Doctoral Thesis
Refine
Year of publication
- 2016 (46) (remove)
Document Type
- Doctoral Thesis (46) (remove)
Language
- English (46) (remove)
Has Fulltext
- yes (46)
Is part of the Bibliography
- no (46)
Keywords
- Genetik (3)
- Atmosphärendruckplasma (2)
- Biokatalyse (2)
- Enzyme (2)
- Molecular biology (2)
- Molekularbiologie (2)
- Plasmadiagnostik (2)
- Plasmamedizin (2)
- Plasmaphysik (2)
- Protein-Engineering (2)
Institute
- Institut für Physik (8)
- Institut für Biochemie (7)
- Abteilung für Mikrobiologie und Molekularbiologie (4)
- Institut für Botanik und Landschaftsökologie & Botanischer Garten (3)
- Institut für Mathematik und Informatik (3)
- Institut für Geographie und Geologie (2)
- Institut für Immunologie u. Transfusionsmedizin - Abteilung Immunologie (2)
- Institut für Immunologie u. Transfusionsmedizin - Abteilung Transfusionsmedizin (2)
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung (UMG) (2)
- Poliklinik für Kieferorthopädie, Präventive Zahnmedizin und Kinderzahnheilkunde (2)
This thesis deals with thickness optimization of shells. The overall task is to find an optimal thickness distribution in order to minimize the deformation of a loaded shell with prescribed volume. In addition, lower and upper bounds for the thickness are given. The shell is made of elastic, isotropic, homogeneous material. The deformation is modeled using equations from Linear Elasticity. Here, a basic shell model based on the Reissner-Mindlin assumption is used. Both the stationary and the dynamic case are considered. The continuity and the Gâteaux-differentiability of the control-to-state operator is investigated. These results are applied to the reduced objective with help of adjoint theory. In addition, techniques from shape optimization are compared to the optimal control approach. In the following, the theoretical results are applied to cylindrical shells and an efficient numerical implementation is presented. Finally, numerical results are shown and analyzed for different examples.
In this work the mechanisms leading to the generation of the various reactive oxygen and nitrogen species (RONS) in a cold atmospheric plasma (CAP) jet and means to control their composition were studied. The investigated CAP jet kinpen is typically operated with Ar feed gas (pure or with molecular admixtures), driven at a frequency of approximately 1 MHz and features fast ionization waves or guided streamers, traveling at velocities of several km/s. The complex reaction networks were investigated by numerical and experimental techniques. Detailed experimental, analytical and computational investigations on the mass and heat transport in the plasma plume were performed: A novel analytical approach to diffusion in jet flows, the non-dispersive path mapping approximation (NDPM) was developed. The method for the first time allows for an estimation of the ambient species density in the near-field of jets that feature a non-homogeneous flow-field. The NDPM approximation was employed for the evaluation of laser induced fluorescence measurements on OH. Through combining measurements and NDPM approximation, this approach yielded an estimation for the ambient species density at the position of the guided streamers, not only in the laminar, but also in the (standard) turbulent operating regime. Accurate measurements of the temporally averaged ambient species density and temperature in the plasma plume were obtained by quantitative Schlieren measurements. The method yields temperature values with sub-Kelvin accuracy and, through combination with computational fluid dynamics (CFD) simulations, allowed for an estimation of the calorimetric power of the jet. In order to obtain a defined environment for the jet to operate in, a shielding gas device was designed in this work, which creates a gas curtain of defined composition around the plasma plume. The plasma dynamics on the ns timescale was investigated by phase resolved optical measurements. The effect of different shielding compositions ranging from pure N2 to pure O2 on guided streamer propagation was investigated. An electrostatic