Artificial Interferences Research Articles

Dynamic wave propagation in infinite saturated porous media half spaces

From a macroscopic perspective, saturated porous materials like soils represent volumetrically interacting solid---fluid aggregates. They can be properly modelled using continuum porous media theories accounting for both solid-matrix deformation and pore-fluid flow. The dynamic excitation of such multi-phase materials gives rise to different types of travelling waves, where it is of common interest to adequately describe their propagation through unbounded domains. This poses challenges for the numerical treatment and demands special solution strategies that avoid artificial and numerically-induced perturbations or interferences. The present paper is concerned with the accurate and stable numerical solution of dynamic wave propagation problems in infinite half spaces. Proceeding from an isothermal, biphasic, linear poroelasticity model with incompressible constituents, finite elements are used to discretise the near field and infinite elements to approximate the far field. The transient propagation of the poroacoustic body waves to the infinity is thereby modelled by a viscous damping boundary, which, for stability reasons, necessitates an appropriate treatment of the included velocity-dependent damping forces.

The Performance of a Dual Header Pulse Interval Modulation in the Presence of Artificial Light Interferences in an Indoor Optical Wireless Communications Channel with Wavelet Denoising

Problem statement: Similar to other baseband modulation schemes, the performance of the Dual Header Pulse Interval Modulation (DH-PIM) is adversely affected by Artificial Light Interferences (ALI) in an indoor Optical Wireless Communications (OWC) channel. Approach: The Discrete Wavelet Transform (DWT) based denoising is studied for reducing the effect of the ALI. Computer simulation is carried out to demonstrate the effectiveness of the proposed system. The Baseline Wander (BLW) affects for a range of bit resolutions is also analyzed. Results: The normalized optical power requirement in the presence of ALI is high in the range of 9-15 dB depending upon the bit resolution. A significant reduction in the optical power penalty is observed with the DWT denoising scheme. Conclusion: The DWT based denoising scheme is effective in reducing the consequence of the ALI. The optical power penalty decreases with an increase in the data rate and the bit resolution, which is due to reduction of the DC values and low frequency spectrum.

Perfusion culture system: Synovial fibroblasts modulate articular chondrocyte matrix synthesis in vitro

Objective To investigate the interactions of chondrocyte metabolism by synovial cells and synovial supernatants in a new perfusion co-culture system. Methods Chondrocytes and synovial fibroblasts were obtained from knee joints of slaughtered adult cattle. For experimental studies chondrocytes and synovial fibroblasts were placed together into a perfusion chamber (co-culture) or were placed into two different perfusion culture containers, which were connected by a silicone tube (culturing of chondrocytes with synovial supernatants). A control setup was used without synovial cells. Chondrocyte proliferation was shown by measurement of DNA content. The proteoglycan synthesis was quantified using 35SO 4 2−-labelling and the dimethylmethylene blue assay. 3H-proline incorporation was used to estimate the protein biosynthesis. Type II collagen synthesis was measured by ELISA, furthermore extracellular matrix deposition was monitored immunohistochemically (collagen types I/II). Regarding to the role of reactive oxygen species LDH release before and after stimulation with hydrogen peroxide was measured. Results The proliferation of chondrocytes shows an increase in monoculture as well as in co-culture or in culture with synovial supernatants more than fivefold within 12 days. 3H-proline incorporation as a marker for chondrocytes biosynthetic activity decreases in co-culture system and in culture with synovial supernatants. A similar effect is seen measuring total proteoglycan content as well as the 35SO 4 2− incorporation in chondrocytes. Co-culturing and culturing with synovial supernatants lead to a significant decrease of proteoglycan release and content. Quantification of collagen type II by ELISA shows significant lower amounts of native collagen type II in the extracellular matrix of co-cultured chondrocytes as well as in culture with synovial supernatants. The membrane damage of chondrocytes by hydrogen peroxide is reduced when chondrocytes are co-cultured with synovial fibroblasts. Conclusion The co-culture perfusion system is a new tool to investigate interactions of different cell types with less artificial interferences. Our results suggest that synovial supernatants and synovial fibroblasts modulate the biosynthetic activity and the matrix deposition of chondrocytes as well as the susceptibility to radical attack of reactive oxygen species.

