Use of modal flexibility method to detect damage in suspended cables and the effects of cable parameters

Modal flexibility is a widely accepted technique to detect structural damage using vibration characteristics. Its application to detect damage in long span large diameter cables such as those used in suspension bridge main cables has not received much attention. This paper uses the modal flexibility method incorporating two damage indices (DIs) based on lateral and vertical modes to localize damage in such cables. The competency of those DIs in damage detection is tested by the numerically obtained vibration characteristics of a suspended cable in both intact and damaged states. Three single damage cases and one multiple damage case are considered. The impact of random measurement noise in the modal data on the damage localization capability of these two DIs is next examined. Long span large diameter cables are characterized by the two critical cable parameters named bending stiffness and sag-extensibility. The influence of these parameters in the damage localization capability of the two DIs is evaluated by a parametric study with two single damage cases. Results confirm that the damage index based on lateral vibration modes has the ability to successfully detect and locate damage in suspended cables with 5% noise in modal data for a range of cable parameters. This simple approach therefore can be extended for timely damage detection in cables of suspension bridges and thereby enhance their service during their life spans.

Intravascular device administration sets: Replacement after standard versus prolonged use in hospitalised patients--a study protocol for a randomised controlled trial (The RSVP Trial)

Introduction Vascular access devices (VADs), such as peripheral or central venous catheters, are vital across all medical and surgical specialties. To allow therapy or haemodynamic monitoring, VADs frequently require administration sets (AS) composed of infusion tubing, fluid containers, pressure-monitoring transducers and/or burettes. While VADs are replaced only when necessary, AS are routinely replaced every 3–4 days in the belief that this reduces infectious complications. Strong evidence supports AS use up to 4 days, but there is less evidence for AS use beyond 4 days. AS replacement twice weekly increases hospital costs and workload. Methods and analysis This is a pragmatic, multicentre, randomised controlled trial (RCT) of equivalence design comparing AS replacement at 4 (control) versus 7 (experimental) days. Randomisation is stratified by site and device, centrally allocated and concealed until enrolment. 6554 adult/paediatric patients with a central venous catheter, peripherally inserted central catheter or peripheral arterial catheter will be enrolled over 4 years. The primary outcome is VAD-related bloodstream infection (BSI) and secondary outcomes are VAD colonisation, AS colonisation, all-cause BSI, all-cause mortality, number of AS per patient, VAD time in situ and costs. Relative incidence rates of VAD-BSI per 100 devices and hazard rates per 1000 device days (95% CIs) will summarise the impact of 7-day relative to 4-day AS use and test equivalence. Kaplan-Meier survival curves (with log rank Mantel-Cox test) will compare VAD-BSI over time. Appropriate parametric or non-parametric techniques will be used to compare secondary end points. p Values of <0.05 will be considered significant.

Effectiveness of electrocardiographic guidance in CVAD tip placement

Background International standard practice for the correct confirmation of the central venous access device is the chest X-ray. The intracavitary electrocardiogram-based insertion method is radiation-free, and allows real-time placement verification, providing immediate treatment and reduced requirement for post-procedural repositioning. Methods Relevant databases were searched for prospective randomised controlled trials (RCTs) or quasi RCTs that compared the effectiveness of electrocardiogram-guided catheter tip positioning with placement using surface-anatomy-guided insertion plus chest X-ray confirmation. The primary outcome was accurate catheter tip placement. Secondary outcomes included complications, patient satisfaction and costs. Results Five studies involving 729 participants were included. Electrocardiogram-guided insertion was more accurate than surface anatomy guided insertion (odds ratio: 8.3; 95% confidence interval (CI) 1.38; 50.07; p=0.02). There was a lack of reporting on complications, patient satisfaction and costs. Conclusion The evidence suggests that intracavitary electrocardiogram-based positioning is superior to surface-anatomy-guided positioning of central venous access devices, leading to significantly more successful placements. This technique could potentially remove the requirement for post-procedural chest X-ray, especially during peripherally inserted central catheter (PICC) line insertion.

