Sensitizing Employees’ Corporate IS Security Risk Perception

Motivated by recent practical observations of employees’ unapproved sourcing of cloud services at work, this study empirically evaluates bring your own cloud (BYOC) policies and social interactions of the IT department to sensitize employees’ security risk perception. Based on social information processing theory, BYOC strategies varying in the level of restriction from the obligatory, recommended, permitted, not regulated, to the prohibited usage of cloud services in the organization as well as social information including IT department’s policies, recommendations and responsiveness, are assessed according to their influence on employees’ perceived security risk to the organization. Results of a mixed-method approach containing expert interviews and survey data of 115 computer users in SME and large-scale enterprises analyzed using Kruskal-Wallis and WarpPLS-SEM identify the organizational-wide prohibition of and IT department’s advices against the cloud service usage at the workplace as the most effective actions to guarantee the protection of the organizational IT assets

Justifying Shadow IT Usage

Employees and/or functional managers increasingly adopt and use IT systems and services that the IS management of the organization does neither provide nor approve. To effectively counteract such shadow IT in organizations, the understanding of employees’ motivations and drivers is necessary. However, the scant literature on this topic primarily focused on various governance approaches at firm level. With the objective to open the black box of shadow IT usage at the individual unit of analysis, we develop a research model and propose a laboratory experiment to examine users’ justifications for violating implicit and explicit IT usage restrictions based on neutralization theory. To be precise, in this research-in-progress, we posit positive associations between shadow IT usage and human tendencies to downplay such kind of rule-breaking behaviors due to necessity, no injury, and injustice. We expect a lower impact of these neutralization effects in the presence of behavioral IT guidelines that explicitly prohibit users to employ exactly those shadow IT systems

Energy and Economic Performance of Solar Cooling Systems World Wide

AbstractSolar thermal cooling systems have been installed as pilot projects in most regions of the world, but due to the low number of total installations there is not yet much experience available about system sizing and design. To counter the lack of experience and to evaluate the potential of energy efficient solar cooling systems, a systematic system design study has been carried out covering most climatic regions worldwide. For each technology investigated, an energy optimized control strategy was developed which maximizes the primary energy efficiency. This control strategy was implemented in the simulation environment INSEL and system models were developed for a range of thermal cooling technologies and validated with operating experiences from different plants monitored by the authors.It could be shown that a reduction of nominal chiller power by 30% to 40% or more hardly effects the solar cooling fraction for most climates, but significantly increases the machine operating hours and thus improves the economics. The lower the nominal power of the chiller, the higher the recommended ratio of collector surface area per kW. For a given machine nominal power, solar cooling fractions increase with collector surface area until saturation is reached. Collector surface areas can be as high as 5 m2 to 10 m2 per kW with still increasing solar cooling fractions, but acceptable specific collector yield reduction. The economic optimum is reached for less solar cooling fraction and thus lower primary energy savings. Single effect absorption cooling systems easily reach 80% solar cooling fraction for all but very humid climates. Primary energy ratios can be over 3.0, depending on system design and cooling load data. CO2 and primary energy savings of 30 – 79% are achievable.The economic study showed that solar thermal cooling is more viable in hot climates than in moderate European climates. Annual costs strongly depend on the locations. The specific costs per kWh cooling in German locations vary between 0.25 and 1.01 €/kWh, in Spanish locations between 0.13 and 0.30 €/kWh. In hot climates like Jakarta and Riyadh the specific costs are as low as 0.09 to 0.15 €/kWh. Furthermore the maximum investment costs were calculated get a payback time of 10 years

Anwendung und Bewertung numerischer und experimenteller Methoden zur Analyse und Entwicklung eines Zweitakt-Freikolbenmotors

