Data-oriented approach for synthetic network traffic generation

Abstract. A significant portion of dynamic websites, called web applications present dynamic information, which can be fetched from a backend pre-emptively or on-demand. For popular sites and applications, the increased volume of network calls and connectivity creates high performance requirements for the server side implementation. A failure to fulfill these requirements might lead to security vulnerabilities, high latency, logical malfunctions, and other issues. Identifying and quantifying performance weaknesses is not trivial. Even if measurements are collected, they might not originate from a stable environment which allows truthful comparison between software versions. Often application programming interface (API) performance issues are found by accident while using the software, but a few more automated methods to find the issues have been created as well, such as automated end to end API tests. In this diploma thesis, a case of web application software is studied with the goal of increasing its performance testing capability. A data-oriented approach to create synthetic network traffic for performance testing is prototyped. The approach consists of recording incoming network traffic at the server, finding user sequences within the traffic, which are then used to create a model of the users. The model can then be utilized to generate synthetic network requests, which have the same characteristics as real network traffic. The synthetic network requests are then used to generate load in a performance test environment. The approach is evaluated by its applicability for the use case.Datapohjainen lähestymistapa verkkoliikenteen syntetisointiin. Tiivistelmä. Suuri osa dynaamisista verkkosivuista eli verkkosovelluksista esittää käyttäjälle dynaamisesti tietoa. Tarvittava tieto haetaan tyypillisesti palvelimelta (jatkossa "backend"), jonne voidaan myös lähettää dataa. Suosituilla verkkosovelluksilla voi olla valtava määrä samanaikaisia käyttäjiä, mikä aiheuttaa suuren kuorman backendille. Mahdollinen suuri kuorma johtaa korkeisiin suorituskykyvaatimuksiin. Epäonnistuminen suorituskykyvaatimusten täyttämisessä voi johtaa tietoturvaongelmiin, pitkiin vasteaikoihin, loogisiin virheisiin tai muihin ongelmiin. Verkkopalvelun suorituskykyheikkousten löytäminen ja tunnistaminen ei ole triviaali tehtävä. Vaikka ohjelman suorituksesta kerättäisiin tietoa, se ei välttämättä pohjaudu vakaasta ja toistettavasta ympäristöstä mitatulle datalle. Usein backendien rajapintojen suorituskykyheikkoudet löytyvät vahingossa rajapintaa käytettäessä, mutta muutamia automatisoituja keinoja heikkousten löytämiseksi on olemassa. Tässä diplomityössä tutkitaan yhden verkkosovelluksen käyttäjien datapohjaista mallinnusta, ensisijaisena tavoitteena nostaa sovelluksen suorituskykytestauksen tasoa. Työssä kokeillaan datalähtöistä lähestymistapaa verkkoliikenteen mallintamiseksi ja syntetisoimiseksi. Lähestymistapa koostuu verkkoliikenteen nauhoittamisesta, käyttäjäsekvenssien tunnistamisesta verkkoliikenteen joukosta ja käyttäjien mallintamisesta. Mallinnettujen käyttäjien avulla voidaan luoda synteettistä verkkoliikennettä, joka muistuttaa ominaisuuksiltaan alkuperäistä nauhoitettua verkkoliikennettä. Synteettistä liikennettä käytetään suorituskykytestaukseen tarvittavan kuorman luomisessa. Lopulta lähestymistavan onnistumista ja sovellettavuutta arvioidaan

Carbon Dioxide emissions from an Acacia plantation on peatland in Sumatra, Indonesia

Peat surface CO2 emission, groundwater table depth and peat temperature were monitored for two years along transects in an Acacia plantation on thick tropical peat (>4 m) in Sumatra, Indonesia. A total of 2300 emission measurements were taken at 144 locations, over a 2 year period. The autotrophic root respiration component of CO2 emission was separated from heterotrophic emission caused by peat oxidation in three ways: (i) by comparing CO2 emissions within and beyond the tree rooting zone, (ii) by comparing CO2 emissions with and without peat trenching (i.e. cutting any roots remaining in the peat beyond the tree rooting zone), and (iii) by comparing CO2 emissions before and after Acacia tree harvesting. On average, the contribution of autotrophic respiration to daytime CO2 emission was 21% along transects in mature tree stands. At locations 0.5 m from trees this was up to 80% of the total emissions, but it was negligible at locations more than 1.3 m away. This means that CO2 emission measurements well away from trees were free of any autotrophic respiration contribution and thus represent only heterotrophic emissions. We found daytime mean annual CO2 emission from peat oxidation alone of 94 t ha−1 y−1 at a mean water table depth of 0.8 m, and a minimum emission value of 80 t ha−1 y−1 after correction for the effect of diurnal temperature fluctuations, which may result in a 14.5% reduction of the daytime emission. There is a positive correlation between mean long-term water table depth and peat oxidation CO2 emission. However, no such relation is found for instantaneous emission/water table depth within transects and it is clear that factors other than water table depth also affect peat oxidation and total CO2 emissions. The increase in the temperature of the surface peat due to plantation establishment may explain over 50% of peat oxidation emissions. Our study sets a standard for greenhouse gas flux studies from tropical peatlands under different forms of agricultural land management. It is the first to purposefully quantify heterotrophic CO2 emissions resulting from tropical peat decomposition by separating these from autotrophic emissions. It also provides the most scientifically- and statistically-rigorous study to date of CO2 emissions resulting from anthropogenic modification of this globally significant carbon rich ecosystem. Our findings indicate that past studies have underestimated emissions from peatland plantations, with important implications for the scale of greenhouse gas emissions arising from land use change, particularly in the light of current, rapid agricultural conversion of peatlands in the Southeast Asian region.Peer reviewe

