The Prevalence of Internal Labour Markets - New Evidence from Panel Data

In recent years, a small but growing literature concerned with the empirical analysis of the workings of internal labour markets has emerged. These studies, which have almost exclusively been based on personnel records data from single firms, notably Lazear (1992) and Baker, Gibbs and Holmström (1994), have begun to provide some empirical evidence on many of the issues raised by the primarily theoretical field of personnel economics. Instead of one further single firm study, this paper uses an employer-employee linked data set based on 222 Danish private sector, medium-sized or large firms during the period 1980 to 1995. The principal aim of the study is to look for evidence of internal labour markets by focussing on whether there are stable careers, whether being an incumbent has advantages for one’s subsequent career, and on to what extent and how wages are set within the firm. We also examine the influence of the external labour market on wage setting within firms. The data set allows us to examine whether firms differ, and if so, if there are industry-specific differences or differences between growing, stable, and declining firms. Moreover, our study provides insights different from those of earlier work by comparing the internal labour markets of managerial employees with those of the much less studied non-managerial workersInternal labour markets; Careers; Promotions; Firms’ wage structures

Selective nonresonant excitation of vibrational modes in suspended graphene via vibron-plasmon interaction

We theoretically study a doped graphene ribbon suspended over a trench and subject to an ac-electrical field polarized perpendicularly to the graphene plane. In such a system, the external ac-field is coupled to the relatively slow mechanical vibrations via plasmonic oscillations in the isolated graphene sheet. We show that the electrical field generates an effective pumping of the mechanical modes. It is demonstrated that in the case of underdamped plasma oscillation, a peculiar kind of geometrical resonance of the mechanical and plasma oscillations appear. Namely the efficiency of pumping significantly increases when the wave number of the mechanical mode is in close agreement with the wave number of the plasma waves. The intensity of the pumping increases with the wave number of the mode. This phenomenon allows selective actuation of different mechanical modes although the driving field is homogeneous

Nonresonant high-frequency excitation of mechanical vibrations in a movable quantum dot

Nonresonant high-frequency electrostatic actuation of a movable quantum dot (QD) is investigated analytically. The electronic dot state is in tunneling contact with a continuum of electronic states in bulk electrodes. Gate electrodes induce an electric ac-field at the dot. Absorbtion of the field is accompanied by increment or decrement of one vibrational quantum in the QD. It is shown that the rate of increment overcomes the rate of decrement of vibrational quanta when the driving frequency exceeds the inverse tunneling time between the bulk electrodes and the QD. This results in a mechanical instability, leading to relatively large amplitude oscillations of the QD, which are saturated by nonlinear dissipation

Nonresonant high frequency excitation of mechanical vibrations in graphene based nanoresonator

We theoretically analyse the dynamics of a suspended graphene membrane which is in tunnel contact with grounded metallic electrodes and subjected to ac-electrostatic potential induced by a gate electrode. It is shown that for such system the retardation effects in the electronic subsystem generate an effective pumping for the relatively slow mechanical vibrations if the driving frequency exceeds the inverse charge relax- ation time. Under this condition there is a critical value of the driving voltage ampli- tude above which the pumping overcomes the intrinsic damping of the mechanical resonator leading to a mechanical instability. This nonresonant instability is saturated by nonlinear damping and the system exhibits self-sustained oscillations of relatively large amplitude.Comment: Major revisio

TOTAL COST OF OWNERSHIP IN SALES AND MARKETING

Background: There is an internal belief within Axis that despite their products’ relatively high initial price, the total cost of ownership (TCO) of an Axis camera solution is lower than that of other brands. However, there is no internal research or tools to verify if it is true. Without this, Axis is unable to communicate their belief in an educated and quantifiable way, which is desired in sales and marketing situations. Purpose: The purpose of this master thesis is to create a TCO analysis framework for a network based video surveillance solution from a seller perspective. The framework is then to be applied on Axis’s solutions to identify and weigh the most important parameters that affect the TCO. Based on this, a TCO analysis model that can be used by Axis’s sales force is to be developed. Methodology: The overall methodology used in the project is action research in combination with descriptive, exploratory and problem-solving approaches depending on the specific research question. The theoretical methodologies have been integrated with a TCO development and implementation framework, which has formed the research process. Conclusions: Existing literature offers a range of TCO frameworks, but little research has been done regarding TCO from a seller perspective. A TCO analysis is very case specific, why generic models are not appropriate. A new framework for the development of a TCO sales tool is therefore proposed, which is adapted and provides detailed guidelines to the network camera surveillance industry. Using this framework, more than 50 cost factors that affect the TCO of a camera solution have been identified and categorised. These were then implemented into a sales tool that can be used to analyse and demonstrate costs and benefits. The significance of the cost factors affecting the TCO for a camera solution varies a lot. For sales and marketing purposes, the parameters that the company can influence and that differentiate a product from another should be emphasised. The benefits for companies to utilise TCO in sales and marketing are several, even though there are some distinct barriers to overcome. For Axis, the developed TCO sales tool can be a strategic resource to help convince its customers to shift their focus from a low-price mind-set to a pursuit of low-cost solutions

