Schülervorstellungen zum Thema Schall

Die Erforschung von Schülervorstellungen nimmt in der Physikdidaktik eine zentrale Rolle ein, denn Schülerinnen und Schüler kommen nicht als unbeschriebene Blätter in den Unterricht, sondern bringen ein Set von vorunterrichtlichen Vorstellungen mit. Im Rahmen dieser Arbeit wurden Schülervorstellungen zum Thema Schall erforscht. Zunächst wurden sie mit einer qualitativen Vorstudie aufgespürt und in einer zweiten Phase dann quantitativ validiert. Der Fokus lag dabei lehrplanbedingt auf der Sekundarstufe I der allgemeinbildenden höheren Schule und so konnten sowohl einige Vorstellungsschwierigkeiten als auch einige vorunterrichtliche Präkonzepte eruiert werden, die Schülerinnen und Schüler in den Physikunterricht mitbringen. So weisen Schülerinnen und Schüler beispielsweise Radiowellen dem Gebiet des Schalls zu, glauben, dass sich Schall nicht durch Festkörper ausbreitet und eine Schallquelle nichts Bewegliches sein muss. Dass höhere Töne lauter und lautere Töne schneller sind, sind zwei andere Schülervorstellungen. Auch die Schallgeschwindigkeit ist für sie schwer zu fassen und somit für viele Kinder auch von einem schnellen Flugzeug nicht zu erreichen.The research of pupils' misconceptions plays an important role in physics didactics, because pupils do not enter the classroom as a tabula rasa, but bring along a set of pre-lesson ideas. In the course of this thesis the pupils' misconceptions were researched on the subject of sound. First of all, they were tracked with a qualitative pre-study and then quantitatively validated in a second phase. Due to the curriculum, the research was realized in the secondary academic school (lower level). Thus some difficulties of conception as well as some pre-lesson preconceptions, which students bring in the physics lessons, could be found. For example, pupils link radio waves with sound, think that sound doesn’t propagate through solids, and that a sound source does not have to be movably. Two other misconceptions are: Higher tones are louder and louder tones are faster. The speed of sound is also a difficult issue for them and therefore another misconception is, that it cannot be reached by a fast plane

Left ventricular mass and systolic function in children with chronic kidney disease-comparing echocardiography with cardiac magnetic resonance imaging.

BACKGROUND Increased left ventricular mass (LVM) is an important risk marker of uremic cardiovascular disease. Calculation of LVM by echocardiography (Echo) relies on geometric assumptions and in adults on hemodialysis overestimates LVM compared to cardiac magnetic resonance (CMR). We compare both techniques in children with chronic kidney disease (CKD). METHODS Concurrent Echo and CMR was performed in 25 children with CKD (14 after kidney transplantation) aged 8-17 years. RESULTS Compared to normal children, CMR-LVM was increased (standard deviation score (SDS) 0.39 ± 0.8 (p = 0.03)), stroke volume and cardiac output decreased (SDS -1.76 ± 1.1, p = 0.002 and -1.11 ± 2.0, p = 0.001). CMR-LVM index but not Echo-LVMI correlated to future glomerular filtration rate (GFR) decline (r = -0.52, p = 0.01). Mean Echo-LVM was higher than CMR-LVM (117 ± 40 vs. 89 ± 29 g, p < 0.0001), with wide limits of agreement (-6.2 to 62.8 g). The Echo-CMR LVM difference increased with higher Echo-LVMI (r = 0.77, p < 0.0001). Agreement of classifying left ventricular hypertrophy was poor with Cohen's kappa of 0.08. Mean Echo and CMR-ejection fraction differed by 1.42% with wide limits of agreement (-12.6 to 15.4%). CONCLUSIONS Echo overestimates LVM compared to CMR, especially at higher LVM. Despite this, CMR confirms increased LVM in children with CKD. Only CMR-LVMI but not Echo-LVMI correlated to future GFR decline

Haptoglobin Attenuates Cerebrospinal Fluid Hemoglobin-Induced Neurological Deterioration in Sheep

