DBSnap 2: New Features to Construct Database Queries by Snapping Blocks

Block-based environments for creating computer programs have become very useful learning tools in computer science as they enable focusing on the logic of a program rather than on its syntactical details. While most block-based environments support conventional (imperative) instructions, a few tools have been proposed to create database queries. One of these tools is DBSnap, a highly dynamic and open-source tool to create database query trees by dragging and connecting visual blocks representing datasets and database operators. In this paper, we introduce DBSnap 2, an extension of DBSnap that provides a set of improvements to facilitate the creation of simple and complex queries. The improvements include the support of database views (a key database concept), saving and importing queries, inserting, updating, and deleting data, the creation of charts, and various visual improvements. The demonstration of DBSnap 2 will show how the new features simplify the creation of queries and enable the graphical visualization of query results

DBSnap-Eval: Identifying Database Query Construction Patterns

Learning to construct database queries can be a challenging task because students need to learn the specific query language syntax as well as properly understand the effect of each query operator and how multiple operators interact in a query. While some previous studies have looked into the types of database query errors students make and how the availability of expected query results can help to increase the success rate, there is very little that is known regarding the patterns that emerge while students are constructing a query. To be able to look into the process of constructing a query, in this paper we introduce DBSnap-Eval, a tool that supports tree-based queries (similar to SQL query plans) and a block-based querying interface to help separate the syntax and semantics of a query. DBSnap-Eval closely monitors the actions students take to construct a query such as adding a dataset or connecting a dataset with an operator. This paper presents an initial set of results about database query construction patterns using DBSnap-Eval. Particularly, it reports identified patterns in the process students follow to answer common database queries

Asthma and gender impact accumulation of T cell subtypes

<p>Abstract</p> <p>Background</p> <p>The "Th2 hypothesis for asthma" asserts that an increased ratio of Th2:Th1 cytokine production plays an important pathogenic role in asthma. Although widely embraced, the hypothesis has been challenged by various empirical observations and has been described as overly simplistic. We sought to establish whether CD3+CD28-mediated and antigen-independent accumulation of type 1 and type 2 T cells differs significantly between nonasthmatic and asthmatic populations.</p> <p>Methods</p> <p>An ex vivo system was used to characterize the regulation of IFN-γ-producing (type 1) and IL-13-producing (type 2) T cell accumulation in response to CD3+CD28 and IL-2 stimulation by flow cytometry.</p> <p>Results</p> <p>IL-13-producing T cells increased in greater numbers in response to antigen-independent stimulation in peripheral blood lymphocytes from female atopic asthmatic subjects compared with male asthmatics and both male and female atopic non-asthmatic subjects. IFN-γ⁺T cells increased in greater numbers in response to either antigen-independent or CD3+CD28-mediated stimulation in peripheral blood lymphocytes from atopic asthmatic subjects compared to non-asthmatic subjects, regardless of gender.</p> <p>Conclusions</p> <p>We demonstrate that T cells from asthmatics are programmed for increased accumulation of both type 2 and type 1 T cells. Gender had a profound effect on the regulation of type 2 T cells, thus providing a mechanism for the higher frequency of adult asthma in females.</p

Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high-NO_x conditions

We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NO_x conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.2. The first-generation yield of glyoxal from isoprene was determined to be 2.1 (±0.6)%. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 hydroxycarbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NO_x conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 hydroxycarbonyls is important for models that include the production of the small organic molecules from isoprene

Analysis of photochemical and dark glyoxal uptake: Implications for SOA formation

The dependence of glyoxal uptake onto deliquesced ammonium sulfate seed aerosol was studied under photochemical (light + hydroxyl radical (OH)) and dark conditions. In this study, the chemical composition of aerosol formed from glyoxal is identical in the presence or absence of OH. In addition, there was no observed OH dependence on either glyoxal uptake or glyoxal-driven aerosol growth for this study. These findings demonstrate that, for the system used here, glyoxal uptake is not affected by the presence of OH. In combination with previous studies, this shows that the exact nature of the type of seed aerosol, in particular the presence of a coating, has a large influence on fast photochemical uptake of glyoxal. Due to the challenge of relating this seed aerosol dependence to ambient conditions, this work highlights the resulting difficulty in quantitatively including SOA formation from glyoxal in models