focusing mechanisms was discovered, which promotes the propagation of guided streamers along the channels formed by a noble gas in the plume of plasma jets operating in electronegative gases (such as air or O2). Two zero-dimensional (volume averaged) models were developed: First, the local processes in the guided streamer were modeled using an electron impact reaction kinetic model, which is closely correlated to densities of metastable argon (Ar*) obtained by laser atom absorption measurements. This first model shows that Ar* is the species which dominantly drives the plasma chemistry in the plasma plume. This is exploited in the second plug-flow reaction kinetics model, which is employed to investigate the formation of long-living RONS and uses an Ar* source term as sole energy input. The model uses the previous experimental data on mass and heat transport and temporal dynamics as input and is in turn verified by quantitative FTIR absorption measurements on O3, NO2, N2O, HNO3 and N2O5 in the far-field of the jet, where large absorption lengths can be achieved using a multi pass cell. For the evaluation of the zero-dimensional model, the time-of-flight of RONS from their generation to reaching the multi pass cell was determined using CFD simulations. The insight gained through this combined experimental-modeling approach on the reaction networks revealed relevant control parameters and enabled adjusting the plasma chemistry towards a desired RONS output. Through choosing appropriate feed-gas admixtures and shielding gas compositions, it is possible to generate an NOx-dominated plasma chemistry, although the jet usually produces a strongly O/O3-dominated chemistry. Understanding and controlling the plasma chemistry of cold atmospheric plasma sources for medical applications is not only essential for research, but is also the key for designing future plasma sources for specific medical applications that yield an optimum efficacy and avoid potential side effects of plasma treatment.
Background: Referral to specialized pediatric treatment seems to rise in Germany, especially for children under 5 years of age and mostly due to behaviour management problems, rampant caries and the need for comprehensive dental treatments. There are indications that more dental treatments under general anesthesia were needed in last decade, but there are very few studies on this topic in Germany. Aim: The objectives of this research were to investigate the characteristics and dental features of referred children to Greifswald university dental clinic in 2008 and 2011 as well as to assess dental treatment and characteristics of the children who underwent general anesthesia in 2011 at Greifswald University Clinic in comparison with three specialized pediatric private practices in Germany. Materials and methods: This retrospective analytical comparative study examined the records of all children younger than 18 years of age, whose were referred to the university dental clinic in Greifswald between 2008 and 2011. In addition, all cases that underwent general anesthesia at the university dental clinic and three other private practices in 2011 were analyzed anonymously. All data including age, gender, dental status and caries levels (dmft/DMFT), as well as diagnosis, referral/GA reasons and the dental treatments were collected and then analyzed using the Statistical Package for the Social Sciences program (SPSS, Ver. 16 for Windows). Descriptive analysis was performed, along with univariate analysis of variance (ANOVA) and Chi square tests. Differences between groups were tested through Mann-Whitney U test and Student’s t-test as appropriate. Results: The final study sample for children and adolescents referred to the university consisted of 389 under 18 years old (205 males and 184 females) with a mean age of 8.75 years in 2008 and 7.38 years in 2011. In addition, 297 children (160 males and 137 females) with a mean age of 4.77 years had been treated under general anesthesia in the three specialized private practices (n= 219, age: 4.81±2.06 years) and in the university (n=78, age: 