A new methodology for determining dispersion coefficient using ordinary and partial differential transport equations

The present study proposes a methodology for determining the effective dispersion coefficient based on the field measurements performed in Gwangju (GJ) Creek in South Korea which is environmentally degraded by the artificial interferences such as weirs and culverts. Many previous works determining the dispersion coefficient were limited in application due to the complexity and artificial interferences in natural stream. Therefore, the sequential combination of N-Tank-In-Series (NTIS) model and Advection-Dispersion-Reaction (ADR) model was proposed for evaluating dispersion process in complex stream channel in this study. The series of water quality data were intensively monitored in the field to determine the effective dispersion coefficient of E. coli in rainy day. As a result, the suggested methodology reasonably estimates the dispersion coefficient for GJ Creek with 1.25 m(2)/s. Also, the sequential combined method provided Number of tank-Velocity-Dispersion coefficient (NVD) curves for convenient evaluation of dispersion coefficient of other rivers or streams. Comparing the previous studies, the present methodology is quite general and simple for determining the effective dispersion coefficients which are applicable for other rivers and streams.

Subjective reactions to intervention with artificial interferences in subjects with and without a history of temporomandibular disorders

In a previous double-blind randomized controlled study, subjects with a history of temporomandibular disorder (TMD) reacted to artificial interference with more signs of TMD than did subjects with no TMD history. In the present study, we analysed the subjective reactions of these individuals on several symptom scales. Every day during the 2-week follow-up period, the subjects rated the intensity of their symptoms on 9 VAS scales (occlusal discomfort, chewing difficulties, tender teeth, fatigue in the jaws, headache, facial pain, opening difficulty, bruxism, ear symptoms). Subjects with a history of TMD and true interferences reported stronger symptoms than subjects with no TMD history and placebo interferences. The most prominent symptoms were occlusal discomfort and chewing difficulties. The difference in outcome between the groups with and without a TMD history suggests that there are individual differences in vulnerability to occlusal interferences. It is likely that the etiological role of occlusal interferences in TMD has not been correctly addressed in previous studies on artificial interferences.

Environmental factors affecting establishment and expansion of the invasive alien species of tree of heaven (Ailanthus altissima) in Seoripool Park, Seoul

Abstract Tree of heaven (Ailanthus altissima Swingle) as an invasive alien plant, appeared usually in the disturbed locations such as road‐side, incised slope, and trampling path‐side. They appeared abundantly in the trampling path‐side but they did not appear or were rare in the interior of forest. Density and importance value of tree of heaven were proportionate to the relative light intensity measured according to distance from the trampling path toward forest interior and closely related to the breadth of trampling path as well. They were associated with annual, other exotic species or ruderal plants well. Distributional pattern of mature trees of them in the study area and its surrounding environments implied that they were introduced intentionally. Size class distribution of them showed that they are in expansion and artificial interferences such as, installing physical training space and developing hiking course functioned as trigger factors in their invasion and expansion. The results support the ...

Psychological factors and responses to artificial interferences in subjects with and without a history of temporomandibular disorders

Objective. It has often been suggested that psychological factors play a role in temporomandibular disorders (TMD). However, reports on psychological factors in TMD patients and controls have been equivocal. In a previous double-blind randomized controlled study, subjects with a TMD history showed more clinical signs and subjective symptoms and adapted less well to the artificial interferences than subjects without an earlier TMD history. In the present study, we analyzed the associations of psychological factors with symptom responses and adaptation to interferences. Material and Methods. Before the intervention, the subjects filled in questionnaires dealing with personality traits, level of psychological and somatic stress symptoms, coping strategies, and health beliefs. Every day during the 2-week follow-up period, the subjects rated the intensity of their symptoms on 9 modified visual analog scales (VAS). Results. Health hardiness, positive socialization history and inhibition of aggression were associated with weaker symptom responses and better adaptation to true artificial interferences. Some personality characteristics in subjects with an earlier TMD history tended to associate with higher symptom reporting despite the type of intervention. Conclusions. Psychological factors appeared significant for the symptom responses to artificial interferences, and they seem to play a different role in responses in subjects with an earlier TMD history compared to those without.

Distribution pattern of white snakeroot as an invasive alien plant and restoration strategy to inhibit its expansion in Seoripool park, Seoul

White snakeroot (Ageratina altissima (L.) R. King & H. Robinson) as an invasive alien plant appeared more abundantly at lower elevations where frequent artificial interferences prevailed than at hi...