Secondary brain injury (SBI) occurs with a lag of several days post-bleeding in patients with aneurysmal subarachnoid hemorrhage (aSAH) and is a strong contributor to mortality and long-term morbidity. aSAH-SBI coincides with cell-free hemoglobin (Hb) release into the cerebrospinal fluid. This temporal association and convincing pathophysiological concepts suggest that CSF-Hb could be a targetable trigger of SBI. However, sparse experimental evidence for Hb’s neurotoxicity in vivo defines a significant research gap for clinical translation. We modeled the CSF-Hb exposure observed in aSAH patients in conscious sheep, which allowed us to assess neurological functions in a gyrencephalic species. Twelve animals were randomly assigned for 3-day bi-daily intracerebroventricular (ICV) injections of either Hb or Hb combined with the high-affinity Hb scavenger protein haptoglobin (Hb-Hp, CSL888). Repeated CSF sampling confirmed clinically relevant CSF-Hb concentrations. This prolonged CSF-Hb exposure over 3 days resulted in disturbed movement activity, reduced food intake, and impaired observational neuroscores. The Hb-induced neurotoxic effects were significantly attenuated when Hb was administered with equimolar haptoglobin. Preterminal magnetic resonance imaging (MRI) showed no CSF-Hb-specific structural brain alterations. In both groups, histology demonstrated an inflammatory response and revealed enhanced perivascular histiocytic infiltrates in the Hb-Hp group, indicative of adaptive mechanisms. Heme exposure in CSF and iron deposition in the brain were comparable, suggesting comparable clearance efficiency of Hb and Hb-haptoglobin complexes from the intracranial compartment. We identified a neurological phenotype of CSF-Hb toxicity in conscious sheep, which is rather due to neurovascular dysfunction than structural brain injury. Haptoglobin was effective at attenuating CSF-Hb-induced neurological deterioration, supporting its therapeutic potential

Magnetic resonance tissue phase mapping demonstrates altered left ventricular diastolic function in children with chronic kidney disease

BACKGROUND: Echocardiographic examinations have revealed functional cardiac abnormalities in children with chronic kidney disease. OBJECTIVE: To assess the feasibility of MRI tissue phase mapping in children and to assess regional left ventricular wall movements in children with chronic kidney disease. MATERIALS AND METHODS: Twenty pediatric patients with chronic kidney disease (before or after renal transplantation) and 12 healthy controls underwent tissue phase mapping (TPM) to quantify regional left ventricular function through myocardial long (Vz) and short-axis (Vr) velocities at all 3 levels of the left ventricle. RESULTS: Patients and controls (age: 8 years-20 years) were matched for age, height, weight, gender and heart rate. Patients had higher systolic blood pressure. No patient had left ventricular hypertrophy on MRI or diastolic dysfunction on echocardiography. Fifteen patients underwent tissue Doppler echocardiography, with normal z-scores for mitral early diastolic (VE), late diastolic (VA) and peak systolic (VS) velocities. Throughout all left ventricular levels, peak diastolic Vz and Vr (cm/s) were reduced in patients: Vzbase -10.6 ± 1.9 vs. -13.4 ± 2.0 (P < 0.0003), Vzmid -7.8 ± 1.6 vs. -11 ± 1.5 (P < 0.0001), Vzapex -3.8 ± 1.6 vs. -5.3 ± 1.6 (P = 0.01), Vrbase -4.2 ± 0.8 vs. -4.9 ± 0.7 (P = 0.01), Vrmid -4.7 ± 0.7 vs. -5.4 ± 0.7 (P = 0.01), Vrapex -4.7 ± 1.4 vs. -5.6 ± 1.1 (P = 0.05). CONCLUSION: Tissue phase mapping is feasible in children and adolescents. Children with chronic kidney disease show significantly reduced peak diastolic long- and short-axis left ventricular wall velocities, reflecting impaired early diastolic filling. Thus, tissue phase mapping detects chronic kidney disease-related functional myocardial changes before overt left ventricular hypertrophy or echocardiographic diastolic dysfunction occurs

MVA vectors expressing conserved influenza proteins protect mice against lethal challenge with H5N1, H9N2 and H7N1 viruses.