Kartläggning av seroprevalensen för influensa D-virus i svenska mjölkbesättningar

Influenza D virus, IDV, is a member of the Orthomyxoviridae family and was discovered in North America, 2011. The virus was first found in swine but has since then been found in a broad range of hosts. Studies have shown that cattle appear to be the main reservoir. The epidemiology of IDV is not fully understood, but it appears to be transmitted through direct-contact and aerosols in cattle. Experimental studies on calves have shown that IDV can infect both the upper- and lower respiratory tract but only cause mild respiratory clinical signs. Histological examinations following experimental infection have shown that IDV mainly cases cause epithelial neutrophil infiltration and mild epithelial attenuation. Immunologically there is evidence suggesting that IDV can inhibit the immune response in the host. The threat posed by IDV is the link between it and bovine respiratory disease (BRD). Studies have found that IDV is often prevalent in cattle suffering from BRD and it has been suggested that IDV infections can promote the development of BRD. This study aimed to continue the surveillance and mapping of Influenza D among dairy cattle in Sweden where a former study left off to further explore the prevalence and dynamics of IDV in Sweden. To assess the situation, 338 bulk tank milk samples were collected and analysed with an in-house indirect ELISA. The results from the study suggest that the seroprevalence of IDV in Swedish dairy herds has increased since 2019. It also appears as the seroprevalence for IDV is much higher in southern Sweden. Based on the statistical analysis performed, larger herds seem to be more likely to be positive. However, the difference in mean PP-values was not significantly different between each herd size category. This could be an indication that there are certain age groups in the herds that have elevated antibody levels.Influensa D virus, IDV, är en av medlemmarna i familjen Orthomyxoviridae och upptäcktes i Nordamerika under 2011. Viruset hittades först i svin men har sedan dess återfunnits i ett brett spektrum av värddjur. Studier har visat att nötkreatur verkar vara reservoar. Epidemiologin för IDV är inte helt klarlagd, men det verkar överföras genom direktkontakt och aerosoler hos nötkreatur. Experimentella studier på kalvar har visat att IDV kan infektera både övre- och nedre luftvägarna, men att det i de flesta fall endast orsakar milda respiratoriska kliniska tecken. Histologiska undersökningar efter experimentell infektion har visat att IDV huvudsakligen försvagar epitelet i luftvägarna och orsakar epitelial neutrofilinfiltration. Immunologiskt finns det bevis som tyder på att IDV kan hämma immunförsvaret i värddjuret. Studier har visat att IDV ofta förekommer hos nötkreatur som drabbats av bovine respiratory disease (BRD) och det har föreslagits att IDVinfektioner kan främja utvecklingen av BRD. Syftet med denna studie var att fortsätta övervakningen och kartläggningen av seroprevalensen för IDV i svenska mjölkbesättningar. En första studie på detta utfördes 2019 och tanken var att studierna skulle kunna jämföras för att påvisa förändrad förekomst och eventuella dynamiker. För att bedöma situationen samlades det in 338 mjölktanksprover och dessa analyserades med en intern indirekt ELISA. Resultaten från studien tyder på att seroprevalensen för IDV har ökat hos svenska mjölkbesättningar sedan 2019. Det verkar även som att seroprevalensen är mycket högre i södra Sverige. Baserat på den utförda statistiska analysen verkar större besättningar vara mer benägna att vara positiva för IDV. Skillnaden i genomsnittliga PP-värden skilde sig dock inte signifikant mellan storlekskategorierna. Detta skulle kunna vara en indikation på att förhöjda nivåer av IDV-antikroppar förekommer i en specifik åldersgrupp, inte hela besättningar