Predicting surgical outcomes for paediatric spinal deformity patients using subject specific finite element models

INTRODUCTION Adolescent idiopathic scoliosis (AIS) is a spinal deformity, which may require surgical correction by attaching rods to the patient’s spine using screws inserted into the vertebrae. Complication rates for deformity correction surgery are unacceptably high. Determining an achievable correction without overloading the adjacent spinal tissues or implants requires an understanding of the mechanical interaction between these components. Our novel patient specific modelling software creates individualized finite element models (FEM) representing the thoracolumbar spine and ribcage of scoliosis patients. We have recently applied the model to investigate the influence of increasing magnitudes of surgically applied corrective force on predicted deformity correction...

Effects of Tamoxifen and oestrogen on histology and radiographic density in high and low mammographic density human breast tissues maintained in murine tissue engineering chambers

Mammographic density (MD) is a strong risk factor for breast cancer. It is altered by exogenous endocrine treatments, including hormone replacement therapy and Tamoxifen. Such agents also modify breast cancer (BC) risk. However, the biomolecular basis of how systemic endocrine therapy modifies MD and MD-associated BC risk is poorly understood. This study aims to determine whether our xenograft biochamber model can be used to study the effectiveness of therapies aimed at modulating MD, by examine the effects of Tamoxifen and oestrogen on histologic and radiographic changes in high and low MD tissues maintained within the biochamber model. High and low MD human tissues were precisely sampled under radiographic guidance from prophylactic mastectomy fresh specimens of high-risk women, then inserted into separate vascularized murine biochambers. The murine hosts were concurrently implanted with Tamoxifen, oestrogen or placebo pellets, and the high and low MD biochamber tissues maintained in the murine host environment for 3 months, before the high and low MD biochamber tissues were harvested for histologic and radiographic analyses. The radiographic density of high MD tissue maintained in murine biochambers was decreased in Tamoxifen-treated mice compared to oestrogen-treated mice (p = 0.02). Tamoxifen treatment of high MD tissue in SCID mice led to a decrease in stromal (p = 0.009), and an increase in adipose (p = 0.023) percent areas, compared to placebo-treated mice. No histologic or radiographic differences were observed in low MD biochamber tissue with any treatment. High MD biochamber tissues maintained in mice implanted with Tamoxifen, oestrogen or placebo pellets had dynamic and measurable histologic compositional and radiographic changes. This further validates the dynamic nature of the MD xenograft model, and suggests the biochamber model may be useful for assessing the underlying molecular pathways of Tamoxifen-reduced MD, and in testing of other pharmacologic interventions in a preclinical model of high MD.

Histopathological features of bone regeneration in a canine segmental ulnar defect model

Background Today, finding an ideal biomaterial to treat the large bone defects, delayed unions and non-unions remains a challenge for orthopaedic surgeions and researchers. Several studies have been carried out on the subject of bone regeneration, each having its own advantages. The present study has been designed in vivo to evaluate the effects of cellular auto-transplantation of tail vertebrae on healing of experimental critical bone defect in a dog model. Methods Six indigenous breeds of dog with 32 ± 3.6 kg average weight from both sexes (5 males and 1 female) received bilateral critical-sized ulnar segmental defects. After determining the health condition, divided to 2 groups: The Group I were kept as control I (n = 1) while in Group II (experimental group; n = 5) bioactive bone implants were inserted. The defects were implanted with either autogeneic coccygeal bone grafts in dogs with 3-4 cm diaphyseal defects in the ulna. Defects were stabilized with internal plate fixation, and the control defects were not stabilized. Animals were euthanized at 16 weeks and analyzed by histopathology. Results Histological evaluation of this new bone at sixteen weeks postoperatively revealed primarily lamellar bone, with the formation of new cortices and normal-appearing marrow elements. And also reformation cortical compartment and reconstitution of marrow space were observed at the graft-host interface together with graft resorption and necrosis responses. Finally, our data were consistent with the osteoconducting function of the tail autograft. Conclusions Our results suggested that the tail vertebrae autograft seemed to be a new source of autogenous cortical bone in order to supporting segmental long bone defects in dogs. Furthermore, cellular autotransplantation was found to be a successful replacement for the tail vertebrae allograft bone at 3-4 cm segmental defects in the canine mid- ulna. Clinical application using graft expanders or bone autotransplantation should be used carefully and requires further investigation.