Die vorliegende Arbeit behandelt die Untersuchung und Entwicklung des verbrennungsmotorischen Teilsystems eines Freikolbenmotors mit elektrischer Energieauskopplung. Dieser sogenannte Freikolbenlineargenerator (FKLG) zeichnet sich durch einen freischwingenden Aufbau ohne die mechanische Zwangsführung eines Kurbeltriebes aus. Der Verbrennungskolben, der Läufer des Lineargenerators und der Gasfederkolben sind zu einer Kolbeneinheit zusammengefasst, die zwischen der Gasfeder und dem verbrennungsmotorischen Brennraum schwingt. Dieser Aufbau führt zu neuen Freiheitsgraden in der verbrennungsmotorischen Prozessführung, da Verdichtungsverhältnis und Kolbenhubkurve variabel angepasst werden können. Ein mögliches Anwendungsgebiet des Freikolbenlineargenerators ist der Einsatz als mobile Stromerzeugungseinheit in einem batterieelektrischen Fahrzeug. In vorangegangenen Arbeiten wurden der Lineargenerator, die Gasfeder und das verbrennungsmotorische Teilsystem der ersten Generation entwickelt und untersucht. Dies erfolgte schwerpunktmäßig im Hinblick auf die Regelung eines freischwingenden Gesamtsystems. Die vorliegende Arbeit rückt die Prozesse im Brennraum des verbrennungsmotorischen Teilsystems in den Vordergrund. Die Herausforderungen des Zweitakt-Arbeitsprozesses im Freikolbenlineargenerator sind der ventilgesteuerte Ladungswechsel mit Kopfumkehrspülung, die innere Gemischbildung und die Verbrennung bei hohen Restgasgehalten. Zur Analyse und Optimierung dieser innermotorischen Vorgänge werden Entwicklungsverfahren ausgearbeitet, angewendet und bewertet. Das Zielbild ist dabei ein effizienter, stabiler und emissionsarmer verbrennungsmotorischer Prozess unter Ausnutzung der konzeptbedingten Variabilitäten. Durch den Einsatz eines vollvariablen Ventiltriebsystems unterscheiden sich die Bedingungen des Ladungswechsels im kopfumkehrgespülten Brennraum des FKLG deutlich von denen in klassischen schlitzgesteuerten Zweitakt-Motoren. Das Entwicklungsverfahren zur Analyse der innermotorischen Strömungsfelder während des Ladungswechsels kombiniert Particle Image Velocimetry (PIV) Messungen mit strömungsmechanischen Simulationen. Hierzu wurde ein Prüfstandsaufbau entwickelt, der eine Vermessung der Strömungsfelder im ungefeuerten Betrieb erlaubt. Simulations- und Messergebnisse zeigen übereinstimmend eine Überlagerung aus Tumble- und Drall-Strömung im Zylinder. Während sich die Simulation zur Voraussage der charakteristischen Strömungsstrukturen sehr gut eignet, sind der Genauigkeit, mit der lokale Strömungsgeschwindigkeiten berechnet werden können, Grenzen gesetzt. Der dargelegte laserdiagnostische Messaufbau erlaubt eine Einordnung der Simulationsergebnisse und sichert damit die Analyse der Zylinderinnenströmung wesentlich ab. Das Entwicklungsverfahren zur Untersuchung einer homogenen selbstzündenden Verbrennung in einem verbrennungsmotorischen Teilsystem der zweiten Generation basiert auf der Kombination von strömungsmechanischen Simulationen mit experimentellen Untersuchungen am Verbrennungsmotorprüfstand. Dabei wird ein auf innermotorische Anwendungen optimierter Simulationsansatz eingesetzt, der die strömungsmechanischen Vorgänge im Brennraum und den strömungsführenden Kanälen über mehrere Arbeitsspiele bei vergleichsweise geringen Rechenzeiten räumlich abbildet. In der vorliegenden Arbeit wird der Entwicklungsprozess von Auslegungssimulationen über die Konstruktion bis hin zur experimentellen Untersuchung eines homogenen selbstzündenden Brennverfahrens im neuen Versuchsträger beschrieben. Das verbrennungsmotorische Teilsystem der zweiten Generation ermöglicht Betriebsstrategien mit innerer Abgasrückführung, sodass durch hohe Restgasgehalte eine Selbstzündung der Zylinderladung eingeleitet wird. Am hydraulisch unterstützten Verbrennungsmotorprüfstand wird erstmalig ein homogenes selbstzündendes Brennverfahren in einem Freikolbenmotor dieser Bauart experimentell untersucht. Die Messergebnisse weisen nach, dass eine dynamische Anpassung der Kolbenbewegung positiv zur Steuerung des Zündzeitpunktes und damit der Wärmefreisetzung genutzt werden kann. Die ermittelten Druckanstiegsraten liegen bei gleichem Mitteldruck deutlich unter den Vergleichswerten von kurbelwellenbasierten Verbrennungsmotoren mit homogener Selbstzündung. Der eingesetzte innovative Simulationsansatz zeigt sich als ideales Werkzeug zur Analyse und Auslegung des verbrennungsmotorischen Teilsystems. Im Zuge der Entwicklung des verbrennungsmotorischen Teilsystems der zweiten Generation zeigte sich, dass zur Verbesserung der Gemischbildung und -aufbereitung eine genauere Betrachtung des Einspritzvorgangs erforderlich ist. Das hierzu angewandte Entwicklungsverfahren kombiniert räumlich hochaufgelöste Strömungssimulationen mit laserinduzierten Fluoreszenz (LIF) Messungen. Die laserdiagnostische Untersuchung des Einspritzvorgangs erfolgt an einem optisch zugänglichen Versuchsträger im gefeuerten Betrieb. Es wird ein Messaufbau des LIF Verfahrens eingesetzt, der das bestrahlende Laserlicht und das Fluoreszenzsignal durch nur ein Fenster im Kolbenboden in den Brennraum ein- und auskoppelt. Ein Vergleich der Simulation mit laserdiagnostischen Messergebnissen zeigt, dass erst durch eine iterative Anpassung der Einspritzrichtung jedes Spraykegels die Kraftstoffausbreitung in der Simulation realitätsnah wiedergegeben wird. Das Entwicklungsverfahren verdeutlicht, dass trotz des höheren Detaillierungsgrades des Simulationsansatzes eine Untersuchung des Einspritzvorgangs ausschließlich auf Basis von Strömungssimulationen nicht verlässlich und ein Abgleich mit Messdaten entsprechend wichtig ist. Durch die Anwendung der in dieser Arbeit vorgestellten Entwicklungsverfahren werden wichtige grundlegende Erkenntnisse über die innermotorischen Vorgänge im verbrennungsmotorischen Teil des Freikolbenlineargenerators erlangt. Im Hinblick auf eine weiterführende Entwicklung des Motorenkonzeptes bildet die Arbeit eine Basis für den zielgerichteten Einsatz numerischer und laserdiagnostischer Methoden