BACKGROUND: The availability of a universal influenza vaccine able to induce broad cross-reactive immune responses against diverse influenza viruses would provide an alternative to currently available strain-specific vaccines. We evaluated the ability of vectors based on modified vaccinia virus Ankara (MVA) expressing conserved influenza proteins to protect mice against lethal challenge with multiple influenza subtypes. METHODS: Mice were immunized with MVA vectors expressing H5N1-derived nucleoprotein (NP), the stem region of hemagglutinin (HA), matrix proteins 1 and 2 (M1 and M2), the viral polymerase basic protein 1 (PB1), or the HA stem fused to a quadrivalent matrix protein 2 extracellular domain (M2e). Immunized mice were challenged with lethal doses of H5N1, H7N1 or H9N2 virus and monitored for disease symptoms and weight loss. To investigate the influence of previous exposure to influenza virus on protective immune responses induced by conserved influenza proteins, mice were infected with pandemic H1N1 virus (H1N1pdm09) prior to immunization and subsequently challenged with H5N1 virus. Antibody and T cell responses were assessed by ELISA and flow cytometry, respectively. RESULTS: MVA vectors expressing NP alone, or co-expressed with other conserved influenza proteins, protected mice against lethal challenge with H5N1, H7N1 or H9N2 virus. Pre-exposure to H1N1pdm09 increased protective efficacy against lethal H5N1 challenge. None of the other conserved influenza proteins provided significant levels of protection against lethal challenge. NP-expressing vectors induced high numbers of influenza-specific CD4(+) and CD8(+) T cells and high titer influenza-specific antibody responses. Higher influenza-specific CD4(+) T cell responses and NP-specific CD8(+) T cell responses were associated with increased protective efficacy. CONCLUSIONS: MVA vectors expressing influenza NP protect mice against lethal challenge with H5N1, H7N1 and H9N2 viruses by a mechanism involving influenza-specific CD4(+) and CD8(+) T cell responses

Immunogenicity and protective efficacy of a Vero cell culture-derived whole-virus H7N9 vaccine in mice and guinea pigs.

A novel avian H7N9 virus with a high case fatality rate in humans emerged in China in 2013. We evaluated the immunogenicity and protective efficacy of a candidate Vero cell culture-derived whole-virus H7N9 vaccine in small animal models.Antibody responses induced in immunized DBA/2J mice and guinea pigs were evaluated by hemagglutination inhibition (HI), microneutralization (MN), and neuraminidase inhibition (NAi) assays. T-helper cell responses and IgG subclass responses in mice were analyzed by ELISPOT and ELISA, respectively. Vaccine efficacy against lethal challenge with wild-type H7N9 virus was evaluated in immunized mice. H7N9-specific antibody responses induced in mice and guinea pigs were compared to those induced by a licensed whole-virus pandemic H1N1 (H1N1pdm09) vaccine.The whole-virus H7N9 vaccine induced dose-dependent H7N9-specific HI, MN and NAi antibodies in mice and guinea pigs. Evaluation of T-helper cell responses and IgG subclasses indicated the induction of a balanced Th1/Th2 response. Immunized mice were protected against lethal H7N9 challenge in a dose-dependent manner. H7N9 and H1N1pdm09 vaccines were similarly immunogenic.The induction of H7N9-specific antibody and T cell responses and protection against lethal challenge suggest that the Vero cell culture-derived whole-virus vaccine would provide an effective intervention against the H7N9 virus

Correlation of immunological assays with rOspA-1/2 vaccine-induced protective efficacy.

<p>Serum antibody titers quantified by ELISA, CI-ELISA, SB assay and killing assay are shown for OspA-1/2-immunized mice which were either protected from or infected by (<b>A</b>) needle challenge with <i>B. burgdorferi s.s.</i> strain ZS7 or (<b>B</b>) tick challenge with <i>B. afzelii</i>. Shown are the geometric mean titers of each group as well as individual serum titers. P values represent the strength of the correlation of assay titers with protective efficacy as calculated by the Mann-Whitney U test. Two serum samples were unavailable for evaluation in the <i>B. burgdorferi</i> s.s CI and killing assays; one serum sample was unavailable for evaluation in the <i>B. afzelii</i> CI assay.</p

GMT antibody titers and protection of vaccinated mice against challenge with <i>B. burgdorferi</i> s.s. and <i>B. afzelii</i>.

<p>GMT antibody titers and protection of vaccinated mice against challenge with <i>B. burgdorferi</i> s.s. and <i>B. afzelii</i>.</p