Participation of Math Students in Online and Face-to-Face Hybrid Mathematics Instruction

Blended hybrid mathematics instruction offers the flexibility of online learning and the engagement of face-to-face interaction. However, research on student participation in these learning environments needs to be improved. This study investigated the dynamics of student participation, focusing on four key dimensions: conceptual understanding, mathematical communication, problem-solving, and critical thinking and analysis. A survey of 158 BS Mathematics students revealed that online learners tended to exhibit a higher level of conceptual understanding. At the same time, face-to-face interactions enhance problem-solving skills and stimulate more remarkable development of critical thinking and analytical abilities. Mathematical communication skills were somewhat constrained in both settings, with face-to-face students displaying slightly higher participation. These findings underscore the importance of considering the diverse dimensions of student participation when delivering online and hybrid mathematics courses. Educators should provide opportunities for students to hone and cultivate essential skills across online and face-to-face contexts, thus enriching their learning experience

Confirmation of SBS 1150+599A As An Extremely Metal-Poor Planetary Nebula

SBS 1150+599A is a blue stellar object at high galactic latitude discovered in the Second Byurakan Survey. New high-resolution images of SBS 1150+599A are presented, demonstrating that it is very likely to be an old planetary nebula in the galactic halo, as suggested by Tovmassian et al (2001). An H-alpha image taken with the WIYN 3.5-m telescope and its "tip/tilt" module reveals the diameter of the nebula to be 9.2", comparable to that estimated from spectra by Tovmassian et al. Lower limits to the central star temperature were derived using the Zanstra hydrogen and helium methods to determine that the star's effective temperature must be > 68,000K and that the nebula is optically thin. New spectra from the MMT and FLWO telescopes are presented, revealing the presence of strong [Ne V] lambda 3425, indicating that the central star temperature must be > 100,000K. With the revised diameter, new central star temperature, and an improved central star luminosity, we can constrain photoionization models for the nebula significantly better than before. Because the emission-line data set is sparse, the models are still not conclusive. Nevertheless, we confirm that this nebula is an extremely metal-poor planetary nebula, having a value for O/H that is less than 1/100 solar, and possibly as low as 1/500 solar.Comment: 19 pages, 6 figures. Accepted for publication in the Astronomical Journa

Hepatitis E Virus Antibodies in Patients with Chronic Liver Disease

In the United States, the seroprevalence rate for hepatitis E virus (HEV) is ≈20%. This study examined HEV seroprevalence in persons with and without chronic liver disease. Our data indicate that HEV seropositivity is high in patients with chronic liver disease and that HEV seroprevalence increases significantly with age

Photometry and Spectroscopy of KS Ursae Majoris during Superoutburst

We report photometric and spectroscopic observations of the SU UMa-type dwarf novae, KS Ursae Majoris, during its 2003 February superoutburst. Modulations with a period of $0.07017\pm0.00021$ day, which is 3.3% larger than the orbital period, have been found during the superoutburst and may be positive superhumps. A maximum trough-to-peak amplitude of around 0.3 magnitude is determined for this superhump. The spectra show broad, absorption-line profiles. The lines display blue and red troughs which alternate in depth. The radial velocity curve of the absorption wings of H$\beta$ has an amplitude of $40\pm11$ km s$^{-1}$ and a phase offset of $0.12\pm0.03$. The $\gamma$ velocity of the binary is $3\pm9$ km s$^{-1}$ and varies on an order of 50 km s$^{-1}$ from day to day. From another clear evidence for a precessing eccentric disk, we obtain a solution to an eccentric outer disk consistent with theoretical works, which demonstrates the validity of the relation between superhumps and tidal effects. The inner part of the disk is also eccentric as evidenced by asymmetric and symmetric wings in the lines. Therefore, the whole disk is eccentric and the variation of $\gamma$ velocity and the evolutionary asymmetric line profiles could be criterions for an precessing eccentric accretion disk.Comment: 12 pages, 8 figures, accpeted for publication in A

Catalog of Radio Galaxies with z>0.3. I:Construction of the Sample

The procedure of the construction of a sample of distant ($z>0.3$) radio galaxies using NED, SDSS, and CATS databases for further application in statistical tests is described. The sample is assumed to be cleaned from objects with quasar properties. Primary statistical analysis of the list is performed and the regression dependence of the spectral index on redshift is found.Comment: 9 pages, 6 figures, 2 table

Результаты комбинированного антиангиогенного воздействия на новообразованные сосуды роговицы. экспериментально-морфологическое исследование

