Learning by Seeing by Doing: Arithmetic Word Problems

Learning by doing in pursuit of real-world goals has received much attention from education researchers but has been unevenly supported by mathematics education software at the elementary level, particularly as it involves arithmetic word problems. In this article, we give examples of doing-oriented tools that might promote children\u27s ability to see significant abstract structures in mathematical situations. The reflection necessary for such seeing is motivated by activities and contexts that emphasize affective and social aspects. Natural language, as a representation already familiar to children, is key in these activities, both as a means of mathematical expression and as a link between situations and various abstract representations. These tools support children\u27s ownership of a mathematical problem and its expression; remote sharing of problems and data; software interpretation of children\u27s own word problems; play with dynamically linked representations with attention to children\u27s prior connections; and systematic problem variation based on empirically determined level of difficulty

Terlipressin or norepinephrine in septic shock: do we have the answer?

Comment on Terlipressin versus norepinephrine as infusion in patients with septic shock: a multicentre, randomised, double-blinded trial. [Intensive Care Med. 2018

Wages, Benefits, Hours, Commuting Time, and License Renewal for Iowa Registered Nurses

The Iowa Board of Nursing licensing database for Registered Nurses (RNs) contains information on Registered Nurses who have renewed their licenses including age, race, gender, education, and location of employment.  It also contains comparable information on nurses who opted not to renew at the time of their last renewal. This report contains an analysis of the nurses’ characteristics that increase the likelihood of license renewal based on all useable information contained in the licensing database.  In addition, we randomly sampled subpopulations of nurses who had current licenses and nurses who had allowed their licenses to expire.  A survey of these nurses was analyzed to provide insights into the effects of individual wages, benefits, family income, family responsibilities, hours worked, and commuting time on the decision to work, work in nursing, and maintain a nursing license. Wages; workforce; benefits; labor force; nurses; health care

Candidates for asteroid dust trails

The contribution of different sources to the circumsolar dust cloud (known as the zodiacal cloud) can be deduced from diagnostic observations. We used the Spitzer Space Telescope to observe the diffuse thermal emission of the zodiacal cloud near the ecliptic. Several structures were identified in these observations, including previously known asteroid dust bands, which are thought to have been produced by recent asteroid collisions, and cometary trails. Interestingly, two of the detected dust trails, denoted t1 and t2 here, cannot be linked to any known comet. Trails t1 and t2 represent a much larger integrated brightness than all known cometary trails combined and may therefore be major contributors to the circumsolar dust cloud. We used our Spitzer observations to determine the orbits of these trails and were able to link them to two ("orphan" or type II) trails that were discovered by the Infrared Astronomical Satellite (IRAS) in 1983. The orbits of trails t1 and t2 that we determined by combining the Spitzer and IRAS data have semimajor axes, eccentricities, and inclinations like those of the main-belt asteroids. We therefore propose that trails t1 and t2 were produced by very recent (<~100 kyr old) collisional breakups of small, <~10 km diameter main-belt asteroids

Stiffening thermal membranes by cutting

Two-dimensional crystalline membranes have recently been realized experimentally in such systems as graphene and molybdenum disulfide, sparking a resurgence in interest in their statistical properties. Thermal fluctuations can significantly affect the effective mechanical properties of properly thermalized membranes, renormalizing both bending rigidity and elastic moduli so that in particular they become stiffer to bending than their bare bending rigidity would suggest. We use molecular dynamics simulations to examine how the mechanical behavior of thermalized two-dimensional clamped ribbons (cantilevers) depends on their precise topology and geometry. We find that a simple slit smooths roughness as measured by the variance of height fluctuations. This counterintuitive effect may be due to the counter-posed coupling of the lips of the slit to twist in the intact regions of the ribbon.Comment: 7 page

Biomarkers of Pediatric Brain Tumors

Background and Need for Novel Biomarkers: Brain tumors are the leading cause of death by solid tumors in children. Although improvements have been made in their radiological detection and treatment, our capacity to promptly diagnose pediatric brain tumors in their early stages remains limited. This contrasts several other cancers where serum biomarkers such as cancer antigen (CA) 19-9 and CA 125 facilitate early diagnosis and treatment. Aim: The aim of this article is to review the latest literature and highlight biomarkers which may be of clinical use in the common types of primary pediatric brain tumor. Methods: A PubMed search was performed to identify studies reporting biomarkers in the bodily fluids of pediatric patients with brain tumors. Details regarding the sample type [serum, cerebrospinal fluid (CSF), or urine], biomarkers analyzed, methodology, tumor type, and statistical significance were recorded. Results: A total of 12 manuscripts reporting 19 biomarkers in 367 patients vs. 397 controls were identified in the literature. Of the 19 biomarkers identified, 12 were isolated from CSF, 2 from serum, 3 from urine, and 2 from multiple bodily fluids. All but one study reported statistically significant differences in biomarker expression between patient and control groups. Conclusion: This review identifies a panel of novel biomarkers for pediatric brain tumors. It provides a platform for the further studies necessary to validate these biomarkers and, in addition, highlights several techniques through which new biomarkers can be discovered

