E-commerce and prices - theory and evidence

This paper examines the relation between prices in conventional stores and on the Internet. Main results from the theoretical analysis are i) we expect a discrete fall in prices in conventional stores as the share of the population with access to Internet reaches a critical level, ii) the relation between prices depends on convenience costs of shopping in regular stores as well as on transport and navigation costs for goods bought over Internet, iii) retailers who only sell through Internet have lower on-line prices than retailers who also sell through conventional stores. The empirical section employs a rich data set covering the Swedish markets for books and CDs. Prices of these goods are on average 15 percent lower on Internet, but if a single item is bought transport costs will make it as expensive to buy over Internet as in a regular store (if a basket of goods is bought it is some 10 percent cheaper on Internet since transport costs are fixed). There is firm support for that retailers who only sell over Internet have lower on-line prices.retail pricing; consumer behavior; e-commerce; price discrimination; Internet

Missing People - En studie av organisationers kommunikation via sociala medier

Detta är en B-uppsats skriven av Mattias Torstensson och Amanda Sandström. Uppsatsen är skriven i ämnet Medie- och kommunikationsvetenskap vid institutionen för kommunikation och medier på Lunds universitet. Uppsatsens titel är ”Missing People – En studie av organisationers kommunikation via sociala medier”. Uppsatsen syftar till att med utgångspunkt i den nystartade hjälporganisationen Missing people och deras kommunikation via sociala medier granska dels hur nya kommunikationsmöjligheter påverkat synen på traditionell teori om organisationskommunikation men också att se till de problem och möjligheter samma kommunikationsmöjligheter givit moderna organisationer. Vi utgår från traditionella organisationskommunikations-teorier om en uppdelning mellan intern och extern kommunikation och studerar vad som händer när de sociala medierna fått en viktig roll i organisationers kommunikation. Vi definierar också vad en organisation är idag. Vårt empiriska material har samlats in genom observationer och kvalitativa textanalyser. Vår slutsats är att de nya kommunikationsmöjligheterna gjort det svårare att definiera vad som är en organisation och vilka som ingår i den och att gränsen mellan intern och extern kommunikation har upplösts på grund av detta

Peak Bone Mass and Quantitative Ultrasound Bone Properties in Young Adulthood : A Study in the PEAK-25 Cohort of Women

Peak bone mass is normally reached in the third decade of life. Previously, in the population-based PEAK-25 cohort (n = 1061, age 25.5 ± 0.2), we demonstrated that bone mineral density in the population-based PEAK-25 cohort is comparatively high; therefore, this study aimed to determine if the calcaneus microarchitecture mirrored this. In the process, we describe normative quantitative ultrasound (QUS) values for 25-yr-old women and the relationship between QUS values and extremes of body weight. QUS variables speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness index were measured. Young adult values were based on the manufacturer-supplied QUS reference values. Analyses were performed in the cohort as a whole, and additionally, to understand the relationship between body weight and QUS values in young women, the variables were categorized into octiles for weight or body mass index (BMI) and the lowest and highest octiles were compared. In the cohort, SOS values, reflecting bone density, were higher (108 ± 18%), whereas BUA values, reflecting bone complexity, were lower (90 ± 14%) compared to the young adult reference population. SOS did not correlate with body weight or BMI. In the cohort, overall correlations between BUA weight, and BMI were small and positive (Pearson's r coefficients 0.261 and 0.197, respectively; p <0.001), although in the low-weight group, r coefficients were higher (r = 0.313 and 0.268; p <0.05). In contrast, in the high-weight group, correlation with BUA values tended to be small, negative, and nonsignificant. Correlation between QUS and dual-energy X-ray absorptiometry-measured bone mineral density was low to moderate and significant at all skeletal sites (r = 0.37-0.52). Whereas coefficients tended to be higher in the low-weight group, the reverse was apparent for the low-BMI group. In these 25-yr-old women, a comparatively high dual-energy X-ray absorptiometry-measured bone mass is offset by less complex bone structures assessed by QUS. This may have implications for later osteoporosis assessment and future fracture risk

Lessons on Tumour Response: Imaging during Therapy with 177Lu-DOTA-octreotate. A Case Report on a Patient with a Large Volume of Poorly Differentiated Neuroendocrine Carcinoma

Favourable outcomes of peptide receptor radiotherapy (PRRT) of neuroendocrine tumours have been reported during the last years. Still, there are uncertainties on the radionuclides to be used, the treatment planning, and the indication in patients with a high proliferation rate

Моделирование потребления активной мощности насосных агрегатов с изменяющимся режимом водопотребления

