Retrospective analysis of a STEM outreach event reveals positive influences on student attitudes toward STEM careers but not scientific methodology.

Substantial, involved, and expensive efforts to promote the dissemination of scientific knowledge and career interest in Science, Technology, Engineering, and Mathematics (STEM) are enthusiastically supported by many scientific, federal, and local organizations. The articulated underlying goals for these efforts include an enhanced public understanding of science and science-related policy, an increased diversity in STEM careers, and an increase in the future STEM workforce. This effort is primarily driven by an underperformance of the United States that includes poor test performance and limited number of students pursuing STEM degrees. Despite this investment, attitudes toward STEM have not notably changed. The goal of this project was to determine students' attitudes toward STEM in response to a previously established scientific outreach event. This event was used to address three common goals in STEM outreach: STEM literacy, diversity and inclusion, and career preparedness. We found there was a notable difference in the attitudes toward scientific activities and interest in pursuing a "Science Career" after participation in this event. Strikingly, interest in hypothesis development, the keystone of all STEM disciplines, was the least liked of all the activities offered during the event. Our data suggest that events designed to enhance interest in pursuing a STEM career may benefit from different elements compared with events designed to increase understanding of STEM literacy concepts, such as hypothesis development.

Transition to marine ice cliff instability controlled by ice thickness gradients and velocity.

Portions of ice sheets grounded deep beneath sea level can disintegrate if tall ice cliffs at the ice-ocean boundary start to collapse under their own weight. This process, called marine ice cliff instability, could lead to catastrophic retreat of sections of West Antarctica on decadal-to-century time scales. Here we use a model that resolves flow and failure of ice to show that dynamic thinning can slow or stabilize cliff retreat, but when ice thickness increases rapidly upstream from the ice cliff, there is a transition to catastrophic collapse. However, even if vulnerable locations like Thwaites Glacier start to collapse, small resistive forces from sea-ice and calved debris can slow down or arrest retreat, reducing the potential for sustained ice sheet collapse.

Time-resolved thermally induced aberrations in a flash-lamp pumped Nd:Glass disk amplifier using a 2 × 2 position sensitive detector array.

A novel technique of measuring the prompt, thermally induced wave-front aberrations in a large aperture flash-lamp pumped Nd3+ glass disk amplifier is presented. Implementing a 2 × 2 lens array and a 2 × 2 position sensitive detector array as a diagnostic system, the wave-front profile was successfully reconstructed for the first five Zernike terms for a temporal window of 8.5 ms.

Characterization of the first Batrachochytrium dendrobatidis isolate from the Colombian Andes, an amphibian biodiversity hotspot.

The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd), constitutes a significant threat to more than 790 amphibian species occurring in Colombia. To date there is no molecular or morphological description of strains infecting Colombian populations. Here we report the genetic and morphological characterization of the first Colombian isolate of Bd (strain EV001). Our goals were threefold: (1) to characterize the morphology of EV001 using light and scanning electron microscopy, (2) to genotype this strain by direct sequencing of 17 polymorphic nuclear markers developed previously, and (3) to compare our findings with published reports on strains from other areas of the globe. We found that EV001 is morphologically consistent with previously described strains. Multi-locus genotyping suggested that EV001 is grouped genetically with Panamanian strains and is most similar to strain JEL203 isolated from a captive individual. This finding fills an important gap in our knowledge of Neotropical strains of Bd and provides a baseline for further evolutionary and functional analyses.

Huge populations and old species of Costa Rican and Panamanian dirt frogs inferred from mitochondrial and nuclear gene sequences.

Molecular genetic data were used to investigate population sizes and ages of Eleutherodactylus (Anura: Leptodactylidae), a species-rich group of small leaf-litter frogs endemic to Central America. Population genetic structure and divergence was investigated for four closely related species surveyed across nine localities in Costa Rica and Panama. DNA sequence data were collected from a mitochondrial gene (ND2) and a nuclear gene (c-myc). Phylogenetic analyses yielded concordant results between loci, with reciprocal monophyly of mitochondrial DNA haplotypes for all species and of c-myc haplotypes for three of the four species. Estimates of genetic differentiation among populations (FST) based upon mitochondrial data were always higher than nuclear-based FST estimates, even after correcting for the expected fourfold lower effective population size (Ne) of the mitochondrial genome. Comparing within-population variation and the relative mutation rates of the two genes revealed that the Ne of the mitochondrial genome was 15-fold lower than the estimate of the nuclear genome based on c-myc. Nuclear FST estimates were approximately 0 for the most proximal pairs of populations, but ranged from 0.5 to 1.0 for all other pairs, even within the same nominal species. The nuclear locus yielded estimates of Ne within localities on the order of 105. This value is two to three orders of magnitude larger than any previous Ne estimate from frogs, but is nonetheless consistent with published demographic data. Applying a molecular clock model suggested that morphologically indistinguishable populations within one species may be 107 years old. These results demonstrate that even a geologically young and dynamic region of the tropics can support very old lineages that harbour great levels of genetic diversity within populations. The association of high nucleotide diversity within populations, large divergence between populations, and high species diversity is also discussed in light of neutral community models.