Ceres' opposition effect observed by the Dawn framing camera

The surface reflectance of planetary regoliths may increase dramatically towards zero phase angle, a phenomenon known as the opposition effect (OE). Two physical processes that are thought to be the dominant contributors to the brightness surge are shadow hiding (SH) and coherent backscatter (CB). The occurrence of shadow hiding in planetary regoliths is self-evident, but it has proved difficult to unambiguously demonstrate CB from remote sensing observations. One prediction of CB theory is the wavelength dependence of the OE angular width. The Dawn spacecraft observed the OE on the surface of dwarf planet Ceres. We characterize the OE over the resolved surface, including the bright Cerealia Facula, and to find evidence for SH and/or CB. We analyze images of the Dawn framing camera by means of photometric modeling of the phase curve. We find that the OE of most of the investigated surface has very similar characteristics, with an enhancement factor of 1.4 and a FWHM of 3{\deg} (broad OE). A notable exception are the fresh ejecta of the Azacca crater, which display a very narrow brightness enhancement that is restricted to phase angles $< 0.5${\deg} (narrow OE); suggestively, this is in the range in which CB is thought to dominate. We do not find a wavelength dependence for the width of the broad OE, and lack the data to investigate the dependence for the narrow OE. The prediction of a wavelength-dependent CB width is rather ambiguous. The zero-phase observations allow us to determine Ceres' visible geometric albedo as $p_V = 0.094 \pm 0.005$. A comparison with other asteroids suggests that Ceres' broad OE is typical for an asteroid of its spectral type, with characteristics that are primarily linked to surface albedo. Our analysis suggests that CB may occur on the dark surface of Ceres in a highly localized fashion.Comment: Credit: Schr\"oder et al, A&A in press, 2018, reproduced with permission, \copyright ES

Technical Performance Reduces during the Extra-Time Period of Professional Soccer Match-Play

Despite the importance of extra-time in determining progression in specific soccer tournament matches, few studies have profiled the demands of 120-minutes of soccer match-play. With a specific focus on the extra-time period, and using a within-match approach, we examined the influence of prolonged durations of professional soccer match-play on markers of technical (i.e., skilled) performance. In 18 matches involving professional European teams played between 2010 and 2014, this retrospective study quantified the technical actions observed during eight 15-minute epochs (E1: 00:00–14:59 min, E2: 15:00-29:59 min, E3: 30:00-44:59 min, E4: 45:00-59:59 min, E5: 60:00-74:59 min, E6: 75:00-89:59 min, E7: 90:00-104:59 min, E8: 105:00-119:59 min). Analysis of players who completed the demands of the full 120 min of match-play revealed that the cumulative number of successful passes observed during E8 (61±23) was lower than E1-4 (E1: 88±23, P=0.001; E2: 77±21, P=0.005; E3: 79±18, P=0.001; E4: 80±21, P=0.001) and E7 (73±20, P=0.002). Similarly, the total number of passes made in E8 (71±25) was reduced when compared to E1 (102±22, P=0.001), E3 (91±19, P=0.002), E4 (93±22, P≤0.0005) and E7 (84±20, P=0.001). The cumulative number of successful dribbles reduced in E8 (9±4) when compared to E1 (14±4, P=0.001) and E3 (12±4, P≤0.0005) and the total time the ball was in play was less in E8 (504±61 s) compared to E1 (598±70 s, P≤0.0005). These results demonstrate that match-specific factors reduced particular indices of technical performance in the second half of extra-time. Interventions that seek to maintain skilled performance throughout extra-time warrant further investigation

Intra-tumor L-methionine level highly correlates with tumor size in both pancreatic cancer and melanoma patient-derived orthotopic xenograft (PDOX) nude-mouse models.

An excessive requirement for methionine (MET) for growth, termed MET dependence, appears to be a general metabolic defect in cancer. We have previously shown that cancer-cell growth can be selectively arrested by MET restriction such as with recombinant methioninase (rMETase). In the present study, we utilized patient-derived orthotopic xenograft (PDOX) nude mouse models with pancreatic cancer or melanoma to determine the relationship between intra-tumor MET level and tumor size. After the tumors grew to 100 mm3, the PDOX nude mice were divided into two groups: untreated control and treated with rMETase (100 units, i.p., 14 consecutive days). On day 14 from initiation of treatment, intra-tumor MET levels were measured and found to highly correlate with tumor volume, both in the pancreatic cancer PDOX (p&lt;0.0001, R2=0.89016) and melanoma PDOX (p&lt;0.0001, R2=0.88114). Tumors with low concentration of MET were smaller. The present results demonstrates that patient tumors are highly dependent on MET for growth and that rMETase effectively lowers tumor MET

Design of the Subpopulations and Intermediate Outcome Measures in COPD (SPIROMICS) AIR Study.

IntroductionPopulation-based epidemiological evidence suggests that exposure to ambient air pollutants increases hospitalisations and mortality from chronic obstructive pulmonary disease (COPD), but less is known about the impact of exposure to air pollutants on patient-reported outcomes, morbidity and progression of COPD.Methods and analysisThe Subpopulations and Intermediate Outcome Measures in COPD (SPIROMICS) Air Pollution Study (SPIROMICS AIR) was initiated in 2013 to investigate the relation between individual-level estimates of short-term and long-term air pollution exposures, day-to-day symptom variability and disease progression in individuals with COPD. SPIROMICS AIR builds on a multicentre study of smokers with COPD, supplementing it with state-of-the-art air pollution exposure assessments of fine particulate matter, oxides of nitrogen, ozone, sulfur dioxide and black carbon. In the parent study, approximately 3000 smokers with and without airflow obstruction are being followed for up to 3 years for the identification of intermediate biomarkers which predict disease progression. Subcohorts undergo daily symptom monitoring using comprehensive daily diaries. The air monitoring and modelling methods employed in SPIROMICS AIR will provide estimates of individual exposure that incorporate residence-specific infiltration characteristics and participant-specific time-activity patterns. The overarching study aim is to understand the health effects of short-term and long-term exposures to air pollution on COPD morbidity, including exacerbation risk, patient-reported outcomes and disease progression.Ethics and disseminationThe institutional review boards of all the participating institutions approved the study protocols. The results of the trial will be presented at national and international meetings and published in peer-reviewed journals