How well can regional fluxes be derived from smaller-scale estimates?

Regional surface fluxes are essential lower boundary conditions for large scale numerical weather and climate models and are the elements of global budgets of important trace gases. Surface properties affecting the exchange of heat, moisture, momentum and trace gases vary with length scales from one meter to hundreds of km. A classical difficulty is that fluxes have been measured directly only at points or along lines. The process of scaling up observations limited in space and/or time to represent larger areas was done by assigning properties to surface classes and combining estimated or calculated fluxes using an area weighted average. It is not clear that a simple area weighted average is sufficient to produce the large scale from the small scale, chiefly due to the effect of internal boundary layers, nor is it known how important the uncertainty is to large scale model outcomes. Simultaneous aircraft and tower data obtained in the relatively simple terrain of the western Alaska tundra were used to determine the extent to which surface type variation can be related to fluxes of heat, moisture, and other properties. Surface type was classified as lake or land with aircraft borne infrared thermometer, and flight level heat and moisture fluxes were related to surface type. The magnitude and variety of sampling errors inherent in eddy correlation flux estimation place limits on how well any flux can be known even in simple geometries

An Spectrometer for Investigating the Spectral Momentum Density of Thin Films

An (e, 2e) spectrometer has been constructed for detecting scattered and recoiling electrons from a thin solid film. The cross section for observing the two electrons in coincidence is proportional to the spectral momentum density of the target. In this spectrometer the energy of the incident electron beam is 25 keV and the beam current is approximately 40 μA. The energy resolution (FWHM) is ≤4 eV. The momentum resolution (FWHM) can be varied from 0.2 to 1.0 Å−1. Preliminary coincidence data from an amorphous carbon film are presented

The Post-Common Envelope and Pre-Cataclysmic Binary PG 1224+309

We have made extensive spectroscopic and photometric observations of PG 1224+309, a close binary containing a DA white dwarf primary and an M4+ secondary. The H alpha line is in emission due to irradiation of the M-star by the hot white dwarf and is seen to vary around the orbit. From the radial velocities of the H alpha line we derive a period of P = 0.258689 +/- 0.000004 days and a semi-amplitude of K_Halpha = 160 +/- 8 km/s. We estimate a correction Delta_K = 21 +/- 2 km/s, where K_M = K_Halpha + Delta_K. Radial velocity variations of the white dwarf reveal a semi-amplitude of K_WD = 112 +/- 14 km/s. The blue spectrum of the white dwarf is well fit by a synthetic spectrum having T_eff = 29,300 K and log(g) = 7.38. The white dwarf contributes 97% of the light at 4500 Angstroms and virtually all of the light blueward of 3800 Angstroms. No eclipses are observed. The mass inferred for the white dwarf depends on the assumed mass of the thin residual hydrogen envelope: 0.40 < M_WD < 0.45 solar masses for hydrogen envelope masses of 0 < M_H < 4.0E-4 solar masses. We argue that the mass of the white dwarf is closer to 0.45 solar masses, hence it appears that the white dwarf has a relatively large residual hydrogen envelope. The mass of the M-star is then M_M = 0.28 +/- 0.05 solar masses, and the inclination is i = 77 +/- 7 degrees. We discuss briefly how PG 1224+309 may be used to constrain theories of close binary star evolution, and the past and future histories of PG 1224+309 itself. The star is both a ``post-common envelope'' star and a ``pre-cataclysmic binary'' star. Mass transfer by Roche-lobe overflow should commence in about 10 Gyr.Comment: 17 pages, 8 figures, AAS LaTeX, to appear in AJ, March 199

The stellar remnant of SN 1181

We report observations and modelling of the stellar remnant and presumed double-degenerate merger of Type~Iax supernova SN 1181 AD. It is the only known bound stellar SN remnant and the only star with Wolf-Rayet features that is neither a planetary nebula central star nor a massive Pop I progenitor. We model the unique emission-line spectrum with broad, strong O VI and O VIII lines as a fast stellar wind and shocked, hot gas. Non-LTE wind modeling indicates a mass-loss rate of $\sim 10^{-6}\,\rm M_\odot yr^{-1}$ and a terminal velocity of $\sim$15,000 km s$^{-1}$, consistent with earlier results. O VIII lines indicate shocked gas temperatures of $T \simeq 4$ MK. We derive a magnetic field upper limit of $B<2.5$ MG, below earlier suggestions. The luminosity indicates a remnant mass of $1.2\pm0.2$ $\rm M_\odot$ with ejecta mass $0.15\pm0.05$ $\rm M_\odot$. Archival photometry suggests the stellar remnant has dimmed by $\sim$0.5 magnitudes over 100 years. A low Ne/O $<0.15$ argues against a O-Ne white dwarf in the merger. A cold dust shell is only the second detection of dust in a SN Iax and the first of cold dust. Our ejecta mass and kinetic energy estimates of the remnant are consistent with Type Iax extragalactic sources.Comment: 19 pages, 13 figures, 3 tables. Submitte

