What jokes can tell us about arguments

Perelman teaches us that, unlike demonstrations, arguments cannot be reduced to or understood as closed systems. In some particular--but telling-- ways, arguments are like jokes. Telling a joke requires close attention to, e.g., appropriateness as re gards subjects, length (what details add or subtract from the humour), the extent of shared knowledge of both particulars and stereotypes, and whether it is possible to be ironic without being misunderstood. Thinking along these lines points up the futil ity of reducing either the invention or the evaluation of arguments to formal schemata

Neurochemistry of Attention-Deficit/Hyperactivity Disorder (ADHD)

There are numerous books about Attention-Deficit/Hyperactivity Disorder (ADHD) on the market. These books range from being very nontechnical, geared towards elementary educators and parents, to highly technical, geared towards medical and mental health professionals. To complicate matters further, the manner in which ADHD is defined and diagnosed has recently changed with the release of the DSM-V in 2013, which makes even relatively recent texts out-of-date. This Creative Inquiry project involves research into the most recent data on the neurochemistry behind what causes ADHD and comorbid conditions, as well as the neurochemistry of how drugs used to treat these conditions work to affect patient mental health. The goal of this project is to write and publish a book that begins with simple descriptions of these processes and builds to more technical language, providing parents and teachers with the ability to become experts in ADHD without a preexisting background in science

Posterior Reconstruction Before Anastomosis Improves the Anastomosis Time During Robot-Assisted Radical Prostatectomy

Posterior reconstruction prior to anastomosis decreased anastomotic time for robotic surgeons in training

Micro-Hall Magnetometry Studies of Thermally Assisted and Pure Quantum Tunneling in Single Molecule Magnet Mn12-Acetate

We have studied the crossover between thermally assisted and pure quantum tunneling in single crystals of high spin (S=10) uniaxial single molecule magnet Mn12-acetate using micro-Hall effect magnetometry. Magnetic hysteresis experiments have been used toinvestigate the energy levels that determine the magnetization reversal as a function of magnetic field and temperature. These experiments demonstrate that the crossover occurs in a narrow (~0.1 K) or broad (~1 K) temperature interval depending on the magnitude and direction of the applied field. For low external fields applied parallel to the easy axis, the energy levels that dominate the tunneling shift abruptly with temperature. In the presence of a transverse field and/or large longitudinal field these energy levels change with temperature more gradually. A comparison of our experimental results with model calculations of this crossover suggest that there are additional mechanisms that enhance the tunneling rate of low lying energy levels and broaden the crossover for small transverse fields.Comment: 5 pages, 5 figure

SN 2006bt: A Perplexing, Troublesome, and Possibly Misleading Type Ia Supernova

SN 2006bt displays characteristics unlike those of any other known Type Ia supernova (SN Ia). We present optical light curves and spectra of SN 2006bt which demonstrate the peculiar nature of this object. SN 2006bt has broad, slowly declining light curves indicative of a hot, high-luminosity SN, but lacks a prominent second maximum in the i band as do low-luminosity SNe Ia. Its spectra are similar to those of low-luminosity SNe Ia, containing features that are only present in cool SN photospheres. Light-curve fitting methods suggest that SN 2006bt is reddened by a significant amount of dust; however, it occurred in the outskirts of its early-type host galaxy and has no strong Na D absorption in any of its spectra, suggesting a negligible amount of host-galaxy dust absorption. C II is possibly detected in our pre-maximum spectra, but at a much lower velocity than other elements. The progenitor was likely very old, being a member of the halo population of a galaxy that shows no signs of recent star formation. SNe Ia have been very successfully modeled as a one-parameter family, and this is fundamental to their use as cosmological distance indicators. SN 2006bt is a challenge to that picture, yet its relatively normal light curves allowed SN 2006bt to be included in cosmological analyses. We generate mock SN Ia datasets which indicate that contamination by similar objects will both increase the scatter of a SN Ia Hubble diagram and systematically bias measurements of cosmological parameters. However, spectra and rest-frame i-band light curves should provide a definitive way to identify and eliminate such objects.Comment: ApJ, accepted. 13 pages, 13 figure