Energy-based guidance of an underactuated unmanned underwater vehicle on a helical trajectory

This paper presents a motion control system for guidance of an underactuated Unmanned Underwater Vehicle (UUV) on a helical trajectory. The control strategy is developed using Port-Hamiltonian theory and interconnection and damping assignment passivity-based control. Using energy routing, the trajectory of a virtual fully actuated plant is guided onto a vector field. A tracking controller is then used that commands the underactuated plant to follow the velocity of the virtual plant. An integral control is inserted between the two control layers, which adds robustness and disturbance rejection to the design.

Measuring attitudes in translation: a study of Nokia business reports

Background Contemporary Finnish, spoken and written, reveals loanwords or foreignisms in the form of hybrids: a mixture of Finnish and foreign syllables (alumiinivalua). Sometimes loanwords are inserted into the Finnish sentence in their raw form just as they are found in the source language (pulp, after sales palvelu). Again, sometimes loanwords are calques, which appear Finnish but are spelled and pronounced in an altogether foreign manner (Protomanageri, Promenadi kampuksella). Research Questions What role does Finnish business translation play in the migration of foreignisms into Finnish if we consider translation "as a construct of solutions determined by the ideological constraints and conflicts characterizing the target culture" (Robyns 1992: 212)? What attitudes do the Finns display toward the presence of foreignisms in their language? What socio-economic or ideological conditions (Bassnett 1994: 321) are responsible for these attitudes? Are these conditions dynamic? What tools can be used to measure such attitudes? This dissertation set out to answer these and similar questions. Attitudes are imperialist (where otherness is both denied and transformed), defensive (where otherness is acknowledged, transformed, and vilified), transdiscursive (a neutral attitude to both otherness and transformation), or finally defective (where alien migration is acknowledged and "stimulated") (Robyns 1994: 60). Methodology The research method follows Rose's schema (1984: 8): (a) take an existing theory, (b) develop from it a proposition specific enough to be tested, (c) devise a scheme that tests this proposition, (d) carry through the scheme in practice, (e) draw up results and discuss conclusions in relation to the original theory. In other words, the method attempts an explanation of a Finnish social phenomenon based on systematic analyses of translated evidence (Lewins 1992: 4) whereby what really matters is the logical sequence that connects the empirical data to the initial research questions raised above and, ultimately to its conclusion (Yin 1984: 29). Results This research found that Finnish translators of the Nokia annual reports used a foreignism whenever possible such as komponentin instead of rakenneosa, or investoida instead of sijoittaa, and often without any apparent justification (Pryce 2003: 203-12) more than the translator's personal preference. In the old documents (minutes of meetings of the Board of Directors of Osakeyhtio H. Saastamoinen, Ltd. dated 5 July 1912-1917, a NOPSA booklet (1932), Enzo-Gutzeit-Tornator Oy document (1938), Imatra Steel Oy Annual Report 1964, and Nokia Oy Annual Report 1946), foreignisms under Haugen's (1950: 210-31) Classification #1 occurred an average of 0.6 times, while in the new documents (Nokia 1998 translated Annual Reports) they occurred an average of 6.5 times. That big difference, suggests transdiscursive and defective attitudes in Finnish society toward the other. In the 1850s, Finnish attitudes toward alien persons and cultures were hardened, intolerant and prohibitive because language politics were both nascent and emerging, and Finns adopted a defensive stance (Paloposki 2002: 102 ff) to protect their cultural and national treasures such as language and folklore. Innovation The innovation here is that no prior doctoral level research measured Finnish attitudes toward foreignisms using a business translation approach. This is the first time that Haugen's classification has been modified and applied in target language analysis. It is hoped that this method would be replicated in similar research in the future. Applications For practical applications, researchers with interest in languages, language development, language influences, language ideologies, and power structures that affect national language policies will find this thesis useful, especially the model for collecting, grouping, and analyzing foreignisms that has been demonstrated here. It is intended to document for posterity current attitudes of Finns toward the other as revealed in business translations from 1912-1964, and in 1998. This way, future language researchers would be able to explore a time-line of Finnish language development and attitudes toward the other. Communication firms may also find this research interesting. In future, could the model we adopted be used to analyze literary texts or religious texts for example? Future Trends Though business documents show transdiscursive attitudes, other segments of Finnish society may show defensive or imperialist attitudes. When the ideology of industrialization changes in the future, will Finnish attitudes toward the other change as well? Will it then be possible to use the same kind of analytical tools to measure Finnish attitudes? More broadly, will linguistic change continue in the same direction of transdiscursive attitudes, or will the change slow down or even reverse into xenophobic attitudes? Is this our model culture-specific or can it be used in the context of other cultures? Conclusion There is anger against foreignisms in Finland as newspaper publications and television broadcasts show, but research shows that a majority of Finns consider foreignisms and the languages from which they come as sources of enrichment for Finnish culture (Laitinen 2000, Eurobarometer series 41 of July 1994, 44 of Spring 1996, 50 of Autumn 1998). Ideologies of industrialization and globalization in Finland have facilitated transdiscursive tendencies. When Finland's political ideology was intolerant toward foreign influences in the 1850s because Finland was in the process of consolidating her nascent country and language, attitudes toward the importation of loanwords also became intolerant. Presently, when industrialization and globalization became the dominant ideologies, we see a shift in attitudes toward transdiscursive tendencies. Ideology is usually unseen and too often ignored by translation researchers. However, ideology reveals itself as the most powerful factor affecting language attitudes in a target culture. Key words Finnish, Business Translation, Ideology, Foreignisms, Imperialist Attitudes, Defensive Attitudes, Transdiscursive Attitudes, Defective Attitudes, the Other, Old Documents, New Documents.

