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Invasive Wasserpflanzen im Aquarium
No full textMit Aquarien lassen sich zu Hause faszinierende Unterwasserwelten herstellen. Daher sind im Handel viele verschiedene Pflanzenarten zur Bereicherung von Aquarien erhältlich. Einige wenige dieser Arten können jedoch problematisch werden, wenn sie in Gewässer der freien Natur gelangen und dort ein invasives Verhalten zeigen. Sie sind in der Lage, die Vielfalt heimischer, wildlebender Arten zu verdrängen und zu gefährden. In diesem Faltblatt werden beliebte Arten vorgestellt und Hinweise zum Umgang mit diesen gegeben.
Redaktionsschluss: 01.12.202
A sleep-active neuron can promote survival while sleep behavior is disturbed
No full textSleep is controlled by neurons that induce behavioral quiescence and physiological restoration. It is not known, however, how sleep neurons link sleep behavior and survival. In Caenorhabditis elegans, the sleep-active RIS neuron induces sleep behavior and is required for survival of starvation and wounding. Sleep-active neurons such as RIS might hypothetically promote survival primarily by causing sleep behavior and associated conservation of energy. Alternatively, RIS might provide a survival benefit that does not depend on behavioral sleep. To probe these hypotheses, we tested how activity of the sleep-active RIS neuron in Caenorhabditis elegans controls sleep behavior and survival during larval starvation. To manipulate the activity of RIS, we expressed constitutively active potassium channel (twk-18gf and egl-23gf) or sodium channel (unc-58gf) mutant alleles in this neuron. Low levels of unc-58gf expression in RIS increased RIS calcium transients and sleep. High levels of unc-58gf expression in RIS elevated baseline calcium activity and inhibited calcium activation transients, thus locking RIS activity at a high but constant level. This manipulation caused a nearly complete loss of sleep behavior but increased survival. Long-term optogenetic activation also caused constantly elevated RIS activity and a small trend towards increased survival. Disturbing sleep by lethal blue-light stimulation also overactivated RIS, which again increased survival. FLP-11 neuropeptides were important for both, induction of sleep behavior and starvation survival, suggesting that FLP-11 might have divergent roles downstream of RIS. These results indicate that promotion of sleep behavior and survival are separable functions of RIS. These two functions may normally be coupled but can be uncoupled during conditions of strong RIS activation or when sleep behavior is impaired. Through this uncoupling, RIS can provide survival benefits under conditions when behavioral sleep is disturbed. Promoting survival in the face of impaired sleep might be a general function of sleep neurons
Schriftenreihe des Nationalparks Sächsische Schweiz
No full textFachbeiträge der Nationalparkverwaltung Sächsische Schweiz, herausgegeben als Schrifteneihe
An embedding observer for nonlinear dynamical systems with global convergence
No full textState observers for nonlinear systems are often designed for a canonical form of this system. However, this form may possess singular points, where the vector field is not defined or a Lipschitz condition is not fulfilled. This unpleasant behavior can possibly be avoided using an embedding into a higher dimensional space. A construction of such an embedding and the corresponding inverse map is discussed for polynomial systems using methods from algebraic geometry
Crack monitoring on concrete structures: Comparison of various distributed fiber optic sensors with digital image correlation method
No full textThe quality of strain measurements using distributed fiber optic sensors (DFOS) depends largely on the bond between the host material and the optical fiber. Experimental investigations were carried out to test the suitability of five different DFOS types for crack monitoring. The DFOS were subsequently bonded to two 4 m long reinforced concrete (RC) beams, so that the influence of the application technique could be evaluated. DFOS measurements were verified by digital image correlation (DIC) and electrical strain gauges (SGs). For the different DFOS types, clear differences in the measured strain curves and determined crack widths were observed. The focus was on two robust DFOS, which can be deployed on construction sites. Compared to the layered sensing cable, a monolithic DFOS showed a clear strain distribution with pronounced strain peaks even for closely spaced cracks. The crack widths obtained by integrating the strain curves showed high agreement with DIC measurements
Immediate diagnosis of cutaneous metastases with optical coherence tomography, line-field confocal optical coherence tomography and dermoscopy: A case series
No full textBackground
Cutaneous metastases (CM) are a frequent finding in the follow-up of malignant tumours.
Objectives
CM were examined with dermoscopy, optical coherence tomography (OCT), dynamic OCT and line-field confocal OCT (LC-OCT) to describe common findings.
Methods
In the University Hospital Carl Gustav Carus Dresden, Germany, 18 patients with 61 CM were examined with dermoscopy. CM (n = 43, 31 melanoma metastases, two metastases of renal carcinoma, five metastases of cutaneous squamous cell carcinoma and five metastases of pleomorphic dermal sarcoma) were examined with OCT (VivoSight® Michelson Diagnostics). Additional 18 melanoma metastases were examined with LC-OCT (deepLive™; Damae Medical).
