Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations

We studied bright umbral dots (UDs) detected in a moderate size sunspot and compared their statistical properties to recent MHD models. The study is based on high resolution data recorded by the New Solar Telescope at the Big Bear Solar Observatory and 3D MHD simulations of sunspots. Observed UDs, living longer than 150 s, were detected and tracked in a 46 min long data set, using an automatic detection code. Total 1553 (620) UDs were detected in the photospheric (low chromospheric) data. Our main findings are: i) none of the analyzed UDs is precisely circular, ii) the diameter-intensity relationship only holds in bright umbral areas, and iii) UD velocities are inversely related to their lifetime. While nearly all photospheric UDs can be identified in the low chromospheric images, some small closely spaced UDs appear in the low chromosphere as a single cluster. Slow moving and long living UDs seem to exist in both the low chromosphere and photosphere, while fast moving and short living UDs are mainly detected in the photospheric images. Comparison to the 3D MHD simulations showed that both types of UDs display, on average, very similar statistical characteristics. However, i) the average number of observed UDs per unit area is smaller than that of the model UDs, and ii) on average, the diameter of model UDs is slightly larger than that of observed ones.Comment: Accepted by the AP

A Phase Space Approach to Gravitational Enropy

We examine the definition S = ln Omega as a candidate "gravitational entropy" function. We calculate its behavior for gravitationl and density perturbations in closed, open and flat cosmologies and find that in all cases it increases monotonically. Using the formalism to calculate the gravitational entropy produced during inflation gives the canonical answer. We compare the behavior of S with the behavior of the square of the Weyl tensor. Applying the formalism to black holes has proven more problematical.Comment: Talk delivered at South African Relativistic Cosmology Symposium, Feb 1999. Some new results over Rothman and Anninos 97. To appear in GRG, 17 page

On the evolution of a large class of inhomogeneous scalar field cosmologies

The asymptotic behaviour of a family of inhomogeneous scalar field cosmologies with exponential potential is studied. By introducing new variables we can perform an almost complete analysis of the evolution of these cosmologies. Unlike the homogeneous case (Bianchi type solutions), when k^2<2 the models do not isotropize due to the presence of the inhomogeneitiesComment: 23 pages, 1 figure. Submitted to Classical and Quantum Gravit

Volume 54 (2022)

The 2022 edition of The Broad River Review was edited by C. V. Davis, Meredith Bridges, Sarah Goode, Sarianna Miranda-Rosado, and Hannah Travis. COVER PHOTOGRAPHY: Lex Lucius, Majestic Horses: Pancho Close-Ups 1 & 2 THE 2022 RASH AWARD IN FICTION: Maureen Sherbondy, Rules of the Rich THE 2022 RASH AWARD IN POETRY: Stephen Benz, Uncle Jerry, Missing in Action THE 2022 FOOTHILLS POETRY AWARD: Neha Patel, Too Close to the Lights THE 2022 J. CALVIN KOONTS POETRY AWARD: Hannah Ray, Aubade for the Boatman POETRY: Jeffrey Alfier, Downcoast at Hampton Roads; George Bandy, Counting Back; Tina Barr, Still Life With Fruit Dish; Roy Bentley, (Sometimes I Feel) Like a Red-Collared Dog; Peter Bergquist, Basements; Terry Hall Bodine, Paper Boats; Dorothy Howe Brooks, Wanderers; Kathleen Calby, Harvest of Ice; Camille Carter, Feet of Clay; Kenneth Chamlee, Random Hours I Look at the Clock; Douglas Cole, The Eeriness of the Nightwalk; Stephany L.N. Davis, The Unmoving; Laine Derr, Without You; Timothy Dodd, Marvel Exchange; Hollie Dugas, Self Portrait as a Swiss Army Knife; Alan Elyshevitz, The Art of Fire and Smoke; Robert Fillman, On Rembrandt’s A Lady and Gentleman in Black; Katherine Gaffney, Notre Dame, 1994; Daniel Ginsburg, Animator; Adrianna Gordey, Dorothy Gale Goes to the Beach; Patricia L. Hamilton, Idol Worship; Todd Heldt, Afternoons; Ann Howells, Graffiti; Rosa Lane, The Victorian Dissident; Mary Dean Lee, Woodstove; Mark Madigan, First Snow; Jessica Mehta, God, Mother; Ryan Nelson, Empty Nest; Cathlin Noonan, Setting the Record; Richard Parisio, The Last Man on Earth; J.C. Reilly, My Cajun Cousin Fabienne Advises on Marriage; Anna Laura Reeve, Flower Moon; Claire Scott, Still Life With Tennis Racquet; Maureen Sherbondy, Mother of Sons; William Snyder, Call Me Pain for a Little While Longer; Noel Sloboda, Motley; Matthew J. Spireng, Flight 5585, Bozeman to Chicago; Brett Thompson, Starlight; Lucinda Trew, God and All the Soldiers; Victoria Twomey, Paradise; Danielle Ann Verwers, October; Ann Weil, Sonnet While Waiting for the Hurricane; Bob Wickless, Words for Nikola Tesla; Kuo Zhang, From X-Small to X-Large FICTION: Glenn Armocida, Pinned; Terry Hall Bodine, The Burn; Jim Gish, The River of Light; Chad Gusler, Man of Sorrows; Annette Leavy, The Free Temple; Emily Mathis, Baddies; Kai Mawougbe, F3; Ray Morrison, The Man Who Got Away; Kelly Talbot, The Witch Woman; Randolph Thomas, Late Reunion; Hannah Wells, Or Something Like That Chris Wiberg, Juicebox; CREATIVE FICTION: Genalea Barker, Unless, Of Course, It Doesn’t; Timothy Caldwell, My Father’s Funeral; Miranda Campbell, The Saddest, Most Beautiful Place in Georgia; Evan Gurney, An Intruder in My House; Lucinda Trew, Mothers and Mirrors; Sara Watkins, The Child Who Ate Wordshttps://digitalcommons.gardner-webb.edu/brreview/1022/thumbnail.jp

