Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence

International audienceThe BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease

CCTV, Live and Videotapes: How Presentation Mode Affects the Evaluation of Witnesses

Videotaped and closed circuit testimonies are often used in legal procedures, but little is known about the psychological effects of these courtroom technologies. The present thesis examines how different presentation modes affect observers’ perception, veracity assessment and memory. In Study I truth-telling and lying adult witnesses were interviewed. Mock jurors (N = 122) viewed the testimonies, either live or on video, and rated their perception and assessed the veracity of the witnesses’ statements. Live observers rated the witnesses’ appearance in more positive terms and assessed them as being more honest than did video observers. Furthermore, both live and video observers’ deception detection performance was at chance level (49.2% vs. 50.8%). Live observers incorrectly believed they had a better memory of the witnesses’ statements than video observers. Study ΙΙ was structurally similar to Study I (but used child witnesses). Mock jurors (N = 136) viewed truth-telling and lying children’s testimonies (either live or on video), rated their perception of the children and assessed the children’s veracity. Live observers rated the children’s statements as being more convincing than did video observers. The overall deception detection performance was 59.6%, which was significantly different from the level of chance. Live observers were better than chance, but not better than the video observers, in assessing veracity. Moreover, live observers believed they had a better memory of the children’s statements than video observers, and they also showed a significantly better memory performance. In Study III truth-telling and lying children were viewed and assessed by adult mock jurors (N = 240) either live, via two-way closed-circuit television (CCTV), or via pre-recorded video. The mock jurors rated their perception of the children’s testimonies and assessed the children’s veracity. The results showed that live observers perceived the children in more positive terms than did the CCTV observers, who in turn perceived the children in more positive terms than did the video observers. The observers’ overall deception detection accuracy was mediocre (58.3%). Study IV investigated the effects of different camera perspectives on adults’ perception and assessment of videotaped child testimonies. Truth-telling and lying children were interviewed and videotaped simultaneously by four cameras, each taking a different visual perspective (close-up shot/child only, medium shot/child only, medium shot/child and interviewer, long shot/child and interviewer). Mock jurors (N = 256) rated their perception of the children and assessed the veracity of the statements. Children seen in long shot were perceived in more positive terms, and children seen in close-up were perceived as having to think harder. The adult’s deception detection accuracy was at chance level. Taken together, the results showed that the presentation mode affected the observers’ perception of the witnesses’ testimonies. Thus, the thesis suggests that legal policy-makers should consider the outcome of psycho-legal research on different presentation modes when establishing and/or reforming standards for police interviews and courtroom procedures

Psykisk ohälsa - interventioner och möjligheter för evidensbaserad omvårdnad

Inledning: Psykisk ohälsa är ett växande problem som ses hos både individer och i samhället i stort, det medför stora kostnader och lidande för individer och anhöriga. Många av de med psykisk ohälsa söker hjälp i primärvården men primärvården är dåligt rustade för att hjälpa dessa personer. Distriktssköterskor träffar en stor del av befolkningen och därmed många människor med psykisk ohälsa. Med anledning av detta önskar uppsatsen beskriva distriktssköterskans arbete med patienter som upplever psykisk ohälsa. Syfte: Syftet med denna studie är att sammanställa och analysera forskning om distriktssköterskors omvårdnad riktad till patienter som upplever psykisk ohälsa, ur ett primärvårdsperspektiv. Metod: Forskningsplanen är utformad som en systematisk litteraturstudie med både kvalitativa och kvantitativa data, Mixed methods. Sökning av vetenskapliga artiklar utfördes i databaserna CINAHL och PubMed, tio artiklar valdes ut till en pilotstudie. Fyra interventionsstudier respektive sex beskrivande kvalitativa och kvantitativa artiklar inkluderades. Resultat: Resultatet visade att interventioner för utbildning i själv-hjälp upplevdes som positiva och hade i varierad utsträckning effekt. Utifrån andra interventioner sågs att sjuksköterskor och distriktssköterskor hade en samordnande funktion. Förutsättningar i omvårdnaden identifierades utifrån att distriktsköterskor och sjuksköterskor var involverade i vården av patienter med upplevd psykisk ohälsa och att ett kunskapsbehov fanns. Diskussion: Distriktssköterskor och sjuksköterskor är och bör vara involverade i arbetet med psykisk ohälsa. Kompetens, position och tillgänglighet möjliggör för och gör distriktssköterskor lämpliga att arbeta med psykisk ohälsa

