The fundamental cycle of concept construction underlying various theoretical frameworks

In this paper, the development of mathematical concepts over time is considered. Particular reference is given to the shifting of attention from step-by-step procedures that are performed in time, to symbolism that can be manipulated as mental entities on paper and in the mind. The development is analysed using different theoretical perspectives, including the SOLO model and various theories of concept construction to reveal a fundamental cycle underlying the building of concepts that features widely in different ways of thinking that occurs throughout mathematical learning

Aql X-1 in Outburst and Quiescence

We present photometry and spectroscopy of the soft x-ray transient Aql X-1. Optical photometry during an active state shows a strong (0.6 mag peak-to-peak) modulation at a period of 19 hours. Infrared (K'-band) photometry during a quiescent state limits any ellipsoidal variations to <0.07 mag (peak-to-peak), which implies an inclination i<31 (90% limit). Spectroscopy in a quiescent state shows at most very small radial velocity variations, which implies a very low inclination of i<12 (90% limit). The low inclination is rather unexpected given the large photometric modulation seen in the active state. The upper limit to the equivalent width of the anomalous Li 6707A line is <0.3A, which is similar to the measured strength of this line in several other x-ray transients.Comment: Accepted for publication in ApJ, 12 pages, 5 figure

Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science

The Disk Detective citizen science project aims to find new stars with 22 micron excess emission from circumstellar dust using data from NASA's WISE mission. Initial cuts on the AllWISE catalog provide an input catalog of 277,686 sources. Volunteers then view images of each source online in 10 different bands to identify false-positives (galaxies, background stars, interstellar matter, image artifacts, etc.). Sources that survive this online vetting are followed up with spectroscopy on the FLWO Tillinghast telescope. This approach should allow us to unleash the full potential of WISE for finding new debris disks and protoplanetary disks. We announce a first list of 37 new disk candidates discovered by the project, and we describe our vetting and follow-up process. One of these systems appears to contain the first debris disk discovered around a star with a white dwarf companion: HD 74389. We also report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137, and HD 218546) and a new detection of 22 micron excess around a previously known debris disk host star, HD 22128.Comment: 50 pages, accepted for publication in the Astrophysical Journa

Hemoglobin A1c and Arterial and Ventricular Stiffness in Older Adults

Objective: Arterial and ventricular stiffening are characteristics of diabetes and aging which confer significant morbidity and mortality; advanced glycation endproducts (AGE) are implicated in this stiffening pathophysiology. We examined the association between HbA1c, an AGE, with arterial and ventricular stiffness measures in older individuals without diabetes. Research Design & Methods: Baseline HbA1c was measured in 830 participants free of diabetes defined by fasting glucose or medication use in the Cardiovascular Health Study, a population-based cohort study of adults aged ≥65 years. We performed cross-sectional analyses using baseline exam data including echocardiography, ankle and brachial blood pressure measurement, and carotid ultrasonography. We examined the adjusted associations between HbA1c and multiple arterial and ventricular stiffness measures by linear regression models and compared these results to the association of fasting glucose (FG) with like measures. Results: HbA1c was correlated with fasting and 2-hour postload glucose levels (r = 0.21; p<0.001 for both) and positively associated with greater body-mass index and black race. In adjusted models, HbA1c was not associated with any measure of arterial or ventricular stiffness, including pulse pressure (PP), carotid intima-media thickness, ankle-brachial index, end-arterial elastance, or left ventricular mass (LVM). FG levels were positively associated with systolic, diastolic and PP and LVM. Conclusions: In this sample of older adults without diabetes, HbA1c was not associated with arterial or ventricular stiffness measures, whereas FG levels were. The role of AGE in arterial and ventricular stiffness in older adults may be better assessed using alternate AGE markers

Etiology of Severe Non-malaria Febrile Illness in Northern Tanzania: A Prospective Cohort Study.

The syndrome of fever is a commonly presenting complaint among persons seeking healthcare in low-resource areas, yet the public health community has not approached fever in a comprehensive manner. In many areas, malaria is over-diagnosed, and patients without malaria have poor outcomes. We prospectively studied a cohort of 870 pediatric and adult febrile admissions to two hospitals in northern Tanzania over the period of one year using conventional standard diagnostic tests to establish fever etiology. Malaria was the clinical diagnosis for 528 (60.7%), but was the actual cause of fever in only 14 (1.6%). By contrast, bacterial, mycobacterial, and fungal bloodstream infections accounted for 85 (9.8%), 14 (1.6%), and 25 (2.9%) febrile admissions, respectively. Acute bacterial zoonoses were identified among 118 (26.2%) of febrile admissions; 16 (13.6%) had brucellosis, 40 (33.9%) leptospirosis, 24 (20.3%) had Q fever, 36 (30.5%) had spotted fever group rickettsioses, and 2 (1.8%) had typhus group rickettsioses. In addition, 55 (7.9%) participants had a confirmed acute arbovirus infection, all due to chikungunya. No patient had a bacterial zoonosis or an arbovirus infection included in the admission differential diagnosis. Malaria was uncommon and over-diagnosed, whereas invasive infections were underappreciated. Bacterial zoonoses and arbovirus infections were highly prevalent yet overlooked. An integrated approach to the syndrome of fever in resource-limited areas is needed to improve patient outcomes and to rationally target disease control efforts

