An understanding of falling bodies across schooling and experience based on the conceptual prevalence framework

In this article, we describe a study conducted online with 953 participants of varying levels of education and, when applicable, science/physics teaching experience. These participants were asked to solve a cognitive task in which many different pairs of objects were presented and to identify which, if any, would touch the ground first when dropped (in atmospheric or non-atmospheric environments). Recorded accuracies and response times allowed us to conduct an analysis based on the conceptual prevalence framework, which posits that the coexistence of conceptual and/or misconceptual resources can produce interference in response production. The results show that the influence of some of them decreases or, more surprisingly, increases with training. In fact, secondary and college physics teachers seem to cultivate some of them, and most likely have contributed to their spread. The implications for teaching and research are discussed.

Effects of reading contextualized physics problems among men and women: A psychophysiological approach

To counteract declining interest in science, contextualizing course material has been suggested, despite little evidence supporting this strategy. We assessed how reading physics problems in different contexts-none, technical, or humanistic-impacted performance and implicit cognitive and affective situational interest (SI) among undergraduate men and women (n = 60). We hypothesized that contextualized problems would increase cognitive SI, boosting performance. We also investigated existing hypotheses that this influence would be stronger when contexts matched stereotypical gender interests. Pupillometric and electroencephalographic data served to indicate cognitive SI, while electrodermal activity (EDA) and valence were measures of affective SI. Significantly higher valence was observed in decontextualized than humanistic problems (p = 0.003) specifically among men (p < 0.001). Greater EDA (p = 0.019) and decontextualized problems (p < 0.001) yielded greater performance than contextualized problems for all participants. Results emphasize the importance of affective SI and of avoiding gender biases in curricular development. This study encourages caution if implementing contextualization.

An fMRI study of scientists with a Ph.D. in physics confronted with naive ideas in science

A central challenge in developing conceptual understanding in science is overcoming naive ideas that contradict the content of science curricula. Neuroimaging studies reveal that high school and university students activate frontal brain areas associated with inhibitory control to overcome naive ideas in science, probably because they persist despite scientific training. However, no neuroimaging study has yet explored how persistent naive ideas in science are. Here, we report brain activations of 25 scientists with a Ph.D. in physics assessing the scientific value of naive ideas in science. Results show that scientists are slower and have lower accuracy when judging the scientific value of naive ideas compared to matched control ideas. fMRI data reveals that a network of frontal brain regions is more activated when judging naive ideas. Results suggest that naive ideas are likely to persist, even after completing a Ph.D. Advanced experts may still rely on high order executive functions like inhibitory control to overcome naive ideas when the context requires it.

Non-Graphical Solutions for Cattell’s Scree Test

Most of the strategies that have been proposed to determine the number of components that account for the most variation in a principal components analysis of a correlation matrix rely on the analysis of the eigenvalues and on numerical solutions. The Cattell’s scree test is a graphical strategy with a nonnumerical solution to determine the number of components to retain. Like Kaiser’s rule, this test is one of the most frequently used strategies for determining the number of components to retain. However, the graphical nature of the scree test does not definitively establish the number of components to retain. To circumvent this issue, some numerical solutions are proposed, one in the spirit of Cattell’s work and dealing with the scree part of the eigenvalues plot, and one focusing on the elbow part of this plot. A simulation study compares the efficiency of these solutions to those of other previously proposed methods. Extensions to factor analysis are possible and may be particularly useful with many low-dimensional components.

Critical role of c-Kit in beta cell function: increased insulin secretion and protection against diabetes in a mouse model

AIMS/HYPOTHESIS

The receptor tyrosine kinase, c-Kit, and its ligand, stem cell factor, control a variety of cellular processes, including pancreatic beta cell survival and differentiation as revealed in c-Kit ( Wv ) mice, which have a point mutation in the c-Kit allele leading to loss of kinase activity and develop diabetes. The present study further investigated the intrinsic role of c-Kit in beta cells, especially the underlying mechanisms that influence beta cell function.

METHODS

We generated a novel transgenic mouse model with c-KIT overexpression specifically in beta cells (c-KitβTg) to further examine the physiological and functional roles of c-Kit in beta cells. Isolated islets from these mice were used to investigate the underlying molecular pathway of c-Kit in beta cells. We also characterised the ability of c-Kit to protect animals from high-fat-diet-induced diabetes, as well as to rescue c-Kit ( Wv ) mice from early onset of diabetes.

RESULTS

c-KitβTg mice exhibited improved beta cell function, with significantly improved insulin secretion, and increased beta cell mass and proliferation in response to high-fat-diet-induced diabetes. c-KitβTg islets exhibited upregulation of: (1) insulin receptor and IRSs; (2) Akt and glycogen synthase kinase 3β phosphorylation; and (3) transcription factors important for islet function. c-KIT overexpression in beta cells also rescued diabetes observed in c-Kit ( Wv ) mice.

CONCLUSIONS/INTERPRETATION

These findings demonstrate that c-Kit plays a direct protective role in beta cells, by regulating glucose metabolism and beta cell function. c-Kit may therefore represent a novel target for treating diabetes.