Results
CM were localized on the head, trunk, neck and limbs. Dermoscopy patterns were angioma-like, nevus-like nonglobular, nevus-like globular, blue nevus-like and unspecific. CM showed an ulceration, hyperkeratosis with increased entrance signal and disturbed architecture of the epidermis in OCT. In deeper metastases, the dermoepidermal junction (DEJ) was normal; in most cases it was disturbed. CM were visible as subepidermal hyporeflective roundish area, with septae, with either clear margin and shadowing or blurred margin. DOCT showed dot, coiled, serpiginous and branched vessels; there was a disarray in size and distribution and vessels were converging on the centre of the metastasis. In LC-OCT, CM showed enhanced entrance signal and disturbed architecture of a thinned epidermis, ulceration, atypical honeycomb or cobblestone pattern as well as a broken DEJ. In the dermis, a hyporeflective roundish area with clusters of hyporeflective cells with septae, clear margin and clefting or blurred margin was visible; the hyporeflective area was surrounded by bundles of connective tissue. Subepidermal vessels differentiated in size and distribution. Inflammatory, dendritic and pagetoid cells were visible.
Conclusions
OCT and LC-OCT may be useful tools for immediate diagnosis, localization of CM and monitoring under treatment in addition to conventional methods like ultrasound and histopathology
A study on the material properties of novel PEGDA/gelatin hybrid hydrogels polymerized by electron beam irradiation
No full textGelatin-based hydrogels are highly desirable biomaterials for use in wound dressing, drug delivery, and extracellular matrix components due to their biocompatibility and biodegradability. However, insufficient and uncontrollable mechanical properties and degradation are the major obstacles to their application in medical materials. Herein, we present a simple but efficient strategy for a novel hydrogel by incorporating the synthetic hydrogel monomer polyethylene glycol diacrylate (PEGDA, offering high mechanical stability) into a biological hydrogel compound (gelatin) to provide stable mechanical properties and biocompatibility at the resulting hybrid hydrogel. In the present work, PEGDA/gelatin hybrid hydrogels were prepared by electron irradiation as a reagent-free crosslinking technology and without using chemical crosslinkers, which carry the risk of releasing toxic byproducts into the material. The viscoelasticity, swelling behavior, thermal stability, and molecular structure of synthesized hybrid hydrogels of different compound ratios and irradiation doses were investigated. Compared with the pure gelatin hydrogel, 21/9 wt./wt. % PEGDA/gelatin hydrogels at 6 kGy exhibited approximately up to 1078% higher storage modulus than a pure gelatin hydrogel, and furthermore, it turned out that the mechanical stability increased with increasing irradiation dose. The chemical structure of the hybrid hydrogels was analyzed by Fourier-transform infrared (FTIR) spectroscopy, and it was confirmed that both compounds, PEGDA and gelatin, were equally present. Scanning electron microscopy images of the samples showed fracture patterns that confirmed the findings of viscoelasticity increasing with gelatin concentration. Infrared microspectroscopy images showed that gelatin and PEGDA polymer fractions were homogeneously mixed and a uniform hybrid material was obtained after electron beam synthesis. In short, this study demonstrates that both the presence of PEGDA improved the material properties of PEGDA/gelatin hybrid hydrogels and the resulting properties are fine-tuned by varying the irradiation dose and PEGDA/gelatin concentration
A comparative study of fully implicit staggered and monolithic solution methods.: Part II: Coupled excitation–contraction equations of cardiac electromechanics
No full textA comparative study of fully implicit staggered and monolithic solution algorithms for the coupled bidomain equations of cardiac electrophysiology was discussed in Part I (JCAM 407:114021, 2022). In this follow-up study, we further employ the similar approach and present an extensive comparative analysis between the staggered and monolithic solution techniques for the coupled partial differential equations (PDEs) of cardiac electromechanics both in the monodomain and bidomain setting. For the monolithic solution technique, we adopt the work of Göktepe et al. (CM 45: 227-243, 2010) and Dal et al. (CMAME 253: 353-336, 2013), where the governing PDEs of the excitation–contraction problem are solved simultaneously and all rate equations are treated with an implicit time integration scheme. For the staggered scheme, however, we simply suggest a decoupled solution of the governing PDEs while keeping other aspects of the monolithic algorithm the same, such as utilization of the implicit time integration scheme and coupling of ordinary differential equations, which describe the state variables of cardiac electrophysiology, to the parabolic PDE of the electrophysiology. Both solution algorithms are applied to several problems, where we simulate regular planar wave propagations and scroll waves for different spatial and temporal resolution and material parameters. The comparison between the solution schemes is performed in terms of accuracy, efficiency and stability. We reveal that for regular wave propagation the results of different solution algorithms are identical. The only deviation is observed during scroll wave propagation, if the parameters controlling the mutual interaction between the mechanical and electrical field are relatively large and at the same time if the time increment is big, e.g., = 2.0 ms. Nevertheless, the suggested staggered solution scheme yields almost identical results even for high coupling if smaller time increments are used. Besides, the staggered scheme provides an enormous gain in computational efficiency, particularly, as the number of degrees of freedom is increased and we do not encounter any stability issue arising specifically from the decoupled solution of the governing PDEs. Similar to the conclusion that was made for cardiac electrophysiology in Part I, we report that the suggested fully implicit staggered solution algorithm has a tremendous application potential for computer simulations of excitation–contraction coupling of the heart both in the monodomain and bidomain setting
Exposure traced in daily life: improvements in ecologically assessed social and physical activity following exposure-based psychotherapy for anxiety disorders
No full textBackground: Although exposure-based cognitive-behavioral therapy for anxiety disorders has frequently been proven effective, only few studies examined whether it improves everyday behavioral outcomes such as social and physical activity.
