The Circle Packing Theorem

Il teorema di Koebe-Andreev-Thurston concerne l'esistenza di impacchettamenti di cerchi con un dato grafo di contatto. In questo lavoro presentiamo una dimostrazione elementare di tale teorema, insieme a qualche esempio di applicazione. Descriveremo, nel terzo capitolo, la congettura di Thurston sull'approssimazione di mappe conformi tamite impacchettamenti di cerchi e daremo una dimostrazione del teorema del separatore planare basata sul teorema di Koebe-Andreev-Thurston

PEAK VERTICAL FLOOR ACCELERATIONS OF TALL STEEL STRUCTURES

To meet modern day challenges structural engineers must properly design not only the primary structural elements of buildings but increasingly the secondary elements too. Damage or failure of nonstructural components (NSCs) and their attachments can present large economic losses, impaired building services and functionality, as well as life safety and emergency egress concerns. To properly design these components, it is important to accurately estimate their maximum acceleration demands including horizontal and vertical components of acceleration. In an effort to better understand vertical acceleration demands of rigid NSCs in multistory buildings and assess the building code provisions a 20-story office building, that is representative of a typical structure, is designed. Vertical acceleration demands are characterized through the use of floor acceleration spectra which are obtained for various points on the plan floor by running elastic modal time histories using 106 recorded ground motions. The main findings of this study are that peak vertical floor acceleration (PVFA) demands vary in plan due to the out of plane flexibility of the floor. Points in the mid portions of the floor slab experience much higher accelerations than points at column locations. The vertical seismic force design provisions of ASCE 7-10 underestimates the PVFA in a majority of the points found in the floor plan at least 50% of the time. A comparison and discussion between these results and the findings of a recent study out of the University of Reno is provided

Effects of Microhabitat Selection on Feeding Rates of Net-Spinning Caddisfly Larvae

Net-spinning caddisfly larvae of the family Hydropsychidae are known to prefer microhabitats with large, stable substrate and high water flow velocity. It is often assumed that net spinners in high-velocity microhabitats have higher feeding or growth rates than larvae in less preferred sites, but there is no direct evidence to support this assumption. We hypothesized that net-spinning caddisflies would select microhabitats that offered the greatest feeding rates. This hypothesis was tested by field experiments in which we determined if net-spinning caddisfly larvae preferred high-velocity sites even when substrate size and type were held constant. We then measured feeding rates of net spinners in microhabitats with different flow characteristics. High-flow positions were selected by 96% of hydropsychid larvae colonizing artificial moss substrates. Artemia nauplii released into the water column were captured by individual larvae in high-flow sites at a rate of 0.016%/m, significantly higher than the capture rate in low-flow sites. Combining this rate of prey capture with mean hydropsychid densities of 1125 individuals/m2, we estimate that hydropsychid larvae in riffles remove drifting invertebrate prey at a rate of «18%/m. Assuming exponential prey removal, a prey item in the drift would travel an average of only 5.5 m before being consumed. This study is one of the first to show that the distribution of a stream filter feeder is related to the feeding rates obtainable in different microhabitats

A Tool for Describing and Checking Natural Semantics Definitions of Programming Languages

Many universities have courses and projects revolving around compiler or interpreter implementation as part of their degree programmes in computer science. In such teaching activities, tool support can be highly beneficial. While there are already several tools for assisting with development of the front end of compilers, tool support tapers off towards the back end, or requires more background experience than is expected of undergraduate students. Structural operational semantics is a useful and mathematically simple formalism for specifying the behaviour of programs and a specification lends itself well to implementation; in particular big-step or natural semantics is often a useful and simple approach. However, many students struggle with learning the notation and often come up with ill-defined and meaningless attempts at defining a structural operational semantics. A survey shows that students working on programming language projects feel that tool support is lacking and would be useful. Many of these problems encountered when developing a semantic definition are similar to problems encountered in programming, in particular ones that are essentially the result of type errors. We present a pedagogical metalanguage based on natural semantics, and its implementation, as an attempt to marry two notions: a syntax similar to textbook notation for natural semantics on the one hand, and automatic verification of some correctness properties on the other by means of a strong type discipline. The metalanguage and the tool provide the facilities for writing and executing specifications as a form of programming. The user can check that the specification is not meaningless as well as execute programs, if the specification makes sense.Comment: In Proceedings FROM 2022, arXiv:2209.0920

Optimasi Reaksi Konversi Selulosa Menjadi Asam Laktat Dengan Katalis Mg0,95Ni0,05F2