Heparin versus 0.9% sodium chloride intermittent flushing for the prevention of occlusion in long term central venous catheters in infants and children

Background Guidelines and clinical practice for the prevention of complications associated with central venous catheters (CVC) around the world vary greatly. Most institutions recommend the use of heparin to prevent occlusion, however there is debate regarding the need for heparin and evidence to suggest 0.9% sodium chloride (normal saline) may be as effective. The use of heparin is not without risk, may be unnecessary and is also associated with increased cost. Objectives To assess the clinical effects (benefits and harms) of intermittent flushing of heparin versus normal saline to prevent occlusion in long term central venous catheters in infants and children. Search Methods The Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (last searched April 2015) and the Cochrane Register of Studies (Issue 3, 2015). We also searched the reference lists of retrieved trials. Selection criteria Randomised controlled trials that compared the efficacy of normal saline with heparin to prevent occlusion of long term CVCs in infants and children aged up to 18 years of age were included. We excluded temporary CVCs and peripherally inserted central catheters (PICC). Data Collection and Analysis Two review authors independently assessed trial inclusion criteria, trial quality and extracted data. Rate ratios were calculated for two outcome measures - occlusion of the CVC and central line-associated blood stream infection. Other outcome measures included duration of catheter placement, inability to withdraw blood from the catheter, use of urokinase or recombinant tissue plasminogen, incidence of removal or re-insertion of the catheter, or both, and other CVC-related complications such as dislocation of CVCs, other CVC site infections and thrombosis. Main Results Three trials with a total of 245 participants were included in this review. The three trials directly compared the use of normal saline and heparin, however, between studies, all used different protocols for the standard and experimental arms with different concentrations of heparin and different frequency of flushes reported. In addition, not all studies reported on all outcomes. The quality of the evidence ranged from low to very low because there was no blinding, heterogeneity and inconsistency between studies was high and the confidence intervals were wide. CVC occlusion was assessed in all three trials (243 participants). We were able to pool the results of two trials for the outcomes of CVC occlusion and CVC-associated blood stream infection. The estimated rate ratio for CVC occlusion per 1000 catheter days between the normal saline and heparin group was 0.75 (95% CI 0.10 to 5.51, two studies, 229 participants, very low quality evidence). The estimated rate ratio for CVC-associated blood stream infection was 1.48 (95% CI 0.24 to 9.37, two studies, 231 participants; low quality evidence). The duration of catheter placement was reported to be similar between the two study arms, in one study (203 participants). Authors' Conclusions The review found that there was not enough evidence to determine the effects of intermittent flushing of heparin versus normal saline to prevent occlusion in long term central venous catheters in infants and children. Ultimately, if this evidence were available, the development of evidenced-based clinical practice guidelines and consistency of practice would be facilitated.

