Problemas cuantitativos y comprensión de conceptos

Los docentes de química a nivel universitario usamos «problemas», habitualmente de tipo cuantitativo, para enseñar y para evaluar. En este trabajo ponemos en duda de que lo hagamos en forma eficaz. Se muestra, a partir de pruebas diagnósticas de pares de problemas (uno cuantitativo y otro cualitativo similar), que muchos estudiantes pueden resolver los problemas cuantitativos sin una adecuada comprensión conceptual.Chemistry professors at university level make use of «problems», usually of a quantitative type, to teach and evaluate. In this article we question the fact of whether they do it in an efficient way. From diagnostic test of pairs of problems (a quantitative and a similar qualitative one) it is shown that many students can solve quantitative problems without an appropriate conceptual comprehension

Dementia caregiving in spousal relationships: a dyadic perspective

Objectives: The number of couples facing a dementia diagnosis for one partner of the spousal dyad increases. Spousal caregiving can be a highly stressful experience associated with negative caregiver outcomes such as depression and poorer immune function. However, surprisingly little is known about how the illness and the required care effects patient’s well-being and relational changes experienced by afflicted couples. The aim of this study was to provide a literature review on how the dyadic perspective is taken into account and on how dementia effects both parts of the dyad. Methods: In order to outline findings about individual and dyadic well-being of affected couples, we conducted a literature search to review the three types of studies. First, studies focusing on one partner’s perspective, usually the perspective of the caregiver; second, studies including the caregiver’s and partially the care receiver’s view; third, studies directly referring to both partners’ perspectives. Results: The majority of studies neglect the individual with dementia by exclusively assessing caregiver variables or only indirectly including patients’ characteristics. Very few studies embrace dyadic and relational variables to execute how both partners experience the illness, spousal caregiving, and changes in the relationship. Despite the arguable validity of self reports of individuals with dementia, some studies demonstrated the usefulness of including both partners’ perspectives. Discussion: Results indicate the urgent need of integrating the perspective of the individual with dementia to improve the understanding of the effects of dementia caregiving

An analysis of the most distant catalogued open clusters -- Re-assessing fundamental parameters with Gaia EDR3 and ASteCA\texttt{ASteCA}

Several studies have been presented in the last few years applying some kind of automatic processing of data to estimate the fundamental parameters of open clusters. These parameters are later on employed in larger scale analyses, for example the structure of the Galaxy's spiral arms. The distance is one of the more straightforward parameters to estimate, yet enormous differences can still be found among published data. This is particularly true for open clusters located more than a few kpc away. We cross-matched several published catalogues and selected the twenty-five most distant open clusters ($>$9000 pc). We then performed a detailed analysis of their fundamental parameters, with emphasis on their distances, to determine the agreement between catalogues and our estimates.} Photometric and astrometric data from the Gaia EDR3 survey was employed. The data was processed with our own membership analysis code (pyUPMASK), and our package for automatic fundamental cluster's parameters estimation ($\texttt{ASteCA}$). We find differences in the estimated distances of up to several kpc between our results and those catalogued, even for the catalogues that show the best matches with $\texttt{ASteCA}$ values. Large differences are also found for the age estimates. As a by-product of the analysis we find that vd Bergh-Hagen 176 could be the open cluster with the largest heliocentric distance catalogued to date. Caution is thus strongly recommended when using catalogued parameters of open clusters to infer large-scale properties of the Galaxy, particularly for those located more than a few kpc away.Comment: Accepted for publication in A&

Etoposide and adriamycin containing combination chemotherapy (HOPE-Bleo) for relapsed Hodgkin's disease.

Forty-four patients with relapsed or resistant Hodgkin's disease were treated with adriamycin 40 mg m-2 i.v. on day 1, vincristine 1.4 mg m-2 i.v. on days 1 and 8, prednisolone 40 mg m-2 orally daily for 8 days, etoposide 200 mg m-2 orally daily for 4 days according to the nadir white cell count, and bleomycin 10 mg m-2 i.v. days 1 and 8 (HOPE-Bleo). Median age was 27 (range 12-71). When stage was considered according to all sites currently or previously involved by Hodgkin's disease (cumulative stage) 26 patients (59%) had stage IV, 13 (29%) stage III and five (11%) stage II disease; 33 (75%) had B symptoms. All patients had received previous chemotherapy and 18 (41%) had received two or more regimens. Twenty-six patients (59%) achieved CR and 10 (23%) PR; the median duration of CR was 22 months and median survival for all patients was 48 months. Eight patients remain in continuous CR; none of these had received extensive previous chemotherapy. Among the 19 patients who had relapsed from CR achieved by a single previous chemotherapy regimen, six (32%) achieved long CR on HOPE-Bleo. The regimen was generally well tolerated but the principal toxicity was myelosuppression. There were two toxic deaths, one due to neutropenic sepsis and the other due to acute peritonitis. The HOPE-Bleo regimen is an effective treatment for relapsed or resistant Hodgkin's disease, with a low probability of carcinogenesis and infertility. These factors suggest that HOPE-Bleo deserves further evaluation as primary treatment for Hodgkin's disease and very careful selection of relapsed patients for high dose salvage chemotherapy with bone marrow transplants must be exercised

