Different W cluster deposition regimes in pulsed laser ablation observed by in situ Scanning Tunneling Microscopy

We report on how different cluster deposition regimes can be obtained and observed by in situ Scanning Tunneling Microscopy (STM) by exploiting deposition parameters in a pulsed laser deposition (PLD) process. Tungsten clusters were produced by nanosecond Pulsed Laser Ablation in Ar atmosphere at different pressures and deposited on Au(111) and HOPG surfaces. Deposition regimes including cluster deposition-diffusion-aggregation (DDA), cluster melting and coalescence and cluster implantation were observed, depending on background gas pressure and target-to-substrate distance which influence the kinetic energy of the ablated species. These parameters can thus be easily employed for surface modification by cluster bombardment, deposition of supported clusters and growth of films with different morphologies. The variation in cluster mobility on different substrates and its influence on aggregation and growth mechanisms has also been investigated.Comment: 12 pages (3 figures); Surface Science (accepted

Strategies of the honeybee Apis mellifera during visual search for vertical targets presented at various heights: a role for spatial attention?

When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can use alternative search mechanisms such as spatial attention, which allows flexible focusing on different areas of the visual field. We asked individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the test phase, but bees increased their search performance significantly after a few learning trials: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target's position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target's appearance and adapt their search strategy accordingly. Different possible mechanisms of this behavioural adaptation are discussed.L.M. was recipient of a DOC-fFORTE fellowship of the Austrian Academy of Science at the Department of Integrative Zoology, University of Vienna. L.C. is supported by an ERC Advanced Grant and a Royal Society Wolfson Research Merit Award

Bumblebees Use Sequential Scanning of Countable Items in Visual Patterns to Solve Numerosity Tasks.

Most research in comparative cognition focuses on measuring if animals manage certain tasks; fewer studies explore how animals might solve them. We investigated bumblebees' scanning strategies in a numerosity task, distinguishing patterns with two items from four and one from three, and subsequently transferring numerical information to novel numbers, shapes, and colors. Video analyses of flight paths indicate that bees do not determine the number of items by using a rapid assessment of number (as mammals do in "subitizing"); instead, they rely on sequential enumeration even when items are presented simultaneously and in small quantities. This process, equivalent to the motor tagging ("pointing") found for large number tasks in some primates, results in longer scanning times for patterns containing larger numbers of items. Bees used a highly accurate working memory, remembering which items have already been scanned, resulting in fewer than 1% of re-inspections of items before making a decision. Our results indicate that the small brain of bees, with less parallel processing capacity than mammals, might constrain them to use sequential pattern evaluation even for low quantities

A novel approach to the synthesis of photoluminescent germanium nanoparticles by reactive laser ablation

NRC publication: Ye

The hoard of the Early Iron Age at the settlement of Dianovo-II (Belozersk district of the Kurgan region)

In 2016, in the area of Dianovo village of the Belozersk district of the Kurgan region (West Siberia), a hoard of the Early Iron Age artifacts was found. While examining the area for the identification of structures of the Civil War period, a round-bottomed vessel was accidentally discovered. Inside the container, there was a massive rectangular bronze plate, glass beads, and fragments of jewelry, including bronze strings, bronze plaques in the shape of fish and four-petal plaques strung on leather cords, all wrapped in organic material (felt?). In total, the Dianovo treasure contains 370 objects made of bronze and glass, assembled within a single set, classified as women’s. At present, this is one of very few elements of the women’s costume of the Early Iron Age that have been best preserved in the Southern Trans-Urals. These finds were transferred to the archaeological laboratory of the Kurgan State University, and later the archaeological survey was carried out at the discovery location by I.A. Spiridonov. The purpose of this research is a typological description of the contents of the hoard, its chronological analysis, and a possible reconstruction of the bronze ornament. The main research materials are the container in which the treasure was found — a ceramic round-bottomed vessel, a set of bronze objects that piece together a female (breast?) adornment, a set of glass beads of three types (rounded blue, black (square and rounded) with festoon-like white and yellow pattern), and a massive bronze plate with traces of manufacturing, which probably had the purpose of an ingot. Based on the analysis of the materials, it has been established that the hoard was most likely left by the population of the Gorokhovskaya Culture. This conclusion was made on the basis of the shape and features of the ceramic vessel. This is also supported by the location of the treasure and the general dating of individual items: glass beads of the Black Sea origin have numerous similarities in the sites and are quite clearly dated by these analogues to the 4th–3rd c. BC. The dating of other items of the hoard — elements of the bronze ornament and a bronze ingot-plate is complicated due to the lack of clearly dated analogues or chronological duration of their use. Judging by the composition and carefulness of packing of the items, this hoard apparently was of a situational (possibly in the event of an attack) and returnable character. © 2023 Russian Federation. All rights reserved.Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ-2023-0018Funding. Research is supported by the within the framework of the State task of the Ministry of Science and Higher Education of the Russian Federation FEUZ-2023-0018

Synthesis and characterization of group IV nanocrystals

The first reports that nanostructured silicon emits radiation in the visible wavelength date back twenty years. This observation is interesting from a fundamental point of view and is potentially important for device engineering, as it points to the opportunity of combining microelectronics and optoelectronics on the same silicon chip. This combination is becoming increasingly attractive due to the intrinsic limitations that are being met by the microelectronics industry in its attempt to progressively reduce device features. In this review, we describe and compare the structure and properties of group IV nanocrystals (mostly silicon, with some references to germanium) grown by ion implantation and reactive pulsed laser deposition. Particular emphasis is placed on structural and spectroscopic characterization, as well as size-dependent optical properties. The origin of the luminescence signal and the role of defects and interfaces are discussed in detail.</p

Organization of olfactory centres in the malaria mosquito Anopheles gambiae

Mosquitoes are vectors for multiple infectious human diseases and use a variety of sensory cues (olfactory, temperature, humidity and visual) to locate a human host. A comprehensive understanding of the circuitry underlying sensory signalling in the mosquito brain is lacking. Here we used the Q-system of binary gene expression to develop transgenic lines of Anopheles gambiae in which olfactory receptor neurons expressing the odorant receptor co-receptor (Orco) gene are labelled with GFP. These neurons project from the antennae and maxillary palps to the antennal lobe (AL) and from the labella on the proboscis to the suboesophageal zone (SEZ), suggesting integration of olfactory and gustatory signals occurs in this brain region. We present detailed anatomical maps of olfactory innervations in the AL and the SEZ, identifying glomeruli that may respond to human body odours or carbon dioxide. Our results pave the way for anatomical and functional neurogenetic studies of sensory processing in mosquitoes