Identification and immunogenicity of an immunodominant mimotope of Avibacterium paragallinarum from a phage display peptide library

Avibacterium paragallinarum is the causative agent of infectious coryza. The protective antigens of this important pathogen have not yet been clearly identified. In this paper, we applied phage display technique to screen the immunodominant mimotopes of a serovar A strain of A. paragallinarum by using a random 12-peptide library, and evaluated the immunogenicity in chickens of the selected mimotope. Polyclonal antibody directed against A. paragallinarum strain 0083 (serovar A) was used as the target antibody and phage clones binding to this target were screened from the 12-mer random peptide library. More than 50% of the phage clones selected in the third round carried the consensus peptide motif sequence A-DP(M)L. The phage clones containing the peptide motif reacted with the target antibody and this interaction could be blocked, in a dose-dependent manner, by A. paragallinarum. One of the peptide sequences, YGLLAVDPLFKP, was selected and the corresponding oligonucleotide sequence was synthesized and then inserted into the expression vector pFliTrx. The recombinant plasmid was transferred into an expression host Escherichia coli GI826 by electroporation, resulting in a recombinant E. coli expressing the peptide on the bacterial surface. Intramuscular injection of the epitope-expressing recombinant bacteria into chickens induced a specific serological response to serovar A. A. paragallinarum. The chickens given the recombinant E. coli showed significant protection against challenge with A. paragallinarum 0083. These results indicated a potential for the use of the mimotope in the development of molecular vaccines for infectious coryza.

A Closed-Cycle Refrigerator Based Pulsed Management System

A low cost 12 T pulsed magnet system has been integrated with a closed-cycle helium refrigerator. The copper solenoid is directly immersed in liquid nitrogen for reduced electrical resistance and more efficient heat transfer. This ensures a minimal delay of few minutes between pulses. The sample is mounted on the cold finger of the refrigerator and, along with the surrounding vacuum shroud, is inserted into the bore of the solenoid. When combined with software lock-in signal processing to reduce noise, quick but accurate measurements can be performed at temperatures 4 K-300 K up to 12 T. Quantum Hall effect data in a p-channel SiGe/Si heterostructure has been used to calibrate the instrument against a commercial superconducting magnet. Its versatility as a routine characterization tool is demonstrated bymeasuring parallel conduction in Si/SiGe modulation doped heterostructures.

Chlorinated Hypoelectronic Dimetallaborane Clusters: Synthesis, Characterization, and Electronic Structures of (eta(5)-C5Me5W)(2)B5HnClm (n=7, m=2 and n=8, m=1)

Pyrolysis of (eta(5)-C5Me5WH3)B4H8, 1, in the presence of excess BHCl2 center dot SMe2 in toluene at 100 degrees C led to the isolation of (eta(5)-C5Me5W)(2)B5H9, 2, and B-Cl inserted (eta(5)-C5Me5W)(2)B5H8Cl, 3, and (eta(5)-C5Me5W)(2)B5H7Cl2, (four isomers). All the Chlorinated tungstaboranes were isolated as red and air and moisture sensitive solids. These new compounds have been characterized in solution by H-1, B-11, C-13 NMR, and the structural types were unequivocally established by crystallographic analysis of compounds 3, 4, and 7. Density functional theory (DFT) calculations were carded out on the model molecules of 3-7 to elucidate the actual electronic structures of these chlorinated species. On grounds of DFT calculations we demonstrated the role of transition metals, bridging hydrogens, and the effect of electrophilic substitution of hydrogens at B-H vertices of metallaborane structures.