Maximum Coronal Mass Ejection Speed as an Indicator of Solar and Geomagnetic Activities

We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions

Heat and sun related medical concerns in Australian led outdoor activities: a three-year prospective study

Active participation in the outdoors is beneficial for health and wellbeing. However, the impact of extreme weather, particularly heat, on safe participation is causing concern for organisations who lead these activities. Local mitigation strategies and acute management of heat- and sun-related illness (HSRI) are generally well understood by researchers and medical practitioners, however, cases continue to occur so further understanding of why this happens is required. This study aimed to identify the number, nature and contributory factors of HSRI in Australian led outdoor activities in order to seek opportunities for their prevention. This study presents a descriptive analysis of contributory factors to HSRI occurring during led outdoor activities. Cases were prospectively collected across 3 years (2014-2017) from a national Australian incident reporting system. Cases were included by identification of keywords linked with sun or heat exposure. From 2,015 incident cases, 48 cases were included: 25 termed heat stroke and 23 as “other adverse outcomes related to sun or heat.” One in three (35%) cases occurred during outdoor walking or running, and one in four occurred while camping. A total 146 contributory factors were identified. These factors were attributed to the activity participant (e.g. competence, decision making); equipment and resources (e.g. food/drink, dehydration); and environment (e.g. hot weather.). Mild to moderate HSRI was identifiable by signs/symptoms. Contributory factors were linked to the individual participant. Potentially, these factors could be mitigated through system focused approaches. Awareness of wider responsibility for preventing HSRI should be promoted across led outdoor activities

Two-dimensional hydrodynamic lattice-gas simulations of binary immiscible and ternary amphiphilic fluid flow through porous media

The behaviour of two dimensional binary and ternary amphiphilic fluids under flow conditions is investigated using a hydrodynamic lattice gas model. After the validation of the model in simple cases (Poiseuille flow, Darcy's law for single component fluids), attention is focussed on the properties of binary immiscible fluids in porous media. An extension of Darcy's law which explicitly admits a viscous coupling between the fluids is verified, and evidence of capillary effects are described. The influence of a third component, namely surfactant, is studied in the same context. Invasion simulations have also been performed. The effect of the applied force on the invasion process is reported. As the forcing level increases, the invasion process becomes faster and the residual oil saturation decreases. The introduction of surfactant in the invading phase during imbibition produces new phenomena, including emulsification and micellisation. At very low fluid forcing levels, this leads to the production of a low-resistance gel, which then slows down the progress of the invading fluid. At long times (beyond the water percolation threshold), the concentration of remaining oil within the porous medium is lowered by the action of surfactant, thus enhancing oil recovery. On the other hand, the introduction of surfactant in the invading phase during drainage simulations slows down the invasion process -- the invading fluid takes a more tortuous path to invade the porous medium -- and reduces the oil recovery (the residual oil saturation increases).Comment: 48 pages, 26 figures. Phys. Rev. E (in press