Do Individual Investors Consciously Speculate on Reversals? Evidence from Leveraged Warrant Trading

Using proprietary data on bank-issued knock-out warrants, we find that individual investors, on aggregate, bet on price reversals. In a simple model we demonstrate that a mechanical channel due to market and product characteristics may account for investors' betting on reversals, even if investors' purchasing and selling decisions are independent of past returns. Our empirical results suggest that the mechanical channel can explain almost one half of the associationbetween past returns and individual investors' order flow, while the rest can be attributed to the disposition effect, that is, investors' higher propensity to sell assets from their portfolios that have appreciated

Two-Step Concentration of Complex Water Samples for the Detection of Viruses

The accurate detection and quantification of pathogenic viruses in water is essential to understand and reduce the risk of human infection. This paper describes a two-step method suitable for concentrating viruses in water and wastewater samples. The method involves a tangential flow ultrafiltration step that reduces the sample volume of 1–10 L to approximately 50 mL, followed by secondary precipitation using polyethylene glycol 6000, which reduces the volume to 1–4 mL. For method validation, water samples were spiked with different concentrations of enteric viruses, and viral recovery in the concentrates exceeded 10% in all experiments. The method is suitable for water samples with high and low salinity and turbidity, allowing an accurate comparison of viral titers in a diverse range of water types. Furthermore, the method has the potential to concentrate other pathogens, e.g., bacteria or protozoa. Hence, the use of this method can improve the holistic assessment of risks associated with wastewater-contaminated environments

Evaluation of Molecular Methods for the Detection and Quantification of Pathogen-Derived Nucleic Acids in Sediment

The accurate detection of pathogens in environmental matrices, such as sediment, is critical in understanding pathogen fate and behavior in the environment. In this study, we assessed the usefulness of methods for the detection and quantification of Vibrio spp. and norovirus (NoV) nucleic acids in sediment. For bacteria, a commonly used direct method using hexadecyltrimethylammonium bromide (CTAB) and phenol-chloroform-isoamyl alcohol (PCI) extraction was optimized, whereas for NoV, direct and indirect (virus elution—concentration) methods were evaluated. For quantification, commercially available quantitative PCR (qPCR) and reverse transcription qPCR (RT-qPCR) kits were tested alongside a digital PCR (dPCR) approach. CTAB-based extraction combined with 16 h polyethylene glycol 6000 (PEG6000) precipitation was found to be suitable for the direct extraction of high abundance bacterial and viral nucleic acids. For the indirect extraction of viral RNA, beef extract-based elution followed by PEG6000 precipitation and extraction using the NucliSENS® MiniMag® Nucleic Acid Purification System and the PowerViral® Environmental RNA/DNA Isolation Kit and qRT-PCR resulted in 83–112 and 63–69% recoveries of NoV, respectively. dPCR resulted in lower viral recoveries (47 and 9%) and ~4 orders of magnitude lower Vibrio concentrations (3.6–4.6 log(10) gc/100 g sediment) than was observed using qPCR. The use of internal controls during viral quantification revealed that the RT step was more affected by inhibitors than the amplification. The methods described here are suitable for the enumeration of viral and/or bacterial pathogens in sediment, however the use of internal controls to assess efficiency is recommended

Ms Excel-alapú módszer célorientált mintavételi terv készítéséhez = Ms excel-based method for the preparation of target-oriented sampling plans