Pada penelitian ini katalis magnesium fluorida dengan di doping nikel disintesis dengan metode sol gel. Katalis dikarakterisasi dengan difraksi sinar-X, FTIR, adsorpsi piridin-FTIR dan adsorpsi N2. Hasil karakterisasi menunjukan bahwa proses doping Ni pada katalis MgF2 berjalan dengan baik dengan sisi asam Lewis dan Brønsted, SBET, dan volume pori masing-masing sebesar 0,117, 0,047, 12,97 m2/g dan 0,093 cm3/g. Uji kinerja katalis dilakukan pada reaksi konversi selulosa menjadi asam laktat dengan optimasi terhadap beberapa faktor yang berpengaruh terhadap reaksi yaitu suhu, waktu, massa katalis, dan volume HCl. Berdasarkan hasil optimasi dari faktor-faktor tersebut diperoleh kondisi optimum yaitu pada suhu 240 °C, waktu reaksi 3 jam, massa katalis 0,06 gram, dan volume HCl 0,03% sebesar 50 mL dengan yield asam laktat optimum sebesar 60,02%. ================================================================================================================================ In this study magnesium fluoride catalyst doped by nickel was synthesized by the sol gel method. The catalyst was characterized by X-ray diffraction, FTIR, pyridine-FTIR adsorption and N2 adsorption. Characterization results showed that the Ni doping process on the MgF2 catalyst worked well with Lewis and Brønsted acid sites, SBET, and pore volume values are 0.117, 0.047, 12.97 m2/g and 0.093 cm3/g. The catalyst performance has been test on the conversion of cellulose into lactic acid with the optimization of several factors that affect the reaction, namely temperature, time, catalyst mass, and volume of HCl. Based on the optimization results from these factors, the optimum conditions are obtained at a temperature of 240 °C, 3 hours of reaction time, 0.06 gram of catalyst mass , and a 50 mL volume of HCl 0.03% with an optimum lactic acid yield of 60,02%

Emotional or Affective Mental Processes, the Concept and Essence of Reduced Liability for Committing an Offense

In this paper we analyze the issue of reduced criminal liability of the active subject of the offense which is affected by a neuropsychological or mental disorder, because of which its discernment was altered in the moment of committing the offense, provided by law. We present a thorough scan of this issue. The article also highlights the non-unitary practice of the Romaniancriminal legislation with the European traditional criminal legislation

Cod Liver Oil as a Source of Vitamin A

In the course of experiments having for their object the study of the properties of vitamin A with a view to its isolation, certain observations were made concerning the behavior of animals on various rations containing cod liver oil. It was noted that different samples of cod liver oil apparently vary markedly in vitamin A potency. Xerophthalmia has been produced in rats on diets containing as much as 3 per cent of cod liver oil. Synthetic rations containing cod liver oil evolve a penetrating odor resembling acrolein. When the cod liver oil is replaced with butter fat, this odor is not observed. It is possible that the failure of rats on diets containing certain samples of cod liver oil may be due to one or more of the following factors. 1. A decreased consumption of the diet clue to this decomposition product. 2. A destruction of vitamin A which runs parallel with the destruction of the cod liver oil. 3. Certain samples of cod liver oil are not as rich in vitamin A as supposed heretofore

Structural controls on multistage gold mineralisation within the Baie Verte Peninsula of Newfoundland, Canada

The Baie Verte Peninsula (BVP) is one of the richest auriferous regions within the Newfoundland Appalachians hosting more than 100 economic and sub-economic gold occurrences. The geological setting of the BVP resulted from the accretion of several micro-terranes of Iapetus origin to the Laurentian margin during the Ordovician Taconic Orogeny. The Baie Verte Line (BVL), a major crustal fault, represents the suture between the Laurentian margin and the accreted island arcs. Subsequent progressive deformation (D2) developed under a sinistral transpressional setting during the Salinic and Acadian orogenic events. Later deformational phases (D3-D4) resulted in response to complex dextral transcurrent motions localised along the BVL during the Neo-Acadian Orogeny. The studied gold occurrences, Stog’er Tight, Argyle, Romeo & Juliet, Deer Cove, and Pine Cove lie along splays of the BVL. New structural, mineralogical, and geochronological data has been collected through geological mapping, optical and SEM/CL investigations of mineralized samples, and in-situ LA-ICP-MS U-Th-Pb geochronology of monazite, xenotime, and titanite. Structural data analysis showed that at least three deformational events (D2-D4) influenced the formation and the present geometry of the gold deposits. Mineralogical and geochronological data revealed complex paragenetic sequences in each deposit and at least two periods of gold precipitation. The age of the first gold mineralising moment is constrained between ~420 to 410 Ma. The mineralised veins formed during the D2 progressive deformation, under brittle-ductile conditions, broadly synchronous with the development of E-W striking and south directed thrusts, splays of BVL. The maximum age of the second gold mineralising event is ~396 Ma, whereas the best estimate age is ~380 Ma. The gold bearing veins formed during the D3-D4 deformational events. At this time the entire BVP was under extension-related exhumation processes. Currently, it is unclear whether the later mineralising fluids either augmented the existing gold endowment or remobilized the pre-existing gold