α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO_x environments

The gas-phase oxidation of α-pinene produces a large amount of secondary organic aerosol (SOA) in the atmosphere. A number of carboxylic acids, organosulfates and nitrooxy organosulfates associated with α-pinene have been found in field samples and some are used as tracers of α-pinene oxidation. α-pinene reacts readily with OH and O_3 in the atmosphere followed by reactions with both HO_2 and NO. Due to the large number of potential reaction pathways, it can be difficult to determine what conditions lead to SOA. To better understand the SOA yield and chemical composition from low- and high-NO_x OH oxidation of α-pinene, studies were conducted in the Caltech atmospheric chamber under controlled chemical conditions. Experiments used low O_3 concentrations to ensure that OH was the main oxidant and low α-pinene concentrations such that the peroxy radical (RO_2) reacted primarily with either HO_2 under low-NO_x conditions or NO under high-NO_x conditions. SOA yield was suppressed under conditions of high-NO_x. SOA yield under high-NO_x conditions was greater when ammonium sulfate/sulfuric acid seed particles (highly acidic) were present prior to the onset of growth than when ammonium sulfate seed particles (mildly acidic) were present; this dependence was not observed under low-NO_x conditions. When aerosol seed particles were introduced after OH oxidation, allowing for later generation species to be exposed to fresh inorganic seed particles, a number of low-NO_x products partitioned to the highly acidic aerosol. This indicates that the effect of seed acidity and SOA yield might be under-estimated in traditional experiments where aerosol seed particles are introduced prior to oxidation. We also identify the presence of a number of carboxylic acids that are used as tracer compounds of α-pinene oxidation in the field as well as the formation of organosulfates and nitrooxy organosulfates. A number of the carboxylic acids were observed under all conditions, however, pinic and pinonic acid were only observed under low-NO_x conditions. Evidence is provided for particle-phase sulfate esterification of multi-functional alcohols

Spatial pattern of ecosystems of birch-aspen small woods in Samara river basin

Охарактеризовано горизонтальну структуру нижніх ярусів березово-осикових колків Присамар’я Дніпровського з використанням комбінованого методу блоків і головних компонент. Статистично достовірно визначені багатовидові мозаїки для різних масштабів – мікро зональні, парцелярні та ценотичні.Охарактеризованы горизонтальную структуру нижних ярусов березово-осиновых колки Присамарья Днепровского с использованием комбинированного метода блоков и главных компонент. Статистически достоверно определены многовидовые мозаики для различных масштабов - микро зональные, парцеллярные и ценотические.The spatial pattern of herbage and underwood in birch-aspen small woods of Samara River basin has been estimated by combined method of blocks and main components. The significant multi-species spatial mosaics have been determined upon different scales: micro-zone, parcel and coenotic levels