Röjningsformens effekt på tallens (Pinus sylvestris L.) tillväxt och kvalitetsegenskaper

Tallen (Pinus Sylvestris L.) är för den svenska skogsindustrin ett av de viktigaste trädslagen. Tallens kvalitet är påverkbar genom röjning, där röjningens intensitet och tidpunkt är avgörande för tallens diametertillväxt, årsringsbredd, kvistdiameter, krongränshöjd, stamform, juvenilvedsandel och elasticitetsmodul. Röjningsarbete utförs via olika röjningsformer, där röjningsformerna enkelställning, toppröjning, stråkröjning och korridorröjning används i svenskt skogsbruk. Studien syftade till att utreda om det fanns signifikanta skillnader i behandlingseffekt på tallens medelhöjd, medeldiameter, kvistdiameter, krongränshöjd, höjd/diameter-kvot, elasticitetsmodul och årsringsbredd mellan röjningsformerna enkelställning, toppröjning, stråkröjning och korridorröjning. Studien syftade även till att utreda om ovanstående röjningsformer hade haft effekt på sambandet mellan elasticitetsmodul och årsringsbredd, i enskilda årsskott. Det studerade försöket anlades år 2003 i tallungskog i Umeå, Västerbottens län. Beståndet var planterat med tall men bestod även av naturligt föryngrad gran (Picea abies (L.) Karst) och björk (Betula pendula Roth & Betula pubescens Ehrh.). Studiens första steg innebar inmätning och analys av ovan nämnda variabler från respektive röjningsform. Studiens andra steg innebar urval, avverkning och analys av provbitar från tallhuvudstammar. I det tredje steget analyserades effekten av röjningsformen på sambandet mellan årsringsbredd och elasticitetsmodul, i olika årsskott. Resultaten påvisade ingen signifikant effekt av röjningsformen på huvudstammarnas medelhöjd, medeldiameter, kvistdiameter, krongränshöjd höjd/diameter-kvot, årsringsbredd eller elasticitetsmodul. Resultaten visade att elasticitetsmodulen var negativt korrelerad mot årsringsbredd och att elasticitetsmodulen minskar med ökad höjd i trädet, främst på grund av att årsringsbredden ökar. Röjningsformen hade ingen effekt på sambandet. Resultaten pekar på att röjningsformen inte har avgörande betydelse för huvudstammars kvalitetsutveckling i planterade tallbestånd i norra Sverige, förutsatt att röjningstidpunkt och röjningsintensitet inte skiljer sig åt.Scots pine (Pinus sylvestris L.) is one of the most important tree species for the Swedish forest industry. Scots pine quality is influenced by pre-commercial thinning (PCT), where intensity and timing are affecting diameter growth, annual ring width, branch diameter, height to the living crown, stem form, percentage of early wood and modulus of elasticity. PCT is performed through various regimes, where traditional pre-commercial thinning, topping, corridor cleaning and pre-commercial line thinning have been used in Swedish forestry. The objective of the study was to establish if there were significant differences in treatment effects on Scots pine height, diameter, branch diameter, height to the living crown, height/diameter- ratio, modulus of elasticity and annual ring width between traditional pre-commercial thinning, topping, corridor cleaning and pre-commercial line thinning. The study also aimed to investigate if the above PCT-regimes affected the relationship between modulus of elasticity and annual ring width, in individual shoots. The studied experiment was established 2003 in Umeå, Västerbotten County, in a mixed stand dominated by planted Scots pine and naturally regenerated Norway spuce (Picea abies (L.) Karst) and birch (Betula pendula Roth & Betula pubescens Ehrh.). The studies first stage involved collecting and analysis of data from plots where the PCT-regimes were represented. Study's second stage involved harvest of selected main stems, followed by extraction and analysis of samples. Step tree analyzed the effects of PCT-regimes on the relationship between the annual ring width and modulus of elasticity in different shoots. The results showed no significant effect of the PCT-regimes on the height of the main stems, diameter, branch diameter, height to living crown, height/diameter ratio, annual ring width or modulus of elasticity. The results showed that the modulus of elasticity was negatively correlated to the annual ring width and that the modulus of elasticity decreased with increased tree height, mainly due to increased annual ring width. PCT-regime had no effect on the relationship. The results indicate that the PCT-regime has no significant impact of the quality development of main stems in planted Scots pine stands in northern Sweden, as long as the timing and intensity of the PCT are the same