In vivo analysis of staphylococcus aureus-infected mice reveals differential temporal and spatial expression patterns of fhuD2

Staphylococcus aureus is an opportunistic human pathogen and a major cause of invasive infections such as bacteremia, endocarditis, pneumonia and wound infections. FhuD2 is a staphylococcal lipoprotein involved in the uptake of iron-hydroxymate and is under the control of the iron uptake regulator Fur. The protein is part of an investigational multi-component vaccine formulation that has shown protective efficacy in several murine models of infection. Even though fhuD2 expression was shown to be upregulated in murine kidneys infected with S. aureus, it is unknown whether the bacterium undergoes increased iron deprivation during prolonged infection. Furthermore, different infection niches of S. aureus might provide different environments and iron availability resulting in different fhuD2 expression pattern within different host organs. To address these questions, we characterized the in vitro expression of the fhuD2 gene and confirmed Fur-dependent iron-regulation of its expression. We further investigated its expression in mice infected with a bioluminescent reporter strain of S. aureus expressing the luciferase operon under the control of the fhuD2 promoter. The emission of bioluminescence in different organs was followed over a seven-day time course, as well as quantitative real-time PCR analysis of the RNA transcribed from the endogenous fhuD2 gene. Using this approach, we could show that fhuD2 expression was induced during infection in all organs analyzed and that differences in expression were observed in the temporal expression profiles, and between infected organs. Our data suggest that S. aureus undergoes increased iron deprivation during progression of infection in diverse host organs and accordingly induces dedicated iron acquisition mechanisms. Since FhuD2 plays a central role in providing the pathogen with the required iron, further knowledge of the patterns of fhuD2 expression in vivo during infection is instrumental in better defining the role of this antigen in S. aureus pathogenesis and as a vaccine antigen

Absence of protein A expression is associated with higher capsule production in staphylococcal isolates