4.65±2.59 years). More patients of age group 1 (5 yrs or younger), as well as, patients residing within a distance of 31-40 km away from the clinic were referred in 2011 (47.2% and 35.9% resp.) in comparison with 2008 (37.1% and 22.7% resp.) Panoramic and intraoral dental x-rays (46.7%, 11.8% resp.) have been widely carried out in 2011 compared to 2008 (29.9%, 6.5% resp. P = 0.002). Statistical analyses have shown that, younger children with higher values of dental caries indices (dmft, DMFT) were referred in 2011 (5.4 and 2.15 resp.) than in 2008 (5.16 and 1.57 resp.) with increasing demand for comprehensive dental treatment under GA. Whereas, more patients were diagnosed to have rampant caries (42.1%) in 2011 followed by orthodontic/oral surgery problems (16.9%) in comparison with 2008 (29.3%, 10.1% resp. P < 0.001). Non-invasive treatment was much more delivered (63%) in first dental visit for referred patients in 2011 followed by dental consultation (23.6%) compared to 2008 (53.6% and 21.3% resp.). While, on the other hand, considerably more fillings were supplied in 2008 (11.5%) compared to 2011 (2.6%). Further dental treatment pattern revealed more treatment under GA (27%) and a slightly more extractions (16.1%) were done in 2011 compared to 2008 (20.9%, 15.5% resp.). On the contrary, less fillings and preventive procedures were performed in 2011 (26.3% and 4.4% resp.) in comparison with 2008. Sixty-one percent of children were referred back to their family dentists in 2011 which was more than it in 2008. Indeed, about a half of children aged 5 years or younger preferred to stay at the University Clinics in 2011, while, the vast majority of children older than 12 years continued their dental care outside the University Clinics. About eighty percent and seventy percent of children underwent GA at both the university clinics and private practices respectively were under five years old. In total 7.1% mental disabilities and 2.4% preterm birth were detected in children treated under GA, as well as, dental caries were mostly diagnosed (37%) among them followed by irreversible pulpitis (21.5%) and Early Childhood Caries (ECC) (18.5%), where only 4.38% of all examined children had no carious lesions. More panoramic radiographs (41%) and less dental films (26.9%) were conducted at the university clinics as in the private practices (15.1% and 52.1% respectively) with a significant reduction in using x-rays at the university (69.2%) compared to private practices (94.1%). Dental extractions were often performed at university clinic (40.2%, 3.14±2.4) followed by fillings (33.9%, 2.65±2.7), while, more restorations and less extractions were supplied at private practices (47.8%, 5.47±3.1 and 16.3%, 1.86±2 resp.). Both of long (106-120 Min) and short (0-15 Min) treatment’s durations were needed in the university clinics to carried out the adequate dental therapy under GA, while, most of the GAs at private practices have lasted between 45 and 90 minutes. Conclusion: There is a growing definite need for specialized pediatric dentistry in Germany, especially for children under 5 years of age being referred with rampant caries and behaviour management problems to specialized pediatric dentistry. This results in a high number of extensive treatment performed under GA. In contrast to other countries, this seems to be a singular event for most children in Germany indicating a solid treatment under GA and possibly also improvements in the caries activity of the affected children afterwards. The range of dental treatment and its outcome at Greifswald University and in the examined three specialized private practices is very similar reflecting in both the profile of the children a valid indication for GA and the subsequent treatment up to date approaches in pediatric dentistry. Thus, the very professional treatment and effective secondary preventive strategies achieve better oral health and reestablished quality of life for these children, but a primary preventive approach would be preferable decreasing the number of children in need of dental treatment under general anaesthesia.