Az ellenőrző vizsgálatok eredményeinek reális értékeléséhez elengedhetetlen, hogy az a mintavétel a vizsgálat céljának megfelelően történjen. Az eredmények szokásos statisztikai módszerekkel történő kiértékelésének egyik előfeltétele a véletlen mintavétel, amely azt jelenti, hogy az előre meghatározott mintázandó sokaság (mintavételi keret) minden egyes tagja egyenlő valószínűséggel kerül kiválasztásra. A mintavételi keret, rétegzett mintavétel esetén, magában foglalhatja a vizsgálat tárgyát képező teljes sokaság egy részét. Egy réteget alkothatnak például a korábbi tapasztalatok alapján kiemelten kockázatosnak ítélt termelő egységek, a biotermékelőállítására szakosodott vállalkozások vagy az ország lakosságának egy bizonyos korosztályhoz tartozó csoportja. Tekintve, hogy minden kereskedelmi forgalomba kerülő tétel vizsgálata csak ritka esetben indokolt, illetve kivitelezhető, a termelési gyakorlat ellenőrzése véletlen mintavételen alapuló vizsgálati program alapján történik. Cikkünkben egy olyan MS Excel alapú, speciális feltételeket kielégítő, véletlen mintavételre alkalmas eljárást mutatunk be, amelyet tejminták aflatoxin M1 (AFM1) szennyezettségének ellenőrzésére dolgoztunk ki, azonban elvei - az adott körülményekhez adaptálva - más esetekben is alkalmazhatók. A kidolgozott eljárás egyik előnye, hogy jelentősen nagyobb számú mintavételi sorrend felállítását teszi lehetővé, mint a manuális módszerek. A művelet elvégzése minden olyan esetben segítséget nyújt, amikor állandó elemszámú mintavételi keretből, rendszeresen kell rögzített számú random mintát venni. Az eljárásmód például alkalmas lehet egy adott nyersanyag-beszállítói kör termelésének ellenőrzésére, legyen szó akár tejtermékek, bébiételek, vagy más gyümölcs-, illetve zöldségalapú termékek gyártásához felhasznált nyersanyagok szermaradék-tartalmának ellenőrzéséről, betakarításkor vagy közvetlenül azt megelőzően. A módszer másik fontos előnye, hogy lehetővé teszi a mintavételi körben szereplő egységek súlyozását is. Az eljárás hátterétadó-olasz partnerekkel közösen végzett-statisztikai elemzés [3] célja olyan mintavételi terv elkészítése volt, amely a környezeti hatások miatt bekövetkező AFM1 koncentráció növekedésének észlelését időben és költséghatékonyan (a lehető legkevesebb mintából, meghatározott statisztikai megbízhatósággal) teszi lehetővé. A mintavételi terv használatával - késedelem nélkül beavatkozva - megelőzhető a határértéket meghaladó AFM1 szennyezettségű, nagy mennyiségű tételek megsemmisítése, illetve forgalomba kerülése. For realistic evaluation of the results of control analyses, it is essential that it is performed in accordance with the purpose of the analysis. One of the prerequisites of the evaluation of the results using the usual statistical methods is random sampling, which means that each member of the predetermined population to be sampled (sampling frame) is chosen with the same probability. The sampling frame, in the case of stratified sampling, may include a subgroup of the whole population under investigation. A single stratum can consist of, for example, production units deemed high risk, based on previous experience, businesses specializing in the production of organic products, or a certain age group of a country’s population. Given that the analysis of all commercial lots is very rarely justified or feasible, inspection of production practice is performed on the basis of an analytical program based on random sampling. In this paper, an MS Excel-based procedure satisfying special conditions and suitable for random sampling is presented, which was developed for the inspection of the aflatoxin M1 (AFM1) contamination of milk samples, however, its principles - adapted to the given conditions - may be applied in other cases as well. One of the advantages of the procedure developed is that it enables the creation of sampling sequences with significantly higher numbers, than do manual methods. Performing the operation helps in all cases when a fixed number of random samples is taken regularly from a sampling frame of constant element number. For example, the procedure may be suitable for the monitoring of the production of a given group of raw material suppliers, whether it be the inspection of the pesticide residue content of raw materials used for the production of dairy products, baby food, or other fruit or vegetable-based products, during the harvest or immediately prior to it. Another important advantage of the method is that it enables the weighting of the units within the sampling range. The goal of the statistical analysis [3] providing the background for the procedure - which was carried out together with Italian partners - was to prepare a sampling plan that enables the detection of an increase in AFM1 concentrations due to environemental effects in a timely and cost-effective manner (with a minimum number of samples and a given statistical reliability). Using the sampling plan, and by intervening immediately, destruction of large lots with AFM1 contaminations exceeding the limit value, or their commercial distribution can be prevented

Viral dispersal in the coastal zone: A method to quantify water quality risk

Waterborne and shellfish-borne enteric viruses associated with wastewater-polluted coastal waters (e.g. Norovirus, Hepatitis A/E viruses, Adenovirus) represent a major threat to human health. Improved understanding of the locations and periods of heightened risks can help target mitigation measures and improve public health. We developed a river-estuary-coast model to simulate virus dispersal, driven by point source discharges and river flows in combination with tidal forcing. Viral inputs were based on measured wastewater adenovirus concentrations and the model was implemented with or without viral die-off. We applied the model to the Conwy river (North Wales, UK), through the estuary, to the Irish Sea coast where bathing waters and shellfisheries are known to be prone to viral contamination. Using a suite of scenarios, we showed that river flow was the primary control of viral export to the coast. Since the Conwy catchment is short and steep, and the estuary is small and river-dominated, short-duration high intensity ‘flash floods’ were shown to transport viruses through the estuary and out to sea, despite dilution or die-off effects. Duplicating flow events (i.e., storm clustering) did not double the virus export since the virus re-entered the estuary on the flood tide. The tidal magnitude and timing of high water relative to peak river flow were also important drivers regulating viral dispersal. A worst-case event simulation (i.e., combining high river flows with high viral loading and high spring tide) resulted in increased concentrations of virus at nearby coasts, although the spatial spread was similar to the previous scenarios. Our results suggest that impact models for predicting and mitigating episodes of poor microbiological water quality may require careful representation of the intensity and timings of river flow when evaluating pathogen exposure risk

Wastewater and public health: the potential of wastewater surveillance for monitoring COVID-19

Pathogenic viruses represent one of the greatest threats to human well-being. As evidenced by the COVID-19 global pandemic, however, halting the spread of highly contagious diseases is notoriously difficult. Successful control strategies therefore have to rely on effective surveillance. Here, we describe how monitoring wastewater from urban areas can be used to detect the arrival and subsequent decline of pathogens, such as SARS-CoV-2. As the amount of virus shed in faeces and urine varies largely from person to person, it is very difficult to quantitatively determine the number of people who are infected in the population. More research on the surveillance of viruses in wastewater using accurate and validated methods, as well as subsequent risk analysis and modelling is paramount in understanding the dynamics of viral outbreaks

Előtérben a háttér - Az önkéntesség Magyarországon (The background in the foreground – Volunteering in Hungary)

Az önkéntesség témája talán sosem lehetett olyan aktuális, mint 2011-ben, az Önkéntesség Európai Évében. Az e téma köré szerveződött rendezvények talán népszerűbbé tehették az önkéntességet Magyarországon is. Az embereket legjobban a sport szeretete ösztönzi önkéntességre, pl. egy nagy sportrendezvény megrendezésekor a szervezők nagyban támaszkodnak az önkéntes munkaerőre. Azonban fontos lenne, hogy más területeken is felismerjék az emberek az effajta munkavégzés előnyeit. ______ The issue of volunteering may never be so actual, as in 2011, the European Year of Volunteering. The events which are organized around this theme might make volunteering more popular in Hungary. People are mostly encouraged by sport love for volunteering for example when arranging a great sport event the organizers can rely largely on the volunteers. However it would be important that people recognize the benefits of this kind of work in other fields as well