Biomass production and feeding value of whole-crop cereal-legume-silages

In eastern Finland, several mixtures of spring wheat, spring barley, spring oats and/or rye with vetches and/or peas were evaluated in field experiments in 2005-2007 for their dry matter procuction, crude protein concentration and digestibility using three different harvesting times

Angiopoietin-like protein 3, an emerging cardiometabolic therapy target with systemic and cell-autonomous functions

Angiopoietin like protein 3 (ANGPTL3) is best known for its function as an inhibitor of lipoprotein and endothelial lipases. Due to the capacity of genetic or pharmacologic ANGPTL3 suppression to markedly reduce circulating lipoproteins, and the documented cardioprotection upon such suppression, ANGPTL3 has become an emerging therapy target for which both antibody and antisense oligonucleotide (ASO) therapeutics are being clinically tested. While the antibody is relatively selective for circulating ANGPTL3, the ASO also depletes the intra-hepatocellular protein, and there is emerging evidence for cell-autonomous functions of ANGPTL3 in the liver. These include regulation of hepatocyte glucose and fatty acid uptake, insulin sensitivity, LDL/VLDL remnant uptake, VLDL assembly/secretion, polyunsaturated fatty acid (PUFA) and PUFA-derived lipid mediator content, and gene expression. In this review we elaborate on (i) why ANGPTL3 is considered one of the most promising new cardiometabolic therapy targets, and (ii) the present evidences for its intra-hepatocellular or cell-autonomous functions.Peer reviewe

Subsidence and carbon loss in drained tropical peatlands

Biogeosciences931053-107

Current and future CO2 emissions from drained peatlands in Southeast Asia

Peer reviewe

High heterotrophic CO2 emissions from a Malaysian oil palm plantations during dry-season

Background Tropical peatlands are currently being rapidly cleared and drained for the establishment of oil palm plantations, which threatens their globally significant carbon sequestration capacity. Large-scale land conversion of tropical peatlands is important in the context of greenhouse gas emission factors and sustainable land management. At present, quantification of carbon dioxide losses from tropical peatlands is limited by our understanding of the relative contribution of heterotrophic and autotrophic respiration to net peat surface CO2 emissions. Methods In this study we separated heterotrophic and autotrophic components of peat CO2 losses from two oil palm plantations (one established in ‘2000’ and the other in 1978, then replanted in ‘2006’) using chamber-based emissions sampling along a transect from the rooting to non-rooting zones on a peatland in Selangor, Peninsular Malaysia over the course of three months (June-August, 2014). Collar CO2 measurements were compared with soil temperature and moisture at site and also accompanied by depth profiles assessing peat C and bulk density. Results The soil respiration decreased exponentially with distance from the palm trunks with the sharpest decline found for the plantation with the younger palms. The mean heterotrophic flux was 1244.7 ± SE 149.2 mg m-2h-1 and 663.8 ± SE 102.2 mg m-2h-1 at the 2000 and 2006 plantations, respectively. Autotrophic emissions adjacent to the palm trunks were 944 ± SE 99.7 mg m-2h-1 and 1962 ± SE 246 mg m-2h-1 at the 2000 and 2006 plantations, respectively. Heterotrophic CO2 flux was positively related to peat soil moisture, but not temperature. Total peat C stocks were 60 kg m-2 (down to 1 m depth) and did not vary among plantations of different ages but SOC concentrations declined significantly with depth at both plantations but the decline was sharper in the second generation 2006 plantation. Conclusions The CO2 flux values reported in this study suggest a potential for very high carbon (C) loss from drained tropical peats during the dry season. This is particularly concerning given that more intense dry periods related to climate change are predicted for SE Asia. Taken together, this study highlights the need for careful management of tropical peatlands, and the vulnerability of their carbon storage capability under conditions of drainage

Effects of a fibre-enriched milk drink on insulin and glucose levels in healthy subjects

<p>Abstract</p> <p>Background</p> <p>The glycaemic response to foods is dependent on the quality and content of carbohydrates. Carbohydrates in the form of dietary fibre have favourable effects on insulin and glucose metabolism and may help to control energy intake. Dairy products have a relatively low carbohydrate content, and most of the carbohydrate is in the form of lactose which causes gastrointestinal symptoms in part of the population. In order to avoid these symptoms, dairy products can be replaced with lactose-free dairy products which are on the market in many parts of the world. However, the effects of lactose-free products on insulin and glucose metabolism have not been studied.</p> <p>Methods</p> <p>In the present study, we investigated the effects of 1) a lactose-free milk drink, 2) a novel fibre-enriched, fat- and lactose-free milk drink and 3) normal fat-free milk on serum glucose and insulin levels and satiety using a randomized block design. Following an overnight fast, 26 healthy volunteers ingested 200 ml of one of these drinks on three non-consecutive days. Insulin and glucose levels and subjective satiety ratings were measured before the ingestion of the milk product and 20, 40, 60, 120 and 180 minutes after ingestion. The responses were calculated as the area under the curve subtracted by the baseline value (AUC minus baseline).</p> <p>Results</p> <p>The insulin response was significantly lower for the fibre-enriched milk drink than it was for the other milk products (AUC, <it>P </it>= 0.007). There were no differences in the response for glucose or in the AUC for the subjective satiety ratings between the studied milk products.</p> <p>Conclusion</p> <p>The present results suggest that this novel milk drink could have positive effects on insulin response.</p