Phosphine fumigation of silo bags.

Fumigation with phosphine has the potential to disinfest grain stored in silo bags but only limited research has been conducted on whether phosphine fumigation can be undertaken effectively and safely in this form of storage. Fumigation with phosphine was tested on two (70 m) replicate silo bags each containing 240 t of wheat (9.9 and 9.2% m.c.). The target application rate of phosphine was 1.5 g m 3 with a fumigation period of 17 days. Aluminium phosphide tablets were inserted into each bag at ten release points spaced at 7 m intervals starting 3.5 m from either end of the bag. A total of 14 bioassay cages containing mixed age populations of strongly phosphine resistant Rhyzopertha dominica (F.) were inserted into each fumigated silo bag. Complete control of all life stages of R. dominica was achieved at all locations in the fumigated silo bags. Phosphine concentrations at release points increased rapidly and remained high for the duration of the fumigation. Concentrations at midway points were always lower than at the release points but exceeded 215 ppm for ten days. The diffusion coefficient of available phosphine averaged over the first three full days of the fumigation for both fumigated silo bags was 2.8 x 10 7. Venting the silo bag with an aeration fan reduced the phosphine concentration by 99% after 12 h. Relatively small amounts of phosphine continued to desorb after the venting period. Although grain temperature at the core of the silo bags remained stable at 29degreesC for 17 days, grain at the surface of the silo bags fluctuated daily with a mean of 29degreesC. The results demonstrate that silo bags can be fumigated with phosphine for complete control of infestations of strongly phosphine resistant R. dominica and potentially other species.

Potato virus A as a heterologous protein expression tool in plants

Viruksien käyttö tuotekehityksen ja tutkimuksen vaatimien proteiinien tuottamiseen, syötävien rokotteiden kehittämiseen ja geeniterapiaan edustavat kasvavia biotekniikan sovellusalueita. Perunan A-virus (PVA) kuuluu potyviruksiin, joiden proteiinit tuotetaan aluksi yhtenä suurena molekyylinä, joka pilkotaan yksittäisiksi proteiineiksi viruksen itsensä tuottamilla entsyymeillä. Siten virusgenomiin lisätty vieras geeni käännetään proteiiniksi virusproteiinien mukana. Lopputuloksena kaikkia proteiineja tuotetaan kasvisoluissa samansuuruinen määrä. Lisäksi, viruksen proteiinikuoren koontimekanismi sallii perintöaineksen merkittävän lisäyksen ilman että viruksen tartutuskyky merkittävästi heikkenee. Koska virus monistuu ja leviää koko kasviin, jo melko pieni määrä kasveja riittää huomattavan proteiinimäärän tuottamiseen esimerkiksi säännösten mukaisessa kasvihuoneessa. Tämän työn tarkoituksena oli muuntaa PVA:n genomia siten, että virus soveltuisi yhden vieraan proteiinin tai useiden erilaisten proteiinien samanaikaiseen tuottamiseen kasveissa. Aluksi kokeiltiin viruksen replikaasia ja kuoriproteiinia koodaavien genomialueiden välistä kohtaa ja ihmisestä peräisi olevaa geeniä, joka tuotti S-COMT-entsyymiä (katekoli-O-metyylitransferaasi). Sen aktiivisuuden rajoittaminen auttaa Parkinsonintaudin hoidossa. Kasvissa tuotettua S-COMT:ia voitaisiin käyttää lääkekehityksessä estolääkkeiden testaukseen. Kahden viikon kuluttua tartutuksesta tupakan lehdissä oli entsymaattisesti aktiivista S-COMT:ia n. 1 % lehden liukoisista proteiineista. PVA:n P1-proteiinia koodaavalta alueelta oli paikannettu kohta, johon ehkä voitaisiin siirtää vieras geeni. Asia varmistettiin siirtämällä tähän kohtaan meduusan geeni, joka tuottaa UV-valossa vihreänä fluoresoivaa proteiinia (GFP). GFP-geeniä kantava PVA levisi kasvissa ja lisääntyi n. 30-50 %:iin viruksen normaalista pitoisuudesta. Koko kasvi fluoresoi vihreänä UV-valossa. Vieras geeni voidaan sijoittaa myös potyviruksen P1- ja HCpro-proteiineja koodaavien alueiden väliin. Samaan PVA-genomiin siirrettiin kolme geeniä, yksi kuhunkin kolmesta kloonauskohdasta: GFP-geeni P1:n sisälle, merivuokon lusiferaasigeeni P1/HCpro-kohtaan ja bakteerin beta-glukuronidaasigeeni (GUS) replikaasi/kuoriproteiini-kohtaan. Virusgenomin ja itse viruksen pituudet kasvoivat 38 %, mutta virus säilytti tartutuskykynsä. Se levisi kasveissa saavuttaen n. 15 % viruksen normaalista pitoisuudesta. Kaikki kolme vierasta proteiinia esiintyivät lehdissä aktiivisina.