Phase II study of docetaxel in combination with epirubicin and protracted venous infusion 5-fluorouracil (ETF) in patients with recurrent or metastatic breast cancer. A Yorkshire breast cancer research group study

This study was originally designed as a phase I/II study, with a dose escalation of docetaxel in combination with epirubicin 50 mg m⁻² and 5-fluorouracil (5-FU) 200 mg m⁻² day⁻¹. However, as dose escalation was not possible, the study is reported as a phase II study of the combination to assess response and toxicity. A total of 51 patients with locally advanced or metastatic breast cancer were treated on this phase II study, with doses of docetaxel 50 mg m⁻², epirubicin 50 mg m⁻² and infusional 5-FU 200 mg m⁻² day⁻¹ for 21 days. The main toxicity of this combination was neutropenia with 89% of patients having grade 3 and 4 neutropenia, and 39% of patients experiencing febrile neutropenia. Nonhaematological toxicity was mild. The overall response rate in the assessable patients was 64%, with median progression-free survival of 38 weeks, and median survival of 70 weeks. The ETF regimen was found to be toxic, and it was not possible to escalate the dose of docetaxel above the first dose level. This regimen has therefore not been taken any further, but as a development of this a new study is ongoing, combining 3-weekly epirubicin, weekly docetaxel and capecitabine, days 1-14

Sixteen overlooked open clusters in the fourth Galactic quadrant

Aims. This paper has two main objectives: (1) To determine the intrinsic properties of 16 faint and mostly unstudied open clusters in the poorly known sector of the Galaxy at 270\u25e6 12300\u25e6 to probe the Milky Way structure in future investigations. (2) To address previously reported systematics in Gaia DR2 parallaxes by comparing the cluster distances derived from photometry with those derived from parallaxes. Methods. Deep UBVI photometry of 16 open clusters was carried out. Observations were reduced and analyzed in an automatic way using the ASteCA package to obtain individual distances, reddening, masses, ages, and metallicities. Photometric distances were compared to those obtained from a Bayesian analysis of Gaia DR2 parallaxes. Results. Ten out of the sixteen clusters are true or highly probable open clusters. Two of them are quite young and follow the trace of the Carina Arm and the already detected warp. The remaining clusters are placed in the interarm zone between the Perseus and Carina Arms, as expected for older objects. We found that the cluster van den Berg-Hagen 85 is 7.5 7 109 yr old, which means that it is one of the oldest open clusters detected in our Galaxy so far. The relationship of these ten clusters with the Galaxy structure in the solar neighborhood is discussed. The comparison of distances from photometry and parallaxes data in turn reveals a variable level of disagreement. Conclusions. Various zero-point corrections for Gaia DR2 parallax data recently reported were considered for a comparison between photometry- and parallax-based distances. The results tend to improve with some of these corrections. Photometric distance analysis suggests an average correction of 3c+0.026 mas (to be added to the parallaxes). The correction may have a more intricate dependence on distance, but addressing this level of detail will require a larger cluster sample

Sea ice led to poleward-shifted winds at the Last Glacial Maximum: the influence of state dependency on CMIP5 and PMIP3 models

Latitudinal shifts in the Southern Ocean westerly wind jet could drive changes in the glacial to interglacial ocean CO2 inventory. However, whilst CMIP5 model results feature consistent future-warming jet shifts, there is considerable disagreement in deglacial-warming jet shifts. We find here that the dependence of pre-industrial (PI) to Last Glacial Maximum (LGM) jet shifts on PI jet position, or state dependency, explains less of the shifts in jet simulated by the models for the LGM compared with future-warming scenarios. State dependence is also weaker for intensity changes, compared to latitudinal shifts in the jet. Winter sea ice was considerably more extensive during the LGM. Changes in surface heat fluxes, due to this sea ice change, probably had a large impact on the jet. Models that both simulate realistically large expansions in sea ice and feature PI jets which are south of 50° S show an increase in wind speed around 55° S and can show a poleward shift in the jet between the PI and the LGM. However, models with the PI jet positioned equatorwards of around 47° S do not show this response: the sea ice edge is too far from the jet for it to respond. In models with accurately positioned PI jets, a +1° difference in the latitude of the sea ice edge tends to be associated with a −0.85° shift in the 850 hPa jet. However, it seems that around 5° of expansion of LGM sea ice is necessary to hold the jet in its PI position. Since the Gersonde et al. (2005) data support an expansion of more than 5°, this result suggests that a slight poleward shift and intensification was the most likely jet change between the PI and the LGM. Without the effect of sea ice, models simulate poleward-shifted westerlies in warming climates and equatorward-shifted westerlies in colder climates. However, the feedback of sea ice counters and reverses the equatorward trend in cooler climates so that the LGM winds were more likely to have also been shifted slightly poleward