Limits on dust emission from z~5 LBGs and their local environments

We present 1.2mm MAMBO-2 observations of a field which is over-dense in Lyman Break Galaxies (LBGs) at z~5. The field includes seven spectroscopically-confirmed LBGs contained within a narrow (z=4.95+/-0.08) redshift range and an eighth at z=5.2. We do not detect any individual source to a limit of 1.6 mJy/beam (2*rms). When stacking the flux from the positions of all eight galaxies, we obtain a limit to the average 1.2 mm flux of these sources of 0.6mJy/beam. This limit is consistent with FIR imaging in other fields which are over-dense in UV-bright galaxies at z~5. Independently and combined, these limits constrain the FIR luminosity (8-1000 micron) to a typical z~5 LBG of LFIR<~3x10^11 Lsun, implying a dust mass of Mdust<~10^8 Msun (both assuming a grey body at 30K). This LFIR limit is an order of magnitude fainter than the LFIR of lower redshift sub-mm sources (z~1-3). We see no emission from any other sources within the field at the above level. While this is not unexpected given millimetre source counts, the clustered LBGs trace significantly over-dense large scale structure in the field at z = 4.95. The lack of any such detection in either this or the previous work, implies that massive, obscured star-forming galaxies may not always trace the same structures as over-densities of LBGs, at least on the length scale probed here. We briefly discuss the implications of these results for future observations with ALMA.Comment: 10 pages, 6 figures, MNRAS Accepte

Hubble Space Telescope studies of low-redshift Type Ia supernovae: Evolution with redshift and ultraviolet spectral trends

We present an analysis of the maximum light, near ultraviolet (NUV; 2900-5500 A) spectra of 32 low redshift (0.001<z<0.08) Type Ia supernovae (SNe Ia), obtained with the Hubble Space Telescope (HST). We combine this spectroscopic sample with high-quality gri light curves obtained with robotic telescopes to measure photometric parameters, such as stretch, optical colour, and brightness. By comparing our data to a comparable sample of SNe Ia at intermediate-z (0.4<z<0.9), we detect modest spectral evolution (3-sigma), in the sense that our mean low-z NUV spectrum has a depressed flux compared to its intermediate-z counterpart. We also see a strongly increased dispersion about the mean with decreasing wavelength, confirming the results of earlier surveys. These trends are consistent with changes in metallicity as predicted by contemporary SN Ia spectral models. We also examine the properties of various NUV spectral diagnostics in the individual spectra. We find a general correlation between stretch and the velocity (or position) of many NUV spectral features. In particular, we observe that higher stretch SNe have larger Ca II H&K velocities, that also correlate with host galaxy stellar mass. This latter trend is probably driven by the well-established correlation between stretch and stellar mass. We find no trends between UV spectral features and optical colour. Mean spectra constructed according to whether the SN has a positive or negative Hubble residual show very little difference at NUV wavelengths, indicating that the NUV evolution and variation we identify do not directly correlate with Hubble residuals. Our work confirms and strengthens earlier conclusions regarding the complex behaviour of SNe Ia in the NUV spectral region, but suggests the correlations we find are more useful in constraining progenitor models than improving the use of SNe Ia as cosmological probes.Comment: 22 pages, 14 figures, accepted in MNRAS with minor changes - Spectra are available on WISeREP, http://www.weizmann.ac.il/astrophysics/wiserep

Hybrid Bermudagrass Responses to Impaired Water Sources

Low-quality (i.e., impaired) water sources are commonly used to irrigate warm-season turfgrass landscapes as a result of limited supplies of potable water sources. Currently, there is great need to define the impacts of impaired water sources on turfgrass water consumption, growth, and quality. The objectives of this study were to characterize actual evaporation (ETa), clipping production, and quality of three hybrid bermudagrass varieties [‘TifTuf’, ‘Tifway’, and ‘Midiron’; Cynodon dactylon (L.) Pers. × C. traansvalensis Burtt Davy] grown under three water sources [reverse osmosis (RO), local well, and recycled], each supplied at full irrigation levels (1.0 × ETa) over two 8-week study periods. When pooling across water source and date, TifTuf maintained the highest visual quality and normalized difference vegetation index (NDVI) compared with both Midiron and Tifway. This was accompanied by a greater daily ETa rate, clipping production, and water use efficiency (WUE) compared with Midiron in both studies. When pooling across variety and date, daily ETa of turfgrass receiving recycled water was 5% to 10% less than those receiving the local well or RO water. In addition, turfgrasses receiving local well water held the greatest visual quality and NDVI compared with those receiving either RO water in the summer study. Visual quality and NDVI were also less in turfgrasses receiving RO water compared with those receiving local well or recycled water in the fall. Despite turfgrasses having a lower ETa under recycled water in both study periods, these plants had significantly greater clipping production compared with RO water in the summer. Also, clipping production under recycled water did not differ significantly from the other two sources in the fall study. Furthermoe, in both studies, WUE was similar for turfgrasses receiving recycled water compared with those receiving RO or local well water. Results demonstrated that irrigation water quality influences critical factors for hybrid bermudagrass growth and that considerable variability exists among three commercially available varieties for evapotranspiration rates, quality, and clipping production