Amenability of groups and GG-sets

This text surveys classical and recent results in the field of amenability of groups, from a combinatorial standpoint. It has served as the support of courses at the University of G\"ottingen and the \'Ecole Normale Sup\'erieure. The goals of the text are (1) to be as self-contained as possible, so as to serve as a good introduction for newcomers to the field; (2) to stress the use of combinatorial tools, in collaboration with functional analysis, probability etc., with discrete groups in focus; (3) to consider from the beginning the more general notion of amenable actions; (4) to describe recent classes of examples, and in particular groups acting on Cantor sets and topological full groups

Family history of mood disorder and characteristics of major depressive disorder: A STAR*D (sequenced treatment alternatives to relieve depression) study

Wstęp. Klinicyści rutynowo pytają pacjentów z depresją o występowanie chorób psychicznych w rodzinie. Nie wiadomo jednak, czy pacjenci, w których rodzinie występowały tego typu schorzenia różnią się od osób z negatywnym wywiadem rodzinnym w tym kierunku. W badaniu porównano cechy demograficzne i kliniczne dużej grupy pacjentów ambulatoryjnych zgłaszających się do lekarza z powodu depresji bez objawów psychotycznych. Pacjenci udzielili informacji na temat krewnych pierwszego stopnia chorujących na depresję lub chorobę afektywną dwubiegunową. Metody. Osoby poddane badaniu rekrutowano do wieloośrodkowego badania klinicznego - Sekwencyjne Alternatywy Terapeutyczne w Leczeniu Depresji (STAR*D, Sequenced Treatment Alternatives to Relieve Depression). Oceniono różnice w cechach klinicznych i demograficznych u pacjentów z dodatnim i ujemnym wywiadem rodzinnym w kierunku zaburzeń afektywnych, po skorygowaniu ich pod względem wieku, płci, rasy i grupy etnicznej. Wyniki. Wśród pacjentów z dodatnim wywiadem rodzinnym w kierunku zaburzeń afektywnych (n = 2265; 56,5%) przeważały kobiety; depresja rozpoczęła się u nich wcześniej niż u pacjentów z ujemnym wywiadem rodzinnym w kierunku zaburzeń afektywnych (n = 1740; 43,5%). Nie znaleziono znaczących różnic w zakresie objawów depresyjnych, nasilenia depresji, jej nawrotowości, podtypów choroby, czy też funkcjonowania w ciągu dnia. Wnioski. Kobiety 2-krotnie częściej niż mężczyźni zgłaszały występowanie zaburzeń afektywnych w rodzinie, dodatni wywiad rodzinny wiązał się z wcześniejszym wystąpieniem choroby u probanta. Młody wiek w chwili zachorowania na depresję wydaje się charakteryzować rodzinny (a co za tym idzie uwarunkowany genetycznie) podtyp depresji, co jest zgodne z wynikami wcześniejszych badań.Introduction. Clinicians routinely ask patients with major depressive disorder (MDD) about their family history. It is unknown, however, if patients who report a positive family history differ from those who do not. This study compared the demographic and clinical features of a large cohort of treatment-seeking outpatients with nonpsychotic MDD who reported that they did or did not have at least one firstdegree relative who had either MDD or bipolar disorder. Methods. Subjects were recruited for the STAR*D multicenter trial. Differences in demographic and clinical features for patients with and without a family history of mood disorders were assessed after correcting for age, sex, race, and ethnicity. Results. Patients with a family history of mood disorder (n = 2265; 56.5%) were more frequently women and had an earlier age of onset of depression, as compared to those without such a history (n = 1740; 43.5%). No meaningful differences were found in depressive symptoms, severity, recurrence, depressive subtype, or daily function. Conclusions. Women were twice as likely as men to report a positive family history of mood disorder, and a positive family history was associated with younger age of onset of MDD in the proband. Consistent with prior research, early age of onset appears to define a familial and, by extension, genetic subtype of major depressive disorder