The aim of this retrospective observational study is to describe and discuss various complications that can arise after insertion of alloplastic materials in the field of urogynecology that require further surgical interventions in order to manage them or to at least improve the quality of life in those women. We were able to collect data on 77 patients who fulfilled the criteria. Medical history, data of clinical findings, and outcomes were collected and analyzed. The most common complication seen as an indication for resecting slings or meshes was de novo overactive bladder syndrome (40%). Other indications seen were lower urinary tract obstruction or obstructive voiding symptoms (21%), chronic pain (21%), and de novo dyspareunia (13%). 36% of the patients had recurrent symptoms (failure) after insertion of alloplastic materials in the form of urinary incontinence or prolapse, 32% presented with vaginal erosions, 2 women had severe signs of infection with abscess formation, another 3 women had urogenital fistulae. Other rare complications after mesh or sling insertion are perforations of the urinary bladder or urethra. Proper case selection is the key factor. The use of meshes and slings seems justified only in patients with known connective tissue weakness and recurrences after native tissue repair. Otherwise, patients will be exposed to unnecessary risk without any expectable improvement to their quality of life. Most of the complications are mainly caused by wrong and inadequate surgical techniques, wrong indications, or missed diagnosis of the underlying problem. In addition, lack of long-term follow-up is usually the cause behind the negligence towards many complications. Therefore, only experienced physicians should be allowed to perform such procedures, and long-term postoperative follow-up is strongly recommended. As slings and meshes are used for procedures of choice as means to improve quality of life, and not for life threatening situations, there is a need for intensive informed consent. All possible alternatives have to be discussed, as do the pros and cons of selected procedures, even the rare complications. Mesh or sling resection is considered to be an effective solution for the management of such complications. It has shown a high success rate in comparison to conservative treatment, and the majority of patients were satisfied and experienced a big improvement in their quality of life. The most common complication after resection is the recurrence of primary symptoms, either urinary incontinence or prolapse. Major or serious intra- or postoperative complications are very rare. All complications were classified and given a code according to the classification system of the international urogynecological association and the international continence society (IUGA/ICS) on 2011. The applicability and practicability of this code were evaluated, looking for ways to possibly improve it or to identify missing parameters. Many patients had more than one code, a problem that entirely torpedoed the idea of “simple” classification. Some complications are not covered individually in the classification, such as failure and recurrence or overactive bladder syndrome. These complications should be included. Many cases began with the same code, despite having different complications. Further sub-classifications should be considered to enable the reader to easily recognize the complication at hand. Patients who came with complications more than one year after mesh or sling insertion were categorized as (T4), regardless of whether the complication arose after 1 year of after 10. Therefore, sub-classifications in the (T4) category are recommended. The “site” category was not applicable in many cases. Furthermore, it is necessary that the severity of a complication is discernible, and should be mentioned in the code. We did not find any correlation between the code given and patient satisfaction. After re-modification and completion, the IUGA/ICS code could be more practical for clinical use, which would allow for the comparison of complications and make the assessment of adverse effects easier for research purposes.
Alcohol dehydrogenases as biocatalysts for the production of enantiomerically pure chiral alcohols
(2016)