Материалы XX Междунар. науч.-техн. конф. студентов, аспирантов и молодых ученых, Гомель, 23–24 апр. 2020 г

Förvaltning av signalkräfta i sjöar

Fisket efter signalkräfta har fått allt större ekonomisk och social betydelse i Sverige. Trots detta saknas väl underbyggda råd för hur ett hållbart fiske ska bedrivas.  Projektet ”Utveckling av fisket efter signalkräfta – hur ska man optimera fiske och förutsäga risken för populationskollapser?” är ett projekt som delfinansieras av Europeiska fiskerifonden 2009-2013. Som en inledande del i detta projekt gjordes en litteratursammanställning, och baserat på denna har planeringen av det framtida arbetet kunnat konkretiseras.  Målsättningen med litteraturgenomgången var att identifiera vilken information om signalkräftans biologi och ekologi som behövdes för att kunna ta fram bra fiskerimodeller för hur ett hållbart fiske bör bedrivas. Dessutom var det viktigt att förstå varför vissa bestånd av signalkräfta har kollapsat.  Fångsterna av signalkräfta varierar mellan sjöar. Denna variation kan, i sjöar som inte är försurade, till stor del förklaras med hur stor andel av sjöns botten som är täckt med sten. Finns det mycket sten i en sjö finns det också mycket signalkräftor. Det finns några få studier i Sverige på signalkräftan där populationer har följts under en längre tid (minst 15 år). Dessa visar att fångst per mjärde och uttag av konsumtionskräftor varierar mellan olika år inom en sjö. Dessa variationer kan till viss del förklaras med temperaturen under föregående år, men mekanismen bakom detta är inte känd. Studier av andra arter sötvattenskräftor och en del marina skaldjur (t.ex. hummer) tyder på att rekryteringen (reproduktionsframgången) till viss del kan förklara variationerna i fångstnivåer mellan olika år.  Denna litteraturgenomgång visar att det saknas väsentlig information om signalkräftans ekologi och biologi för att kunna ta fram teoretiska modeller som ska ligga till grund för rekommendationer om hur ett hållbart fiske ska bedrivas. De beståndsanalyser som bedömts vara intressanta för signalkräfta kräver vissa dataunderlag för att ge tillförlitliga resultat. De enskilt viktigaste faktorerna är rekryteringsframgång, tillväxt, naturlig dödlighet, och detaljerad fiskeristatistik (ansträngning, selektivitet, fångster etc.). Med anledning av resultaten från denna litteraturgenomgång bedömdes följande insatser som prioriterade:  • undersöka betydelsen av honans storlek för rekryteringsframgång • utveckla tekniken för märkning av kräftor i olika typer av bestånd för att sedan kunna använda återfångstdata för att bestämma individuell tillväxt, naturlig dödlighet och fiskeridödlighet  • uppskatta ytan tillgängligt kräfthabitat för olika kräftbestånd och bedöma i vilken mån det påverkar potentiellt fiskeuttag  • analysera ett flertal sjöar med och utan populationskollapser och undersöka vilka miljöfaktorer som kan förklara uppkomsten av kollapser  • analysera såväl pestfrekvens som infektionsgrad i enskilda kräftor och utvärdera om det finns en koppling mellan populationskollapser och ökade pestangrepp i sjöa

Noise correlation in PET, CT, SPECT and PET/CT data evaluated using autocorrelation function: a phantom study on data, reconstructed using FBP and OSEM