Nearby Supernova Factory Observations of SN 2007if: First Total Mass Measurement of a Super-Chandrasekhar-Mass Progenitor

We present photometric and spectroscopic observations of SN 2007if, an overluminous (M_V = -20.4), red (B-V = 0.16 at B-band maximum), slow-rising (t_rise = 24 days) type Ia supernova in a very faint (M_g = -14.10) host galaxy. A spectrum at 5 days past B-band maximum light is a direct match to the super-Chandrasekhar-mass candidate SN Ia 2003fg, showing Si II and C II at ~9000 km/s. A high signal-to-noise co-addition of the SN spectral time series reveals no Na I D absorption, suggesting negligible reddening in the host galaxy, and the late-time color evolution has the same slope as the Lira relation for normal SNe Ia. The ejecta appear to be well mixed, with no strong maximum in I-band and a diversity of iron-peak lines appearing in near-maximum-light spectra. SN2007 if also displays a plateau in the Si II velocity extending as late as +10 days, which we interpret as evidence for an overdense shell in the SN ejecta. We calculate the bolometric light curve of the SN and use it and the \ion{Si}{2} velocity evolution to constrain the mass of the shell and the underlying SN ejecta, and demonstrate that SN2007 if is strongly inconsistent with a Chandrasekhar-mass scenario. Within the context of a "tamped detonation" model appropriate for double-degenerate mergers, and assuming no host extinction, we estimate the total mass of the system to be 2.4 +/- 0.2 solar masses, with 1.6 +/- 0.1 solar masses of nickel-56 and with 0.3-0.5 solar masses in the form of an envelope of unburned carbon/oxygen. Our modeling demonstrates that the kinematics of shell entrainment provide a more efficient mechanism than incomplete nuclear burning for producing the low velocities typical of super-Chandrasekhar-mass SNeIa.Comment: 23 pages, 13 figures, 4 tables, emulateapj format; v2 fixed some typos and added a reference; v3 included minor copy-editing changes + fixed typos in Figure 9, Table 4; accepted to Ap

The Subluminous and Peculiar Type Ia Supernova PTF09dav

PTF09dav is a peculiar subluminous type Ia supernova (SN) discovered by the Palomar Transient Factory (PTF). Spectroscopically, it appears superficially similar to the class of subluminous SN1991bg-like SNe, but it has several unusual features which make it stand out from this population. Its peak luminosity is fainter than any previously discovered SN1991bg-like SN Ia (M_B -15.5), but without the unusually red optical colors expected if the faint luminosity were due to extinction. The photospheric optical spectra have very unusual strong lines of Sc II and Mg I, with possible Sr II, together with stronger than average Ti II and low velocities of ~6000 km/s. The host galaxy of PTF09dav is ambiguous. The SN lies either on the extreme outskirts (~41kpc) of a spiral galaxy, or in an very faint (M_R>-12.8) dwarf galaxy, unlike other 1991bg-like SNe which are invariably associated with massive, old stellar populations. PTF09dav is also an outlier on the light-curve-width--luminosity and color--luminosity relations derived for other sub-luminous SNe Ia. The inferred 56Ni mass is small (0.019+/-0.003Msun), as is the estimated ejecta mass of 0.36Msun. Taken together, these properties make PTF09dav a remarkable event. We discuss various physical models that could explain PTF09dav. Helium shell detonation or deflagration on the surface of a CO white-dwarf can explain some of the features of PTF09dav, including the presence of Sc and the low photospheric velocities, but the observed Si and Mg are not predicted to be very abundant in these models. We conclude that no single model is currently capable of explaining all of the observed signatures of PTF09dav.Comment: Accepted for publication in Ap