Аналіз рослинності колкових лісових екосистем північного степу України

Conducted analysis of forest vegetation has allowed selecting and specifying classification and typological units of the aspen-and-birch separated small woods, which have statistically significant difference of ecotopic and coenotic parameters. Those parameters of studied forest ecosystems are characterised. Existence of the lines of hygrogenic and edaphogenic substitution, and succession rows are described. Phytoindication description of ecological factors’ pivotal conditions is presented. Driving factors determining parameters, structure and composition of the aspen-and-birch forest ecosystems are diminishing soil moisture, increasing annual temperatures amplitude and soil acidity. Проведенный анализ растительности колковых лесных экосистем позволил выделить и уточнить их классификационные и типологические единицы, которые статистически значимо дифференцируются по экотопическим и ценотическим параметрам. Охарактеризованы экотопические и ценотические параметры колковых лесных экосистем, для которых обосновано наличие рядов гигрогенного и эдафогенного замещения и сукцессионных рядов. Приведена фитоиндикационная характеристика ведущих режимов экологических факторов. Ведущими факторами, определяющими характеристики, структуру и сложение колковых лесных экосистем, являются уменьшение почвенного увлажнения, рост амплитуды годовых температур и кислотность почв.Проведений аналіз рослинності колкових лісових екосистем дозволив виділити та уточнити їх класифікаційні та типологічні одиниці, які статистично значимо диференціюються за екотопічними та ценотичними параметрами. Охарактеризовано екотопічні та ценотичні параметри колкових лісових екосистем, для яких обґрунтована наявність рядів гігрогенного та едафогенного заміщення та сукцесійних рядів. Наведено фітоіндикаційну характеристику провідних режимів екологічних факторів. Провідні фактори, що визначають характеристики, структуру та склад колкових лісових екосистем, – зменшення ґрунтового зволоження, зростання амплітуди річних температур і кислотність ґрунтів.

Edaphic regimes of intrazonal forest ecosystems of small rivers’ terraces of the northern part of Steppe zone of Ukraine

Наведено матеріали фітоіндикаційної оцінки природних і антропогенно трансформованих колкових екосистем. Визначено показники ґрунтового зволоження, сольового, кислотного та азотного режиму, вмісту гумусу для різних типів колків. Встановлено ряди гігрогенного та трофогенного заміщення для інтразональних колкових екосистем залежно від умов формування. Приведены материалы фитоиндикацийнои оценки природных и антропогенно трансформированных колочных экосистем. Определены показатели почвенного увлажнения, солевого, кислотного и азотного режима, содержания гумуса для разных типов Колка. Установлено ряды гигрогенного и трофогенного замещения для интразональных колочных экосистем в зависимости от условий формирования.Results on phytoindication research of native and anthropogenically transformed small insular aspen-birch woods (koloks) are under consideration. Parameters of the ground moisture, saline, acidity and nitrogen regimes, humus content for different types of koloks are presented. The directions of hydrogenic and trophogenic changes for intrazonal ecosystems in dependence of forming condition are given

Role of aldehyde chemistry and NO_x concentrations in secondary organic aerosol formation

Aldehydes are an important class of products from atmospheric oxidation of hydrocarbons. Isoprene (2-methyl-1,3-butadiene), the most abundantly emitted atmospheric non-methane hydrocarbon, produces a significant amount of secondary organic aerosol (SOA) via methacrolein (a C_4-unsaturated aldehyde) under urban high-NO_x conditions. Previously, we have identified peroxy methacryloyl nitrate (MPAN) as the important intermediate to isoprene and methacrolein SOA in this NO_x regime. Here we show that as a result of this chemistry, NO_2 enhances SOA formation from methacrolein and two other α, β-unsaturated aldehydes, specifically acrolein and crotonaldehyde, a NO_x effect on SOA formation previously unrecognized. Oligoesters of dihydroxycarboxylic acids and hydroxynitrooxycarboxylic acids are observed to increase with increasing NO_2/NO ratio, and previous characterizations are confirmed by both online and offline high-resolution mass spectrometry techniques. Molecular structure also determines the amount of SOA formation, as the SOA mass yields are the highest for aldehydes that are α, β-unsaturated and contain an additional methyl group on the α-carbon. Aerosol formation from 2-methyl-3-buten-2-ol (MBO232) is insignificant, even under high-NO_2 conditions, as PAN (peroxy acyl nitrate, RC(O)OONO_2) formation is structurally unfavorable. At atmospherically relevant NO_2/NO ratios (3–8), the SOA yields from isoprene high-NO_x photooxidation are 3 times greater than previously measured at lower NO_2/NO ratios. At sufficiently high NO_2 concentrations, in systems of α, β-unsaturated aldehydes, SOA formation from subsequent oxidation of products from acyl peroxyl radicals+NO_2 can exceed that from RO_2+HO_2 reactions under the same inorganic seed conditions, making RO_2+NO_2 an important channel for SOA formation