BACKGROUND: Positron Emission Tomography (PET), Computed Tomography (CT), PET/CT and Single Photon Emission Tomography (SPECT) are non-invasive imaging tools used for creating two dimensional (2D) cross section images of three dimensional (3D) objects. PET and SPECT have the potential of providing functional or biochemical information by measuring distribution and kinetics of radiolabelled molecules, whereas CT visualizes X-ray density in tissues in the body. PET/CT provides fused images representing both functional and anatomical information with better precision in localization than PET alone. Images generated by these types of techniques are generally noisy, thereby impairing the imaging potential and affecting the precision in quantitative values derived from the images. It is crucial to explore and understand the properties of noise in these imaging techniques. Here we used autocorrelation function (ACF) specifically to describe noise correlation and its non-isotropic behaviour in experimentally generated images of PET, CT, PET/CT and SPECT. METHODS: Experiments were performed using phantoms with different shapes. In PET and PET/CT studies, data were acquired in 2D acquisition mode and reconstructed by both analytical filter back projection (FBP) and iterative, ordered subsets expectation maximisation (OSEM) methods. In the PET/CT studies, different magnitudes of X-ray dose in the transmission were employed by using different mA settings for the X-ray tube. In the CT studies, data were acquired using different slice thickness with and without applied dose reduction function and the images were reconstructed by FBP. SPECT studies were performed in 2D, reconstructed using FBP and OSEM, using post 3D filtering. ACF images were generated from the primary images, and profiles across the ACF images were used to describe the noise correlation in different directions. The variance of noise across the images was visualised as images and with profiles across these images. RESULTS: The most important finding was that the pattern of noise correlation is rotation symmetric or isotropic, independent of object shape in PET and PET/CT images reconstructed using the iterative method. This is, however, not the case in FBP images when the shape of phantom is not circular. Also CT images reconstructed using FBP show the same non-isotropic pattern independent of slice thickness and utilization of care dose function. SPECT images show an isotropic correlation of the noise independent of object shape or applied reconstruction algorithm. Noise in PET/CT images was identical independent of the applied X-ray dose in the transmission part (CT), indicating that the noise from transmission with the applied doses does not propagate into the PET images showing that the noise from the emission part is dominant. The results indicate that in human studies it is possible to utilize a low dose in transmission part while maintaining the noise behaviour and the quality of the images. CONCLUSION: The combined effect of noise correlation for asymmetric objects and a varying noise variance across the image field significantly complicates the interpretation of the images when statistical methods are used, such as with statistical estimates of precision in average values, use of statistical parametric mapping methods and principal component analysis. Hence it is recommended that iterative reconstruction methods are used for such applications. However, it is possible to calculate the noise analytically in images reconstructed by FBP, while it is not possible to do the same calculation in images reconstructed by iterative methods. Therefore for performing statistical methods of analysis which depend on knowing the noise, FBP would be preferred

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

"Why does not the red light come on?" : Guidelines regarding color scheme for good availability of information on the web for people with defective color vision.

Omkring 10% av befolkningen lider av defekt färgseende. De flesta, upptill 99%, av dessa är röd-grön färgblinda. Den sista procenten delasmellan totalt färgblinda och de med gul-blå färgblindhet. I studienidentifieras riktlinjer för hur färgsättning av diagram och kurvor ska görasför att även de med någon av de nämnda typerna av defekt färgseende skakunna tillgodogöra sig informationen i till exempel diagram. Baserat påteorier, samt egen personlig erfarenhet skapades bilder på färgsattakurvdiagram anpassade för personer med röd-grön färgblindhet. Dessahar testats och utvärderats av informanter som lever med den typen avdefekt färgseende. Detsamma gäller för skapandet av bilder för de medblå-gul färgblindhet. En färgsättning med enbart grundfärgerna gul, rödoch blå tillsammans med svart visade sig fungera för båda typerna avdefekt färgseende. Dessa färger tillsammans med svart mot en vitbakgrund ger inte bara ett tydligt intryck utan är också estetiskttilltalande.Genom att göra olika markeringar av linjerna i form av olika typer avsträckningar eller punkter, kan lätt fler än fyra kurvor finnas i sammadiagram. I studien presenteras möjliga färgkombinationer ochförklaringar kring varför de fungerar ihop. Detta bör vara tidsbesparandeoch kostnadseffektivt vid färgsättning av diagram likväl som webbsidoroch grafiska användargränssnitt mm. Informanternas tips och idéer på hurman ytterligare kan underlätta för de med defekt färgseende finns ocksåmed i rapporten.Approximately 10% of the population suffer from defective color vision. Up to 99%of these persons suffer from red-green defective color vision. The last percentage isshared between those that are totally colorblind and those suffering from yellow-bluecolor defective color vison. This study identifies how correct use of colors will makesure that people suffering from any of the above-mentioned types of defective colorvision conditions will be able to assimilate the information given in, for example, adiagram. Based on theories, as well as personal experience, images were created oncolored curve diagrams adapted for people with red-green color blindness. These havebeen tested and evaluated by informants living with that type of defective colorvision. The same applies when it comes to the creation of the pictures for thosesuffering from blue-yellow defective color vision.A color scheme using only the primary colors yellow, red and blue together withblack proved to work for both types of defective color vision. These colors togetherwith black on a white background not only give a clear impression but are alsoaesthetically appealing. By making different markings of the lines in the form ofdashed lines or dots, more than four curves can easily be found in the same diagram.The study presents possible combinations of colors and explanations to why theywork together. This should be time saving and cost effective when coloring diagrams and also when for example coloring webpages and graphical user interfaces. The tipsand ideas given by the informants how to further facilitate for the persons sufferingfrom defective color vision is also found in the report