Summary Enantiomerically pure chiral alcohols are key compounds in the production of certain chemicals including pharmaceuticals. Chemical synthesis allows to obtain maximal yield of 50% for one enantiomer ( >50% yield is achievable with chiral catalysts used in chemical synthesis), whereas biosynthesis leads to nearly 100% yield. Hence, expensive and time consuming resolution of racemic mixture can be avoided. Alcohol dehydrogenases are the most popular enzymes used in the chiral alcohols synthesis due to high activity with appropriate aldehydes or ketones. ADHs require a cofactor which has to be regenerated after the conversion of aldehyde/ketone to the respective alcohol. Thereby, different regeneration methods were used in the practical work to compare and choose the better one. R. erythropolis and C. hydrogenoformans alcohol dehydrogenases were chosen based on the literature screening. Each gene was cloned into Xplor2 vector and pFPMT vector. Xplor2 vector was used for the transformation of A. adeninivorans and pFPMT vector was used for the transformation of H. polymorpha. Chemically synthesized alcohol dehydrogenase sequences from R. erythropolis (ReADH) and C. hydrogenoformans (ChADH) were cloned between TEF1 promoter and PHO5 terminator which are components of Xplor2 vector or between FMD promoter and MOX terminator which are genetic elements of pFPMT vector. Moreover, ChADH and ReADH sequences with His-tag encoding sequence at the 5’ or 3’ end were constructed and the most active form of the protein was selected for further studies. ReADH-6H was used for the synthesis of 1-(S)-phenylethanol and ethyl (R)-4-chloro-3-hydroxybutanoate whereas ChADH-6H was used for the production of ethyl (R)-mandelate. ReADH-6H synthesized in A. adeninivorans and H. polymorpha was fully biochemically characterized. The enzymes from the two yeast species showed some differences in their pH and temperature optima, thermostability and activity levels. A-ReADH (A. adeninivorans) and H-ReADH (H. polymorpha) were highly active with the same substrates which were: acetophenone, 4-hydroxy-3-butanone and ethyl 4-chloroacetoacetate for reduction reaction along with 1-phenylethanol and 1,6-hexanediol for oxidation reaction. Recombinant A-ReADH-6H and H-ReADH-6H were synthesized in A. adeninivorans and H. polymorpha, respectively. Both enzymes were used for the synthesis of 1-(S)-phenylethanol and ethyl (R)-4-chloro-3-hydroxybutanoate with the use of substrate-coupled cofactor regeneration system. The enantiopurity of the products was >99%. Moreover, A. adeninivorans whole cell catalyst was also used for the synthesis of both chiral alcohols. BmGDH (Bacillus megaterium glucose dehydrogenase) was co-expressed with ReADH-6H for NADH cofactor regeneration. Comparison between isolated enzymes and permeabilized whole cell catalysts indicate that cell biocatalysts are more suitable for the production of 1-(S)-phenylethanol with 92% of acetophenone being converted in 60 min. However, cells did not show any significant advantage over isolated enzymes in the synthesis of ethyl (R)-4-chloro-3-hydroxybutanoate although the velocity of the synthesis of ethyl (R)-4-chloro-3-hydroxybutanoate was slightly improved using whole-cell catalysts, giving an 80% substrate conversion in 120 min. Recombinant C. hydrogenoformans alcohol dehydrogenase was synthesized in A. adeninivorans and biochemically characterized. Enzyme showed high activity only with one substrate, ethyl benzoylformate. The A. adeninivorans and H. polymorpha cell catalysts synthesizing ChADH and BmGDH (Bacillus megaterium glucose dehydrogenase) were constructed and used in the synthesis of ethyl (R)-mandelate (reduction product of ethyl benzoylformate) with the enantiopurity of the reaction product being >98%. H. polymorpha catalysts were more effective in the synthesis than A. adeninivorans cells. The first were able to convert 93% of ethyl benzoylformate within 180 min and the latter were converting 94% of the substrate within 360 min. Re-use of non-immobilized cells and catalysts entrapped in Lentikat® was performed and the improvement of the stability of immobilized catalysts was reported. Space time yield of 3.07 mmol l-1 h-1 and 6.07 mmol l-1 h-1 was achieved with A. adeninivorans and H. polymorpha cell catalysts, respectively. Alcohol dehydrogenase 1 from A. adeninivorans was analyzed concerning the synthesis of enantiomerically pure chiral alcohols. The enzyme did not synthesize industrially attractive products. However, based on biochemical characterization enzyme plays a role in the synthesis of 1-butanol or ethanol and thereby it is of biotechnological interest.