Mechanism of calcium and magnesium translocation in acute pancreatitis: a temporal correlation between hypocalcemia and membrane-mediated excessive intracellular calcium accumulation in soft tissues.

Hypocalcemia frequently occurs in acute pancreatitis (AP), but its pathogenesis remains unknown. Since AP is often accompanied by acute alteration in the structure and function of cellular membranes, we investigated whether hypocalcemia associated with AP can be explained by acute translocation of Ca from extracellular to intracellular compartments. AP was induced in dogs by injection of autologous bile into the pancreatic duct, and in rats by controlled infusion of artificial bile containing Na-taurochlorate, Keflin, and trypsin into the cannulated bile duct. Plasma Ca, Mg, amylase, and PTH concentrations were determined in the serial samples. Tissue [Ca] and [Mg] were determined in pancreas, liver, kidney, and abdominal wall muscle biopsies obtained immediately before and 24 h after induction of AP in dogs or 2 h following induction of AP in rats to evaluate the temporal correlation between hypocalcemia and excessive intracellular Ca accumulation in soft tissues. Hypocalcemia (p less than 0.001) and hyperamylasemia (p less than 0.01) occurred within 6 h of AP in dogs, and persisted throughout. Plasma [Mg] was lowered and PTH activity was elevated at 6 and 18 h, and returned to a near normal level by 24 h. Concomitant with persisting hypocalcemia and lower ultrafilterable plasma [Ca2+], tissue [Ca] was significantly elevated in pancreas (71%), liver (24%), and abdominal muscle (112%), but was depleted in kidney by 25%. Pancreas biopsy following AP revealed histological signs of fulminant pancreatitis. [Mg] was depleted only in the pancreas (18%) and remained unaltered in other tissues. No significant changes were noted in the sham-operated animals. The observed temporal correlation between profound hypocalcemia and acute excessive intracellular Ca accumulation in soft tissues strongly suggests that hypocalcemia in AP may be precipitated by leaky-plasma-membrane-mediated excessive intracellular Ca accumulation. Similar data together with significantly reduced cellular energy charge (p less than 0.01) obtained from AP rats provided additional support to our hypothesis.

Excessive intracellular zinc accumulation in cardiac and skeletal muscles of dystrophic hamsters.

Zinc has been reported to be important in protein synthesis, collagen crosslinking, membrane structure and function, cellular necrosis, muscle glycolysis, and cardiac dysfunction. As all these processes are affected by muscular dystrophy, we studied the Zn concentrations in the cardiac and skeletal muscles of 7-month-old male dystrophic hamsters with advanced hypertrophic cardiomyopathy. Age- and sex-matched normal hamsters served as controls. Calcium, magnesium, and copper concentrations were also measured in the dystrophic and normal tissues. Flame atomic absorption spectrophotometry was used for mineral quantitation of the nitric acid tissue extracts. Zn concentrations in the myocardium (P less than 0.002), diaphragm (P less than 0.005), and rectus femoris muscles (P less than 0.001) were significantly elevated with concomitant elevations of Ca in dystrophic compared with normal hamsters. Although no appreciable changes in Cu or Mg concentrations were noted in the myocardium, slight depletions of Cu in the dystrophic diaphragm (P less than 0.025) and Mg in the dystrophic rectus femoris (P less than 0.05) were present. The intracellular Zn and Ca accumulations in the cardiac and skeletal muscles of dystrophic hamsters correlated with other dystrophic features such as increased rates of protein synthesis, significant myocardial enlargement, characteristic electrocardiographic and mechanophysiologic abnormalities, and classical histopathologic changes. We hypothesize that Zn2+ may be cotransported with Ca2+ across the cellular membrane or substituted for Ca2+ in certain pathways. These mechanisms may be affected by the high-energy ATP-pump and/or the sodium-potassium exchange system at the cellular level. Our observations suggest a possible pathogenetic involvement of Zn in muscular dystrophy which may be associated with an accelerated effort by the cellular system to repair the damaged cardiac and skeletal muscles.