Staphylococcus aureus is a major human pathogen, and a leading cause of soft tissue and blood stream infections. One of the causes of its success as a pathogen is the peculiar array of immune evasion factors through which the bacterium avoids host defenses, where the staphylococcal protein A (SpA) plays a major role thanks to its IgG binding activities. Moreover, SpA has recently been proposed as a promising vaccine antigen. In this study, we evaluated the expression of SpA in a collection of staphylococcal strains, about 7% of which did not express SpA (SpA- strains), despite the presence of the gene. By a comparative genomic analysis, we identified that a mutation in the spa 5′ UTR sequence affecting the RBS is responsible for the loss of SpA in a subset of SpA- strains. Using a high-throughput qRT-PCR approach on a selected panel of virulence-related genes, we identified that the SpA- phenotype is associated with lower spa transcript levels and increased expression and production of capsule as well as other changes in the transcription of several key virulence factors. Our data suggest that the SpA- phenotype has occurred in geographically distinct strains through different molecular mechanisms including both mutation, leading likely to translation alterations, and transcriptional deregulation. Furthermore, we provide evidence that SpA- strains are highly susceptible to phagocytic uptake mediated by anti-capsule antibodies. These data suggest that S. aureus may alter its virulence factor expression pattern as an adaptation to the host or environment. Vaccination strategies targeting both SpA and capsule could therefore result in broader coverage against staphylococcal isolates than SpA alone

Staphylococcus aureus in animals

Staphylococcus aureus is a mammalian commensal and opportunistic pathogen that colonizes niches such as skin, nares and diverse mucosal membranes of about 20-30% of the human population. S. aureus can cause a wide spectrum of diseases in humans and both methicillin-sensitive and methicillin-resistant strains are common causes of nosocomial- and community-acquired infections. Despite the prevalence of literature characterising staphylococcal pathogenesis in humans, S. aureus is a major cause of infection and disease in a plethora of animal hosts leading to a significant impact on public health and agriculture. Infections in animals are deleterious to animal health, and animals can act as a reservoir for staphylococcal transmission to humans. Host-switching events between humans and animals and amongst animals are frequent and have been accentuated with the domestication and/or commercialisation of specific animal species. Host-switching is typically followed by subsequent adaptation through acquisition and/or loss of mobile genetic elements such as phages, pathogenicity islands and plasmids as well as further host-specific mutations allowing it to expand into new host populations. In this chapter, we will be giving an overview of S. aureus in animals, how this bacterial species was, and is, being transferred to new host species and the key elements thought to be involved in its adaptation to new ecological host niches. We will also highlight animal hosts as a reservoir for the development and transfer of antimicrobial resistance determinants

Respiratory viruses interacting with cells: the importance of electrostatics

The COVID-19 pandemic has rekindled interest in the molecular mechanisms involved in the early steps of infection of cells by viruses. Compared to SARS-CoV-1 which only caused a relatively small albeit deadly outbreak, SARS-CoV-2 has led to fulminant spread and a full-scale pandemic characterized by efficient virus transmission worldwide within a very short time. Moreover, the mutations the virus acquired over the many months of virus transmission, particularly those seen in the Omicron variant, have turned out to result in an even more transmissible virus. Here, we focus on the early events of virus infection of cells. We review evidence that the first decisive step in this process is the electrostatic interaction of the spike protein with heparan sulfate chains present on the surface of target cells: Patches of cationic amino acids located on the surface of the spike protein can interact intimately with the negatively charged heparan sulfate chains, which results in the binding of the virion to the cell surface. In a second step, the specific interaction of the receptor binding domain (RBD) within the spike with the angiotensin-converting enzyme 2 (ACE2) receptor leads to the uptake of bound virions into the cell. We show that these events can be expressed as a semi-quantitative model by calculating the surface potential of different spike proteins using the Adaptive Poison-Boltzmann-Solver (APBS). This software allows visualization of the positive surface potential caused by the cationic patches, which increased markedly from the original Wuhan strain of SARS-CoV-2 to the Omicron variant. The surface potential thus enhanced leads to a much stronger binding of the Omicron variant as compared to the original wild-type virus. At the same time, data taken from the literature demonstrate that the interaction of the RBD of the spike protein with the ACE2 receptor remains constant within the limits of error. Finally, we briefly digress to other viruses and show the usefulness of these electrostatic processes and calculations for cell-virus interactions more generally