The presented study was dedicated to outstanding issues in regard to the safety and efficacy of the LAV “CP7_E2alf”, during the final licensing process and towards its putative implementation in outbreak scenarios as emergency vaccine. (I) For application of a genetically engineered virus under field conditions, knowledge about its genetic stability is mandatory. Therefore, the genetic stability of “CP7_E2alf” needed to be assessed in vivo and in vitro. Mutation rates were compared to the parental pestivirus strains (BVDV-1 “CP7” and CSFV “Alfort/187”), and BVDV or CSFV field-strains. There was no indication that “CP7_E2alf” could be more prone to mutational events than its parental viruses or representative field-strains. Moreover, no recombination events were observed in in vitro experiments. In conclusion, the data obtained in this study confirm a strong genetic stability of “CP7_E2alf” as an important safety component. (II) Since vaccination of breeding animals is often discussed, this study was conducted to assess the safety of “CP7_E2alf” vaccination of breeding male pigs. The study with “CP7_E2alf” vaccinated boar demonstrated that the new CSFV marker vaccine is suitable for application in reproductive boar. Neither in organs of the uro-genital tract related to sperm production nor in urine or feces, vaccine virus genome was detectable. Dissemination of “CP7_E2alf” through semen, and shedding with urine and feces, is therefore highly unlikely. (III) In order to investigate the influence of pre-existing pestivirus antibodies of the efficacy of “CP7_E2alf”, a vaccination-challenge-trial was conducted with “CP7_E2alf” (Suvaxyn® CSF Marker) and the “gold-standard” of live-modified CSFV vaccines, the C-strain (RIEMSER® Schweinepestvakzine). Pre-existing antibodies against BVDV-1 were provoked through intramuscular inoculation of a recent field isolate from Germany. Seven days after the vaccination, all animals were challenged with highly virulent CSFV strain “Koslov”. It was demonstrated that pre-existing anti- BVDV-1 antibodies do not impact the efficacy of both live attenuated vaccines against CSFV. Both C-strain “Riems” and marker vaccine “CP7_E2alf” were able to confer full protection against the highly virulent challenge. However, slight interference was seen with serological DIVA diagnostics accompanying “CP7_E2alf”. Amended sample preparation and combination of test systems was able to resolve most cases of false positive reactions. However, in such a coinfection scenario, optimization and embedding in a well-defined surveillance strategy is clearly needed for marker vaccination scenarios. (IV) To supplement the data about the kinetic of maternally derived antibodies in piglets from sows vaccinated during outbreaks, a single “emergency-type” vaccination of two pregnant sows was done. Focus was laid on the kinetics of maternally derived antibodies (MDA) in the screening assays of their offspring with screening assays that would be used in case of CSFV outbreaks, i.e. CSFV E2 and Erns antibody ELISA. Upon vaccination with “CP7_E2alf” 21 days before farrowing, MDAs were measurable in all piglets born to vaccinated sows. The E2- ELISA reactivities showed an almost linear decrease over ten weeks after which all piglets were tested negative in the ELISA. Future studies should investigate, if MDA are able to protect offspring of vaccinated sows or whether the piglets should also be vaccinated.
The history of Mathematics has been lead in part by the desire for generalization: once an object was given and had been understood, there was the desire to find a more general version of it, to fit it into a broader framework. Noncommutative Mathematics fits into this description, as its interests are objects analoguous to vector spaces, or probability spaces, etc., but without the commonsense interpretation that those latter objects possess. Indeed, a space can be described by its points, but also and equivalently, by the set of functions on this space. This set is actually a commutative algebra, sometimes equipped with some more structure: *-algebra, C*-algebra, von Neumann algebras, Hopf algebras, etc. The idea that lies at the basis of noncommutative Mathematics is to replace such algebras by algebras that are not necessarily commutative any more and to interpret them as "algebras of functions on noncommutative spaces". Of course, these spaces do not exist independently from their defining algebras, but facts show that a lot of the results holding in (classical) probability or (classical) group theory can be extended to their noncommutative counterparts, or find therein powerful analogues. The extensions of group theory into the realm of noncommutative Mathematics has long been studied and has yielded the various quantum groups. The easiest version of them, the compact quantum groups, consist of C*-algebras equipped with a *-homomorphism &Delta with values in the tensor product of the algebra with itself and verifying some coassociativity condition. It is also required that the compact quantum group verifies what is known as quantum cancellation property. It can be shown that (classical) compact groups are indeed a particular case of compact quantum groups. The area of compact quantum groups, and of quantum groups at large, is a fruitful area of research. Nevertheless, another generalization of group theory could be envisioned, namely by taking a comultiplication &Delta taking values not in the tensor product but rather in the free product (in the category of unital *-algebras). This leads to the theory of dual groups in the sense of Voiculescu, also called H-algebras by Zhang. These objects have not been so thoroughly studied as their quantum counterparts. It is true that they are not so flexible and that we therefore do not know many examples of them and showing that some relations cannot exist in the dual group case because they do not pass the coproduct. Nevertheless, I have been interested during a great part of my PhD work by these objects and I have made some progress towards their understanding, especially regarding quantum Lévy processes defined on them and Haar states.