Electrocardiographic, biochemical, and morphologic abnormalities in dystrophic hamsters with cardiomyopathy.

Electrocardiographic (EKG) changes were investigated in 7-month-old dystrophic hamsters (DH) with cardiomyopathy and were correlated with biochemical and histologic aberrations. Abnormally tall R-I and R-aVL amplitudes, deep S-III and S-aVR waves, and elongated PR-I, QT-I, and QRS-I intervals (all at P less than 0.0001) were noted in DH compared with normal hamsters. These EKG changes are similar to those seen in Duchenne muscular dystrophy (DMD) and support cardiac hypertrophy (P less than 0.001) in DH. Excessive intracellular calcium accumulation in the heart (P less than 0.0001), diaphragm (P less than 0.001), and rectus femoris (P less than 0.05), and elevated plasma creatine kinase concentrations (P less than 0.001) were also noted in DH. Histopathology in the cardiac and skeletal muscles of DH included fatty infiltration, centronucleation, and sporadic necrosis with calcium deposition. Observed EKG abnormalities, biochemical alterations, and histological aberrations in the cardiac and skeletal muscles of DH are strikingly similar to those reported in DMD and thus substantiate the relevance of DH as a suitable model for the study of muscular dystrophy and cardiac hypertrophy.

Small bowel obstruction from an antacid bezoar: a ranitidine-antacid interaction?

A 63-year-old man had an acute small bowel obstruction while being treated with ranitidine and self-prescribed antacid. On exploration, a firm mass, chemically similar to the ingested antacid, was found impacted in the terminal ileum. We believe the effect of ranitidine on gastric secretory volume was the cause of the antacid concretion.

Biliary excretion of aluminum in aluminum osteodystrophy with liver disease.

Two patients with chronic liver disease developed elevated serum aluminum concentrations and biopsy-proven osteodystrophy. Neither patient had chronic renal failure but both had received aluminum-containing antacids for long periods. We measured biliary and urinary aluminum excretion during antacid loading in patients with normal liver function. Our studies show that biliary excretion is an important route of elimination of orally absorbed aluminum, and we suggest that long-term antacid therapy in patients with severe liver disease be monitored with periodic serum and urinary aluminum determinations to avoid aluminum osteodystrophy.

Improved presentation of data in a urodynamics clinic by use of a microcomputer.

A microcomputer system is described for the collection, analysis and printing of the physiological data gathered during a urodynamic investigation. Examples are given of the results obtained from such a system.

Soft tissue calcium and magnesium content in acute pancreatitis in the dog: calcium accumulation, a mechanism for hypocalcemia in acute pancreatitis.

The mechanism of hypocalcemia in acute pancreatitis remains unknown despite continued investigative work over the past several decades. Because acute pancreatitis is accompanied by multiple systemic manifestations and alterations of plasma membranes, the possibility that an abnormal translocation of calcium from extracellular to intracellular compartments could play a role in hypocalcemia of acute pancreatitis was investigated in dogs. Acute pancreatitis was induced by injecting bile into the pancreatic duct. Plasma calcium, magnesium, and amylase concentrations were determined. Calcium and magnesium contents were also measured in biopsy specimens of pancreas, liver, skeletal muscle, and kidney before and after induction of acute pancreatitis. As expected, hypocalcemia and hyperamylasemia occurred 6 hours after induction of pancreatitis, and persisted throughout the experiment, 13 to 25 hours. Plasma magnesium concentration fell at 6 and 18 hours, and returned to an almost normal level by the end of the study. A significant elevation in calcium content of pancreas (71%), liver (24%), and muscle (112%), and 25% reduction of calcium in kidney were observed in dogs with histologic signs of pancreatitis. However, tissue magnesium concentration fell in pancreas (18%) but remained unchanged in the other tissues investigated. No significant changes in any variables were detected in sham-operated animals. In another group of dogs in which the accessory pancreatic duct was not occluded when bile was injected, the histologic lesions were extremely mild, although the plasma calcium concentration and the pancreatic calcium and magnesium contents were altered just as much as in the severely affected dogs. Data suggest that the hypocalcemia of acute pancreatitis may be the result, at least in part, of accumulation of calcium in soft tissues. The decreased calcium content in kidney could be related to hypocalcemia.(ABSTRACT TRUNCATED AT 250 WORDS)

A force sensor and peak-reading recorder for measurement of cervical dilatation force.

Earlier dilatation force-sensing transducers, when subjected to side loads, suffered frictional losses which affected their accuracy. This new instrument incorporates a thermal-writing chart recorder and a digital readout of the peak force during dilatation of the cervix.