TCP/IP technology for modern network environments

To facilitate the merging of wireless access technologies and the traditional Internet, the core protocols for data communication should be robust and have low overhead. In this thesis, we propose refinements to the Transmission Control Protocol (TCP) that improve its cost efficiency over wireless links.TCP is unable to distinguish between congestion and error induced losses, reordered, or delayed segments. A reordering robust TCP would make it possible to simplify network elements, now performing explicit actions to prevent reordering, and open up for deployment of new technologies that naturally cause reordering. We propose TCP-Aix; a set of TCP modifications that improves the robustness of TCP to reordering and delay spikes. TCP-Aix decouples loss recovery and congestion control actions. We also present an algorithm called the winthresh algorithm for computing a duplicate acknowledgment threshold based on TCP buffer space and current send window size. The results show that TCP-Aix with the winthresh algorithm is able to maintain almost constant performance even in scenarios frequently displaying long reordering durations. It is also fair towards competing standards-compliant TCP flows.In wireless networks, where the links out of efficiency constraints are more error prone than wired links, the error and the reordering sensitivity of TCP have motivated link layer protocols that perform retransmissions and enforce in-order delivery. We investigate the potential gains of using a reordering robust TCP, like TCP-Aix, with a wireless link layer that allows out-of-order delivery, compared to using in-order delivery with a standardscompliant TCP. We found that the smoothness of TCP is strongly affected by the link layer configuration. In-order delivery leads to burstier traffic and larger network layer buffering needs, than out-of-order delivery and TCP-Aix. The interference and power consumption in foremost wireless networks make it important to reduce the communication overhead. The TCP receiver acknowledges each or every second segment. We study how to reduce the acknowledgment frequency while preserving throughput performance also in wireline networks where frequent acknowledgments generally are not problematic. To preserve throughput, the sender should use byte counting and be involved in determining the acknowledgment frequency. The results show that acknowledging four segments per send window is sufficient to maintain throughput performance also in wireline scenarios. This indicates that a lower acknowledgment frequency than provided through the delayed acknowledgment algorithm is possible today for general usage.A key service to the successful merging of traditional Internet technology and wireless cellular networks is Voice over IP (VoIP). Channels to be shared by both VoIP and TCP-based traffic is being considered for wireless cellular systems. It is challenging to provide VoIP over a shared wireless cellular channel, because VoIP is a low bitrate service with high demands on channel availability to bound the delay. The scheduling algorithm, controlling access to the channel, is central to achieve efficiency as well as to satisfy user demands. We study how a scheduler for a mix of VoIP and interactive (TCP-based) traffic should be designed for High Speed Downlink Packet Access (HSDPA). In particular, we find that slowly increasing the priority of a VoIP session relative TCP-based services is important to take advantage of the varying network conditions.Godkänd; 2008; 20080520 (ysko)</p

TCP/IP technology for modern network environments

To facilitate the merging of wireless access technologies and the traditional Internet, the core protocols for data communication should be robust and have low overhead. In this thesis, we propose refinements to the Transmission Control Protocol (TCP) that improve its cost efficiency over wireless links.TCP is unable to distinguish between congestion and error induced losses, reordered, or delayed segments. A reordering robust TCP would make it possible to simplify network elements, now performing explicit actions to prevent reordering, and open up for deployment of new technologies that naturally cause reordering. We propose TCP-Aix; a set of TCP modifications that improves the robustness of TCP to reordering and delay spikes. TCP-Aix decouples loss recovery and congestion control actions. We also present an algorithm called the winthresh algorithm for computing a duplicate acknowledgment threshold based on TCP buffer space and current send window size. The results show that TCP-Aix with the winthresh algorithm is able to maintain almost constant performance even in scenarios frequently displaying long reordering durations. It is also fair towards competing standards-compliant TCP flows.In wireless networks, where the links out of efficiency constraints are more error prone than wired links, the error and the reordering sensitivity of TCP have motivated link layer protocols that perform retransmissions and enforce in-order delivery. We investigate the potential gains of using a reordering robust TCP, like TCP-Aix, with a wireless link layer that allows out-of-order delivery, compared to using in-order delivery with a standardscompliant TCP. We found that the smoothness of TCP is strongly affected by the link layer configuration. In-order delivery leads to burstier traffic and larger network layer buffering needs, than out-of-order delivery and TCP-Aix. The interference and power consumption in foremost wireless networks make it important to reduce the communication overhead. The TCP receiver acknowledges each or every second segment. We study how to reduce the acknowledgment frequency while preserving throughput performance also in wireline networks where frequent acknowledgments generally are not problematic. To preserve throughput, the sender should use byte counting and be involved in determining the acknowledgment frequency. The results show that acknowledging four segments per send window is sufficient to maintain throughput performance also in wireline scenarios. This indicates that a lower acknowledgment frequency than provided through the delayed acknowledgment algorithm is possible today for general usage.A key service to the successful merging of traditional Internet technology and wireless cellular networks is Voice over IP (VoIP). Channels to be shared by both VoIP and TCP-based traffic is being considered for wireless cellular systems. It is challenging to provide VoIP over a shared wireless cellular channel, because VoIP is a low bitrate service with high demands on channel availability to bound the delay. The scheduling algorithm, controlling access to the channel, is central to achieve efficiency as well as to satisfy user demands. We study how a scheduler for a mix of VoIP and interactive (TCP-based) traffic should be designed for High Speed Downlink Packet Access (HSDPA). In particular, we find that slowly increasing the priority of a VoIP session relative TCP-based services is important to take advantage of the varying network conditions.Godkänd; 2008; 20080520 (ysko)</p