Hantaviruses are enveloped viruses with a single-stranded RNA genome of negative polarity. The genome consists of three segments: small (S), medium (M) and large (L). As zoonotic pathogen, hantaviruses are worldwide responsible for 150,000 to 200,000 human disease cases per year. Two forms of human disease are currently distinguished: In the Americas the hantavirus cardiopulmonary syndrome (HCPS) and in Europe and Asia the hemorrhagic fever with renal syndrome (HFRS). Since the introduction of the German Protection against Infection Act in 2001 until now a total of 10,082 disease cases have been reported. As a result, hantavirus infections currently rank as the fifth frequent notifiable disease in Germany. More than 80% of these infections were caused by the hantavirus species Puumala virus (PUUV), transmitted by the bank vole Myodes glareolus. Besides temporal oscillations, an unequal geographical distribution of human PUUV cases was noticed in Germany and in other countries of Central Europe. This is reflected in the presence of endemic and non-endemic regions as well as of so-called outbreak years. Therefore, the overall objective of this study was to find out possible reasons for the inhomogeneous distribution of PUUV in Central Europe, in particular in Poland, Germany and certain districts of Baden-Wuerttemberg. The basic working hypothesis was that PUUV spread in Central Europe after the last glaciation with different evolutionary lineages of the bank vole and that the current emergence of PUUV in bank vole populations is determined by local geographical and ecological factors. Very little was known about the presence of PUUV in Poland. Earlier studies were based exclusively on serological detection of PUUV, but a molecular detection with subsequent phylogenetic investigation was missing so far. Therefore, 45 bank voles from the northeastern part of Poland were investigated by serological and molecular assays. In three animals from a forest region close to the city of Miko³ajki PUUV-reactive antibodies and/or PUUV RNA were detected. Phylogenetic analysis indicated the presence of a Latvian (LAT) PUUV strain. Viral RNA was detected in one bank vole of the Eastern evolutionary lineage and two animals of the Carpathian lineage. Thereby it could be demonstrated for the first time that the distribution of the LAT PUUV lineage ranges from Latvia south-west to the northeastern part of Poland. An inhomogeneous spatial distribution of human disease cases has been observed even for Baden-Wuerttemberg, a long time known endemic federal state of Germany. Therefore 660 bank voles were trapped during the outbreak and non-outbreak years 2012 and 2013 in four districts with high incidences (H) and in four districts with low incidences or lacking PUUV cases (L). During the outbreak year 2012 PUUV-positive bank voles were detected by serological and molecular investigations in seven of eight districts. In contrast, in the following year only in one district PUUV infected bank voles were detected. Furthermore, it was demonstrated that after a beech mast, i.e., a massive fructification of beech trees, in H districts with a higher percentage of beech forest coverage a higher number of human cases was notified, but not in L districts with a lower percentage of beech forest coverage. For the future development of early warning modules it is therefore necessary to have a long-term bank vole monitoring established that incorporates beech mast data and information on beech forest coverage. High endemic regions for PUUV are mainly located in the southern and western parts of Germany, whereas in the eastern and northern parts only low numbers or even no human cases are recorded. To find out possible reasons for this inhomogeneous distribution, 1,774 bank voles from different regions of Germany were investigated for PUUV infections and in parallel for the corresponding bank vole evolutionary lineage (Western, Eastern, Carpathian). The PUUV investigations indicated positive voles in the known endemic regions with an easternmost and northernmost occurrence in western Saxony-Anhalt, western Thuringia and in Osnabrück. In the northern and eastern part of Germany none of the 1,210 investigated bank voles showed a PUUV infection. In the southern and western parts of Germany only the Western bank vole lineage was identified, whereas the Eastern lineage was exclusively found in the eastern and northern part and the Carpathian lineage in the South-East and North-East of Germany. PUUV infections were found almost exclusively in bank voles of the Western lineage. Individuals of the other two vole lineages were found to be PUUV infected only in regions with sympatric occurrence of the Western lineage. The previously described contact zone of the different bank vole phylogroups ranges from Poland to the entire northern part of Germany. In conclusion, the results of this investigation indicate two potential major reasons for the inhomogeneous distribution of PUUV in Germany: First, PUUV of the CE lineage seems to be associated with the Western bank vole lineage. The current geographical distribution of virus and host might be explained by a post-glacial northern expansion of the bank vole starting at the western refuge. Second, the missing detection of PUUV in bank voles of the Western lineage in areas close to high endemic regions might be explained by the extinction of the virus due to a limited winter survival of infected animals during long and harsh winters. The virus stability outside the host or ecological barriers, such as isolated forest areas or broad rivers, might also influence the distribution of PUUV in bank vole populations.