Psychological factors and adaptation to artificial interferences in healthy subjects with and without TMD history

It has often been suggested that psychological factors play a role in temporomandibular disorders (TMD). However, reports on psychopathology and personality characteristics in TMD patients and controls have been equivocal. We have reported in a double‐blind RCT (LeBell et al., 2000) that subjects with a previous TMD history react differently in terms of TMD signs and symptoms to artificial interferences than subjects with no earlier TMD history. In the present study, we compared the psychological characteristics of these subjects and analysed the role of psychological factors in the adaptation process.The study sample of 47 women consisted of two groups: 26 women (mean age 24) without and 21 women (mean age 31) with TMD history. The subjects with TMD history had been treated earlier and they felt healthy when the intervention started. The groups were divided into true interference and placebo interference subgroups. Before the intervention, the subjects were interviewed. They also filled in questionnaires dealing with psychological and somatic symptoms, daily stress, coping strategies, personality characteristics, health hardiness and illness beliefs. During the 2‐week follow‐up period, the subjects rated the intensity of 10 symptoms on the visual analogue scale (VAS) scale and their impact on vocational and leisure time functioning. In addition, daily stress, life changes, somatic and psychological symptoms and coping with pain were explored. In general, the groups were similar in their psychological characteristics. There were, however, some differences in coping strategies. At the end of the intervention, the subjects with TMD history and exposed to true interferences reported more frequently than the other subjects muscle tension and neurological symptoms, thus indicating greater sensitivity to artificial interferences. This difference cannot be attributed to the observed base‐line personality characteristics as the groups did not differ in them. However, differences in coping strategies may play a role in the impaired adaptation.The financial support of Finska Läkaresäliskapet is gratefully acknowledged.

Effect of artificial occlusal interferences depends on previous experience of temporomandibular disorders

Studies on artificial interferences in subjects with no temporomandibular (TMD) history have shown adaptation to the interference within a fairly short period of time. The role of occlusal factors in the etiology of TMD has therefore been questioned. The results might have been different, however, if subjects with a prior TMD history had been included in the study groups. To test this assumption in a randomized double-blind clinical set-up, we included healthy women without (n = 26) as well as with (n = 21) an earlier TMD history. Both groups were randomly divided into true and placebo interference groups. Artificial interferences were introduced in the true interference groups and simulated in the placebo groups. The subjects were followed for 2 weeks, after which the interferences were removed. The subjects without a TMD history showed fairly good adaptation to the interferences, but the subjects with a TMD history and true interferences showed a significant increase in clinical signs compared to the other groups. We suggest that the etiological role of occlusal interferences in TMD may not have been correctly addressed in previous studies with artificial interferences and allow no conclusions as regards TMD etiology.

Targeted expression of major histocompatibility complex (MHC) class II molecules demonstrates that dendritic cells can induce negative but not positive selection of thymocytes in vivo.

It is well established that lymphoid dendritic cells (DC) play an important role in the immune system. Beside their role as potent inducers of primary T cell responses, DC seem to play a crucial part as major histocompatibility complex (MHC) class II+ "interdigitating cells" in the thymus during thymocyte development. Thymic DC have been implicated in tolerance induction and also by some authors in inducing major histocompatibility complex restriction of thymocytes. Most of our knowledge about thymic DC was obtained using highly invasive and manipulatory experimental protocols such as thymus reaggregation cultures, suspension cultures, thymus grafting, and bone marrow reconstitution experiments. The DC used in those studies had to go through extensive isolation procedures or were cultured with recombinant growth factors. Since the functions of DC after these in vitro manipulations have been reported to be not identical to those of DC in vivo, we intended to establish a system that would allow us to investigate DC function avoiding artificial interferences due to handling. Here we present a transgenic mouse model in which we targeted gene expression specifically to DC. Using the CD 11c promoter we expressed MHC class II I-E molecules specifically on DC of all tissues, but not on other cell types. We report that I-E expression on thymic DC is sufficient to negatively select I-E reactive CD4+ T cells, and to a less complete extent, CD8+ T cells. In contrast, it only DC expressed I-E in a class II-deficient background, positive selection of CD4+ T cells could not be observed. Thus negative, but not positive, selection events can be induced by DC in vivo.

Driving gene expression specifically in dendritic cells.

Lymphoid dendritic cells (DC) play an important role in the immune system. They are potent inducers of primary T cell responses and play a crucial part as MHC class II+ “interdigitating cells” in the thymus during thymocyte development. Most of our knowledge about DC was obtained using highly invasive and manipulatory experimental protocols. Since the functions of DC after these in vitro manipulations have been reported not to be identical to those of DC in vivo (1), we intended to establish a system that would allow us to investigate DC-function avoiding artificial interferences due to handling. Here we present a transgenic mouse system in which we targeted gene expression specifically to DC. Using the mouse CD11c promoter we expressed MHC class II I-E molecules specifically on DC of all tissues, but not on other cell types.