Conditional β1-integrin-deficient mice display impaired pancreatic β cell function

β1-Integrin, a critical regulator of β cell survival and function, has been shown to protect against cell death and promote insulin expression and secretion in rat and human islet cells in vitro. The aim of the present study was to examine whether the knockout of β1-integrin in collagen I-producing cells would have physiological and functional implications in pancreatic endocrine cells in vivo. Using adult mice with a conditional knockout of β1-integrin in collagen I-producing cells, the effects of β1-integrin deficiency on glucose metabolism and pancreatic endocrine cells were examined. Male β1-integrin-deficient mice display impaired glucose tolerance, with a significant reduction in pancreatic insulin content (p < 0.01). Morphometric analysis revealed a significant reduction in β cell mass (p < 0.001) in β1-integrin-deficient mice, along with a significant decrease in β cell proliferation, Pdx-1 and Nkx6.1 expression when compared with controls. Interestingly, these physiological and morphometric alterations in female β1-integrin-deficient mice were less significant. Furthermore, β1-integrin-deficient mice displayed decreased FAK (p < 0.05) and ERK1/2 (p < 0.001) phosphorylation, reduced cyclin D1 levels (p < 0.001) and increased caspase 3 cleavage (p < 0.01), while no changes in Akt phosphorylation were observed, indicating that the β1-integrin signals through the FAK-MAPK-ERK pathway in vivo. Our results demonstrate that β1-integrin is involved in the regulation of glucose metabolism and contributes to the maintenance of β cell survival and function in vivo.

Hepatic metastases from leiomyosarcoma: MR features with histopathologic correlation

BACKGROUND

To determine the magnetic resonance (MR) imaging features of hepatic metastases from leiomyosarcoma and determine the pathologic basis for the MR appearance of these neoplasms.

METHODS

MR examinations of eight patients with a total of 16 hepatic metastases from leiomyosarcoma were retrospectively reviewed. Hepatic metastases originated from a primary gastrointestinal (n = 6), uterine (n = 1), or retroperitoneal (n = 1) leiomyosarcoma. Correlation between MR features and pathologic findings was performed in 11 metastases from which histologic material was obtained.

RESULTS

Among the 10 metastases seen on T1-weighted MR images, nine were homogeneous and one was heterogeneous. The latter contained areas of necrosis and hemorrhage on pathologic examination. Among the 16 metastases seen on T2-weighted MR images, 12 were well delineated and completely homogeneous, with a marked hyperintense signal ("hemangiomalike" pattern). These neoplasms were composed of smooth fibrous tissue without macroscopically visible areas of necrosis on pathologic examination. The remaining four metastases were heterogeneous and contained varying degrees of necrosis and hemorrhage or gelatinous tissue.

CONCLUSION

A hemangiomalike pattern is the most common feature on T2-weighted MR images. We found that homogeneous hyperintensity of hepatic metastases from leiomyosarcoma on T2-weighted MR image does not reflect cystic changes.

Hepatic leiomyosarcomas: CT features with pathologic correlation

The purpose of this study was to determine the computed tomographic (CT) features of hepatic leiomyosarcoma and to correlate them with pathologic findings. CT examinations of 15 patients with pathologically proven leiomyosarcoma of the liver were retrospectively reviewed. Three patients had primary leiomyosarcoma of the liver and 12 patients had 43 distinct hepatic metastases originating from a primary gastrointestinal (n = 8), uterine (n = 2) or retroperitoneal (n = 2) leiomyosarcoma. In the 11 patients who had partial hepatic resection or surgical biopsy of their tumors, a correlation was made between CT imaging and pathologic findings. Primary leiomyosarcomas showed heterogeneous enhancement; two displayed internal and peripheral enhancement, and one showed peripheral enhancement with a pseudocystic pattern (i.e. enhancing thick wall with internal nonenhancing low attenuation area). Leiomyosarcomas metastatic to the liver were homogeneous, showing no or moderate enhancement (10 of 43 metastases, 23%) or heterogeneous and predominantly peripheral enhancement (33 of 43 metastases, 77%). A pseudocystic pattern was seen in 13 of the 43 metastases (30%). Homogeneous tumors were made of smooth fibrous-like tissue without area of necrosis. Heterogeneous tumors contained varying degrees of necrosis and hemorrhage or gelatinous tissue. We found that primary and secondary hepatic leiomyosarcomas of the liver can exhibit different features. A pseudocystic pattern is uncommon. Furthermore, purely cystic tumors were not seen in our series.

MIC2 analysis in pediatric lymphomas and leukemias

Monoclonal antibodies to the glycoprotein product of the MIC2 gene strongly and reliably stain primitive neuroectodermal tumors and Ewing's sarcomas, and are negative in neuroblastomas and most rhabdomyosarcomas. Therefore, these antibodies are helpful in the diagnosis of small round cell tumors of childhood (SRCT). Lymphomas also are in the differential diagnosis of SRCT, but few have been studied with respect to MIC2 protein expression. In the present study we used the 12E7 antibody to assess MIC2 expression in 82 pediatric non-Hodgkin's lymphomas. Forty lymphoblastic, 22 small noncleaved, and 20 large cell lymphomas were studied. Strong immunoreactivity was found in 37 of the 40 (93%) lymphoblastic lymphomas, whereas only one of the 22 (5%) small noncleaved lymphomas was 12E7 positive. Four of the 20 (20%) large cell lymphomas also were immunoreactive. Three 12E7+ lymphoblastic lymphomas were primary in bone and were of B-progenitor lineage; Ewing's sarcoma was included in the initial differential diagnosis of these cases. Evaluation of 125 pediatric acute lymphocytic leukemia (ALL) cases for MIC2 expression showed similar results, with all 36 T-cell ALLs showing strong expression, one of eight B-cell (Burkitt-like) ALLs showing 12E7 expression, and 62 of 81 B-progenitor ALLs showing 12E7 positivity. We conclude that among the SRCTs, MIC2 expression is not limited to Ewing's sarcoma and primitive neuroectodermal tumors, but also shows strong and reliable expression in lymphoblastic lymphomas and related leukemias. MIC2 analysis continues to be helpful in the diagnosis of SRCT, provided that a panel of antibodies is used. In addition, the possibility that MIC2 analysis may aid in the distinction of lymphoblastic lymphomas from small noncleaved lymphomas needs to be further addressed.