Showing 1971 - 1980 of 5713 Items
Construction and validation of UV-C decontamination cabinets for filtering facepiece respirators: Comment
Date: 2021-07-20
Creator: Anant Agrawal, Joyce Bor, Dale Syphers
Access: Open access
- In their September 2020 paper [Appl. Opt.59, 7585 (2020)], Purschke et al . report UV-C transmittance measurements of N95 filtering facepiece respirators (FFRs), including the 3M 1860, which is one of the most widely used FFRs.We have also measured the transmittance of this FFRin our two separate laboratories with multiple FFR samples, and we have obtained transmittance values similar to one another, but very different from what Purschke et al . reported for two of the four FFR layers.
Cubic curves from matrix models and generalized Konishi anomalies
Date: 2003-08-01
Creator: Stephen G. Naculich, Howard J. Schnitzer, Niclas Wyllard
Access: Open access
- We study the matrix model/gauge theory connection for three different N =1 models: U(N) × U(N) with matter in bifundamental representations, U(N) with matter in the symmetric representation, and U (N) with matter in the antisymmetric representation. Using Ward identities, we explicitly show that the loop equations of the matrix models lead to cubic algebraic curves. We then establish the equivalence of the matrix model and gauge theory descriptions in two ways. First, we derive generalized Konishi anomaly equations in the gauge theories, showing that they are identical to the matrix-model equations. Second, we use a perturbative superspace analysis to establish the relation between the gauge theories and the matrix models. We find that the gauge coupling matrix for U (N) with matter in the symmetric or antisymmetric representations is not given by the second derivative of the matrix-model free energy. However, the matrix-model prescription can be modified to give the gauge coupling matrix. © SISSA/ISAS 2003.
Art of John Sloan, 1871-1951: A Loan Exhibition and an Introductory Display of Paintings in the Hamlin Bequest to Bowdoin College
Date: 1962-01-01
Access: Open access
- Exhibition catalogue for Bowdoin College Museum of Art, January 20-February 28, 1962.
Alongside Despair: Signs of Life on the River des Peres
Date: 2020-01-01
Creator: Marina Henke
Access: Open access
- This River des Peres is a partially enclosed river which runs through St. Louis, Missouri. Used since prior to the city’s founding, the des Peres has gone through two considerable engineering projects: one in 1901 in light of the World’s Fair, and one in 1923, which encapsulated more than half of the river and placed nearly five miles of it underground. Presently, the des Peres constitutes the backbone of the sanitary and sewer system of St. Louis city and county. Ultimately, the river offers a broad meditation on what it means to live around and in a “natural” waterway that is simultaneously not natural at all. Themes of St. Louis are equally reflected in the river: of environmental racism, of Midwestern decline, and of urban decay and renewal. Additionally, those who interact with the river prove a broad cast of characters. Through using a selection of interviews with locals, alongside an engagement with the work of contemporary poet Donald Finkel, this piece of creative nonfiction explores the multiplicity, and ultimately the value, of distorted natural spaces.
Mercury in the snow and firn at Summit Station, Central Greenland, and implications for the study of past atmospheric mercury levels
Date: 2008-06-30
Creator: X. Faïn, C. P. Ferrari, A. Dommergue, M. Albert, M., Battle, L. Arnaud, J. M. Barnola, W. Cairns, C. Barbante, C. Boutron
Access: Open access
- Gaseous Elemental Mercury (Hg° or GEM) was investigated at Summit Station, Greenland, in the interstitial air extracted from the perennial snowpack (firn) at depths ranging from the surface to 30 m, during summer 2005 and spring 2006. Photolytic production and destruction of Hg° were observed close to the snow surface during summer 2005 and spring 2006, and we observed dark oxidation of GEM up to 270 cm depth in June 2006. Photochemical transformation of gaseous elemental mercury resulted in diel variations in the concentrations of this gas in the near-surface interstitial air, but destruction of Hg° was predominant in June, and production was the main process in July. This seasonal evolution of the chemical mechanisms involving gaseous elemental mercury produces a signal that propagates downward through the firn air, but is unobservably small below 15 m in depth. As a consequence, multi-annual averaged records of GEM concentration should be well preserved in deep firn air at depths below 15 m, and available for the reconstruction of the past atmospheric history of GEM over the last decades.
Localization of DNA sequences promoting RNA polymerase I activity in Drosophila
Date: 1983-01-01
Creator: B. D. Kohorn, P. M.M. Rae
Access: Open access
Resonance in the menstrual cycle: A new model of the LH surge
Date: 2003-01-01
Creator: Mary Lou Zeeman, W. Weckesser, D. Gokhman
Access: Open access
- In vertebrates, ovulation is triggered by a surge of LH from the pituitary. The precise mechanism by which rising oestradiol concentrations initiate the LH surge in the human menstrual cycle remains a fundamental open question of reproductive biology. It is well known that sampling of serum LH on a time scale of minutes reveals pulsatile release from the pituitary in response to pulses of gonadotrophin releasing hormone from the hypothalamus. The LH pulse frequency and amplitude vary considerably over the cycle, with the highest frequency and amplitude at the midcycle surge. Here a new mathematical model is presented of the pituitary as a damped oscillator (pulse generator) driven by the hypothalamus. The model LH surge is consistent with LH data on the time scales of both minutes and days. The model is used to explain the surprising pulse frequency characteristics required to treat human infertility disorders such as Kallmann's syndrome, and new experimental predictions are made.