Results of comparative experimental and morphological study of activity on corneal neovascularization in rabbit’s eye of photodynamic therapy with Photosense and antiangiogenic therapy with Avastin (bevacizumab) alone, and in its combination are represented. The treatment was performed in regimens: 1) photodynamic therapy with Photosense (single intravenous injection in dose of 0.3 mg/kg 72 h prior to laser irradiation, power density of irradiation 500 mW/cm2, wavelength 675 nm); 2) drug antiangiogenic therapy with Avastin (single subconjuctival introduction at dose of 1.25 mg); 3) photodynamic therapy with Photosense (in described regimen) in combination with subconjuctival introduction of Avastin at dose of 1.25 mg immediately prior to irradiation. Combined photodynamic therapy with antiangiogenic therapy allows to obtain almost complete occlusion in all regions of corneal neovascular bed with shorter time interval comparing with those for monoregimens. In case of blood flow retention in great vessels courses of combined modality treatment may be repeated. The absence of side-effects on surrounding tissues and the recovery of optical characteristics of cornea may allow to use this upcoming method in clinical practice. Приведены результаты сравнительного экспериментально-морфологического исследования влияния на новообразованные сосуды роговицы глаза кролика фотодинамической терапии с препаратом фотосенс и медикаментозной антиангиогенной терапии с препаратом авастин (бевацизумаб) в режиме монотерапии, а также их сочетанного применения. Лечение проводили в режимах: 1) фотодинамическая терапия с препаратом фотосенс (однократное внутривенное введение в дозе 0,3 мг/кг за 72 ч до лазерного облучения, плотность мощности лазерного облучения 500 мВт/см2, длина волны 675 нм); 2) медикаментозная анти- ангиогенная терапия с препаратом авастин (однократное субконьюнктивальное введение в дозе 1,25 мг); 3) фотодинамическая терапия с препаратом фотосенс (в указанном режиме) в сочетании с субконьюнктивальным введением препарата авастин в дозе 1,25 мг непосредственно перед проведением облучения. Показано, что при сочетанном применении фотодинамической и антиогенной терапии можно добиться практически полной окклюзии во всех отделах новообразованного сосудистого русла роговицы, причем в более короткий промежуток времени по сравнению со временем лечения в монорежимах. В случае сохранения кровотока в крупных магистральных сосудах возможно проведение повторных курсов комбинированного лечения. Отсутствие побочного воздействия на окружающие ткани и восстановление оптических свойств роговицы возможно позволит в перспективе использовать предложенный метод в клинической практике.

Superhumps in Cataclysmic Binaries. XXIV. Twenty More Dwarf Novae

We report precise measures of the orbital and superhump period in twenty more dwarf novae. For ten stars, we report new and confirmed spectroscopic periods - signifying the orbital period P_o - as well as the superhump period P_sh. These are GX Cas, HO Del, HS Vir, BC UMa, RZ Leo, KV Dra, KS UMa, TU Crt, QW Ser, and RZ Sge. For the remaining ten, we report a medley of P_o and P_sh measurements from photometry; most are new, with some confirmations of previous values. These are KV And, LL And, WX Cet, MM Hya, AO Oct, V2051 Oph, NY Ser, KK Tel, HV Vir, and RX J1155.4-5641. Periods, as usual, can be measured to high accuracy, and these are of special interest since they carry dynamical information about the binary. We still have not quite learned how to read the music, but a few things are clear. The fractional superhump excess epsilon [=(P_sh-P_o)/P_o] varies smoothly with P_o. The scatter of the points about that smooth curve is quite low, and can be used to limit the intrinsic scatter in M_1, the white dwarf mass, and the mass-radius relation of the secondary. The dispersion in M_1 does not exceed 24%, and the secondary-star radii scatter by no more than 11% from a fixed mass-radius relation. For the well-behaved part of epsilon(P_o) space, we estimate from superhump theory that the secondaries are 18+-6% larger than theoretical ZAMS stars. This affects some other testable predictions about the secondaries: at a fixed P_o, it suggests that the secondaries are (compared with ZAMS predictions) 40+-14% less massive, 12+-4% smaller, 19+-6% cooler, and less luminous by a factor 2.5(7). The presence of a well-defined mass-radius relation, reflected in a well-defined epsilon(P_o) relation, strongly limits effects of nuclear evolution in the secondaries.Comment: PDF, 62 pages, 7 tables, 21 figures; accepted, in press, to appear November 2003, PASP; more info at http://cba.phys.columbia.edu