Xenotransplantation : new options

Transplantation innebär att ett organ eller vävnad tas från en individ och ges till en annan individ med behov av organet eller vävnaden. Ett problem globalt är att det finns för få tillgängliga organ för transplantation. Xenotransplantation skulle kunna vara lösningen på problemet och därför har xenotransplantation från gris till människa utvärderats sedan 90-talet. Xenotransplantation innebär att organ eller vävnad tas från en individ och ges till en individ av annan art. Det ger dock upphov till fyra immunologiska avstötningsreaktioner: hyperakut-, akut humoral-, akut cellulär- och kronisk avstötning. Att utveckla metoder som förhindrar dessa avstötningsreaktioner har därför varit av stor betydelse. Frågeställning i den här litteraturstudien har rört varför avstötningsreaktioner uppstår, hur det porcina viromet påverkar förutsättningarna för xenotransplantation, hur CRISPR/Cas9systemet fungerar och hur den tekniken kan tillämpas för att driva utvecklingen med mål att göra xenotransplantation från gris till människa kliniskt möjligt. En del i problematiken med xenotransplantation mellan gris och människa är grisens endogena retrovirus (PERV). Dessa skulle kunna överföras till människor vid xenotransplantation och sedan liksom andra retrovirus orsaka immunosuppression och tumörbildning. För att förhindra dessa problem har man försökt överbrygga den genetiska skillnaden mellan människor och grisar genom genetiska modifieringar. Tack vare olika gentekniker har nu mycket av den initiala problematiken med xenotransplantation övervunnits. Den hyperakuta avstötningen har förebyggts genom att ta bort grisens gen som ger uttryck av galaktos-alfa-1,3galaktos (gal) och modifierat grisorgan så att de uttrycker humana regulatoriska komplementfaktorer vilket ytterligare har förbättrat överlevnadstiden för xenotransplantat. Med utvecklandet av CRISPR/Cas9-systemet och dess applicering inom xenotransplantation har PERV-fria grisar tagits fram. CRISPR/Cas9 är ett effektivt verktyg för modifiering av gener i eukaryota celler. Till skillnad från tidigare tekniker som ”zinc finger nucleases” (ZFN) och ”transcription activator-like effector nuclease” (TALEN) tycks CRISPR/Cas9 inducera färre risker vid genmodifiering och produktion av CRISPR/Cas9-systemet är dessutom mindre tidskrävande.Transplantation is a process where you take an organ or tissue from one person and give to another in need of a new organ or tissue. A global problem is that there are too few organs and tissue available for transplantation. Xenotransplantation could be the solution to the worldwide problem and xenotransplantation from pigs to humans has been evaluated since the 90’s. Xenotransplantation is a process where you take an organ or tissue from one individual and give it an individual of a different species. Xenotransplantation from pig to primates gives rise to 4 graft rejection reactions: hyper acute, acute vascular, acute cellular and chronic rejection. The development of methods to prevent graft rejection reactions has therefore been of great importance. In this literature review the approached questions are why graft rejection reactions occur, how the porcine virome affects the conditions for xenotransplantation, how the CRISPR/Cas9 system works and how that technology can be applied to forward the development of xenotransplantation. One of the problems with xenotransplantation between man and pig are the porcine endogenous retro virus (PERV). This has worried the scientists as the viruses could potentially be transferred to humans from pigs and then like other retroviruses cause immunosuppression and tumourgenesis. To prevent these problems, scientists have tried to bridge the genetic difference between primates and pigs through genetic engineering. Today much of the initial problems of xenotransplantation have been successfully counteracted. The hyper acute rejection has been counteracted by removing the pig's expression of gal molecules and engineering of pig organs to express human complement decay molecules has further improve the survival time of xenografts. Through the development of the CRISPR/Cas9 system and its application in xenotransplantation PERV-free pigs have been developed. CRISPR/Cas9 is an effective tool to remove and insert genes in eukaryotic cells. Unlike previous technologies, e.g. ZFN and TALEN, that were more complicated, it is more secure and less time consuming to build systems targeting specific gene sequences with the CRISPR/Cas9 technique