped laser is the first compact laser to reach this goal. In this paper we summarize the development status of high repetition rate tabletop soft x-ray lasers based on capillary discharge excitation, and give examples of their successful use in several applications. Results of the use of a caprllary discharge pumped 46.9nm laser m dense plasma interferometry, soft x-ray reflectometry for the determination of optical constants, characterization of diffraction gratings, laser ablation of materials, and plasma generation are described. The observation of lasing at 52.9nm line in Ne-like Cl with output pulse energy up to 10 ÎŒJ is also reported
Cognitive demands of face monitoring: Evidence for visuospatial overload
Young children perform difficult communication tasks better face to face than when they cannot see one another (e.g., Doherty-Sneddon & Kent, 1996). However, in recent studies, it was found that children aged 6 and 10 years, describing abstract shapes, showed evidence of face-to-face interference rather than facilitation. For some communication tasks, access to visual signals (such as facial expression and eye gaze) may hinder rather than help childrenâs communication. In new research we have pursued this interference effect. Five studies are described with adults and 10- and 6-year-old participants. It was found that looking at a face interfered with childrenâs abilities to listen to descriptions of abstract shapes. Children also performed visuospatial memory tasks worse when they looked at someoneâs face prior to responding than when they looked at a visuospatial pattern or at the floor. It was concluded that performance on certain tasks was hindered by monitoring another personâs face. It is suggested that processing of visual communication signals shares certain processing resources with the processing of other visuospatial information
Efficacy assessment of sustained intraperitoneal paclitaxel therapy in a murine model of ovarian cancer using bioluminescent imaging
We evaluated the pre-clinical efficacy of a novel intraperitoneal (i.p.) sustained-release paclitaxel formulation (PTXePC) using bioluminescent imaging (BLI) in the treatment of ovarian cancer. Human ovarian carcinoma cells stably expressing the firefly luciferase gene (SKOV3Luc) were injected i.p. into SCID mice. Tumour growth was evaluated during sustained or intermittent courses of i.p. treatment with paclitaxel (PTX). In vitro bioluminescence strongly correlated with cell survival and cytotoxicity. Bioluminescent imaging detected tumours before their macroscopic appearance and strongly correlated with tumour weight and survival. As compared with intermittent therapy with TaxolÂź, sustained PTXePC therapy resulted in significant reduction of tumour proliferation, weight and BLI signal intensity, enhanced apoptosis and increased survival times. Our results demonstrate that BLI is a useful tool in the pre-clinical evaluation of therapeutic interventions for ovarian cancer. Moreover, these results provide evidence of enhanced therapeutic efficacy with the sustained PTXePC implant system, which could potentially translate into successful clinical outcomes
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