Lactic acid bacteria and their antimicrobial peptides : Induction,detection,partial characterization, and potential applications

Bacteriocin-producing lactic acid bacteria and their isolated peptide bacteriocins are of value to control pathogens and spoiling microorganisms in foods and feed. Nisin is the only bacteriocin that is commonly accepted as a food preservative and has a broad spectrum of activity against Gram-positive organisms including spore forming bacteria. In this study nisin induction was studied from two perspectives, induction from inside of the cell and selection of nisin inducible strains with increased nisin induction sensitivity. The results showed that a mutation in the nisin precursor transporter NisT rendered L. lactis incapable of nisin secretion and lead to nisin accumulation inside the cells. Intracellular proteolytic activity could cleave the N-terminal leader peptide of nisin precursor, resulting in active nisin in the cells. Using a nisin sensitive GFP bioassay it could be shown, that the active intracellular nisin could function as an inducer without any detectable release from the cells. The results suggested that nisin can be inserted into the cytoplasmic membrane from inside the cell and activate NisK. This model of two-component regulation may be a general mechanism of how amphiphilic signals activate the histidine kinase sensor and would represent a novel way for a signal transduction pathway to recognize its signal. In addition, nisin induction was studied through the isolation of natural mutants of the GFPuv nisin bioassay strain L. lactis LAC275 using fl uorescence-activated cell sorting (FACS). The isolated mutant strains represent second generation of GFPuv bioassay strains which can allow the detection of nisin at lower levels. The applied aspect of this thesis was focused on the potential of bacteriocins in chicken farming. One aim was to study nisin as a potential growth promoter in chicken feed. Therefore, the lactic acid bacteria of chicken crop and the nisin sensitivity of the isolated strains were tested. It was found that in the crop Lactobacillus reuteri, L. salivarius and L. crispatus were the dominating bacteria and variation in nisin resistance level of these strains was found. This suggested that nisin may be used as growth promoter without wiping out the dominating bacterial species in the crop. As the isolated lactobacilli may serve as bacteria promoting chicken health or reducing zoonoosis and bacteriocin production is one property associated with probiotics, the isolated strains were screened for bacteriocin activity against the pathogen Campylobacter jejuni. The results showed that many of the isolated L. salivarius strains could inhibit the growth of C. jejuni. The bacteriocin of the L. salivarius LAB47 strain, with the strongest activity, was further characterized. Salivaricin 47 is heat-stable and active in pH range 3 to 8, and the molecular mass was estimated to be approximately 3.2 kDa based on tricine SDS-PAGE analysis.