Methods: 126 participants (85 patients with panic disorder, agoraphobia, social anxiety disorder, or specific phobias, and 41 controls without mental disorders) completed smartphone-based ambulatory ratings (activities, social interactions, mood, physical symptoms) and motion sensor-based indices of physical activity (steps, time spent moving, metabolic activity) at baseline, during, and after exposure-based treatment.
Results: Prior to treatment, patients showed reduced mood and physical activity relative to healthy controls. Over the course of therapy, mood ratings, interactions with strangers and indices of physical activity improved, while reported physical symptoms decreased. Overall results did not differ between patients with primary panic disorder/agoraphobia and social anxiety disorder. Higher depression scores at baseline were associated with larger changes in reported symptoms and mood ratings, but smaller changes in physical activity
Conclusions: Exposure-based treatment initiates increased physical activity, more frequent interaction with strangers, and improvements in everyday mood. The current approach provides objective and fine-graded pro cess and outcome measures that may help to further improve treatments and possibly reduce relapse
Modellierung des elastischen Verhaltens von Umformmaschinen als Beitrag zur Verbesserung des digitalen Werkzeugentstehungsprozesses
No full textIn der Produktionstechnik verstärken sich parallel zum Trend der Individualisierung von Produkten seit Längerem die Bedürfnisse nach der Sicherstellung einer gleichbleibenden Produktqualität, von schnelleren Produktanläufen und einer Kostenreduktion im globalen Wettbewerb. Bezogen auf die Umformtechnik als Verfahren der (Groß-)Serienfertigung beeinflussen das Umformwerkzeug sowie dessen Entstehungsprozess maßgeblich diese Herausforderungen. Besonders im Bereich der Blechumformung kommt dem weitgehend erfahrungsbasierten und manuellen Tryout-Prozess von Umformwerkzeugen eine hohe Relevanz aufgrund seines Einflusses auf das Produkt sowie als Faktor bezüglich des monetären und zeitlichen Aufwandes zu. Einer der dominierenden Einflussfaktoren hierbei ist das Verhalten der beteiligten Umformmaschine, wodurch sich erhebliche Einsparpotentiale durch dessen Kenntnis sowie die Einbeziehung in den dem Tryout vorgelagerten Konstruktionsprozess des Umformwerkzeuges ergeben.
Für die Modellierung von Umformmaschinen existieren zum derzeitigen Zeitpunkt verschiedene Ansätze, die in Formulierung, Umfang und Zielsetzung individuell auf den jeweiligen Einsatzfall hin zugeschnitten sind. Ein breiter Einsatz ist dabei bisher nicht möglich. Die vorliegende Abhandlung stellt deshalb die Erstellung weitgehend allgemein einsetzbarer Modelle des mechanischen Verhaltens von Umformmaschinen in den Vordergrund. Diese ermöglichen eine Verkürzung des Werkzeugentstehungsprozesses insbesondere durch eine frühzeitige Digitalisierung. Wünschenswerter Nebeneffekt ist ist die Qualifizierung der realen Umformmaschine durch einen digitalen Zwilling hin zu einem cyber-physischen Produktionssystem. Der Fokus liegt hierbei auf der Abbildung des elastischen Deformationsverhaltens der Umformmaschine, welches maßgeblich durch die Komponenten Pressenstößel und Pressentisch im Bereich der Spannflächen hin zum Umformwerkzeug bestimmt wird. Hierfür werden Ansätze für die Bildung von Modellen entwickelt, welche sowohl in Finite-Elemente-Simulationen als auch unabhängig von FE-Umgebungen verwendet werden können. Die Modelle basieren auf dem im Vorfeld zu vermessenden elastischen Verhalten der Spannflächen, für das Belastungsfälle definiert und Krafteinleitung sowie die messtechnische Erfassung der Verlagerungen umzusetzen sind. Anspruch der Modelle ist die korrekte Wiedergabe des Deformationsverhalten für beliebige aus dem jeweiligen Umformwerkzeug resultierende Belastungsverteilungen. Weiterhin gilt es zu ermitteln, welche Möglichkeiten durch die Kenntnis des elastischen Verhaltens und dessen Zugänglichkeit in FE-Simulationen entstehen. Hierfür wurde eine Validierung auf Basis eines Demonstratorwerkzeuges durchgeführt