Generally, all works dealt primarily with the biodiversity and phylogeny of leaf-inhabiting fungi of three Ficus species (F. benjamina, F. elastica and F. religiosa) with the exception of the bioprospecting which focused on discovering antimicrobial activities and secondary metabolite production. Investigations took place in natural and urban forests in the Philippines and in tropical greenhouse gardens in Germany.
Destination Image, Tourist Satisfaction and Destination Loyalty: A Case Study of Hue, Vietnam
(2016)
Several studies have confirmed the interrelationship among destination image, tourist satisfaction and destination loyalty, in which destination image and tourist satisfaction are believed to have great influences on the destination loyalty of tourists. Located in the central region of Vietnam, Hue holds great potential for tourism development and this destination has also obtained numerous significant tourism achievements over recent years.Nevertheless, there are still a lot of issues needed to be addressed by the destination managers in order to make Hue gain a better position and higher level of destination loyalty in the tourism market, in which successfully communicating an attractive destination image to the tourists and improving their satisfaction are the most important tasks. In fact, there exist very few researches concerning destination image, tourist satisfaction or even destination loyalty which have been done in Hue. Moreover, most of these studies are in very small scale and they only examine either the destination image or the tourist satisfaction or the destination loyalty independently. This paper, therefore, aims to deliver the first and comprehensive theoretical and empirical analysis of destination image, tourist satisfaction and destination loyalty as well as the causal relationship among them in the context of Hue. In this study, a destination loyalty research model was proposed and hypotheses were derived. The empirical data base on two tourist surveys with a total number of 2042 questionnaires collected in Hue in 2013 and 2014. In addition, ten experts were interviewed in different periods during the study. The results find that the tourists’ perceptions on the destination image of Hue are quite positive and the positive level is higher for those who completely have no earlier experience in Hue. It is also discovered that the destination is offering tourists with a pretty satisfactory experience, not as high as their initial expectations, but acceptable with positive ratings received from the tourists. However, if the destination is able to better communicate a positive image to tourists and improves the quality of its offers and services, the tourists’ satisfaction will be increased and thus the destination loyalty will also be enhanced. This finding supports the proposed destination loyalty model: (1) destination image directly influences attribute-satisfaction; (2) destination image and attribute-satisfaction are both direct influences of overall-satisfaction; and (3) overall-satisfaction in turn has a direct and positive impact on destination loyalty. The findings also confirm that attribute-satisfaction and destination image are also the direct influences of destination loyalty. Furthermore, the results add to the proposed loyalty model a new relationship: Destination image is influenced strongly by tourist overall-satisfaction and attribute-satisfaction. The outcomes of this research are expected to be used as a valuable reference for the local policy-makers, governmental agencies, tourism companies and other relevant stakeholders. Also, important theoretical and managerial implications are drawn based on the study findings and the recommendations for future researchers are made from the limitations and scopes of the study.