Spectral Momentum Density from Graphite from Spectroscopy: Comparison with First Principles Calculations

We have measured the spectral momentum density ρ(E,q) of graphite by (e,2e) spectroscopy for momentum parallel and perpendicular to the crystal c axis. In the independent-electron approximation, ρ(E,q)=ΣG‖Uk(G)‖2 δ(q-k-G)δ(E-E(k)) where the one-electron wave function is Ψk(r)=eik⋅rΣGUk(G)eiG⋅r) and G is a reciprocal-lattice vector. The measurements covered a range of momentum parallel to the c axis equal to 0≤‖q‖≤1.84 Å-1 and a range of momentum perpendicular to the c axis equal to 0≤‖q‖≤2.35 Å-1. The energy range spanned the valence band of graphite from 4.4 eV above the Fermi energy to 27.6 eV below the Fermi energy. The momentum resolution was 0.47 and 0.73 Å-1 (full width at half maximum) for momentum parallel and perpendicular to the c axis, respectively. The energy resolution was 8.6 eV. The maximum coincidence rate was ∼0.02 counts/sec. The band structure E(k) and spectral density ‖Uk(G)‖2 have been calculated from first principles using a self-consistent density-functional theory in the local-density approximation with a mixed-basis pseudopotential technique. The agreement within experimental uncertainties between measurement and theory is excellent

Birth weight threshold for identifying piglets at-risk for preweaning mortality

Citation: Feldpausch, J. A., Jourquin, J., Bergstrom, J. R., Bokenkroger, C. D., Nelssen, J. L., Ritter, M. J., . . . Gonzalez, J. M. (2016). Birth weight threshold for identifying piglets at-risk for preweaning mortality. Journal of Animal Science, 94, 34-34. doi:10.2527/msasas2016-074The association of piglet birth weight (BtW) with early-life mortality risk is strongly supported by research of numerous studies reporting decreased preweaning piglet mortality as individual piglet BtW increases. The purpose of the present analysis was to identify a BtW threshold associated with reduced odds of preweaning survival. Observations from 2 studies with a total of 4068 piglets originating from 394 litters on 4 different commercial farms (3 European, 1 U.S.) were compiled for meta-analysis. Overall preweaning mortality rate across all farms was 12.2%. Data used in the analysis was weight of piglets within 24 h of birth and their corresponding survival outcome (dead or live) by weaning at 3 to 4 wk of age. A mixed effects logistic regression model was fit to estimate the probability of preweaning mortality based on BtW. A random effect of study was included to account for overall differences in mortality between the 2 studies. A piecewise linear predictor was selected to best represent the drastic decrease in preweaning mortality found as BtW increased in the range of 0.5 to 1.0 kg and the less extreme change in preweaning mortality observed for changes in weight above 1.0 kg. The model change point was determined by comparing model fit for BtW ranging from 0.5 kg to 2.0 kg based on maximizing the likelihood. A linear predictor equation was also generated to estimate the associated preweaning mortality probability associated with every 50 g of piglet BtW. Results indicated a 1.11 kg BtW change point in the log odds of piglet preweaning mortality, thus, implicating that every incremental change in BtW below 1.11 kg has a greater impact on mortality risk than incremental changes in BtW above 1.11 kg. Among the farms in this analysis, 14.9% of all piglets had BtW < 1.11 kg. These findings imply that interventions targeted at increasing the BtW of piglets having BtW less than 1.11 kg have tremendous potential to improve piglet preweaning survivability. A large percentage of the neonatal pig population falls below this weight threshold, and postnatal management strategies to decrease neonatal mortality should be directed toward these at-risk piglets

Evaluation of Esophageal Motility Utilizing the Functional Lumen Imaging Probe

© 2016 by the American College of Gastroenterology. Objectives:Esophagogastric junction (EGJ) distensibility and distension-mediated peristalsis can be assessed with the functional lumen imaging probe (FLIP) during a sedated upper endoscopy. We aimed to describe esophageal motility assessment using FLIP topography in patients presenting with dysphagia.Methods:In all, 145 patients (aged 18-85 years, 54% female) with dysphagia that completed up per endoscopy with a 16-cm FLIP assembly and high-resolution manometry (HRM) were included. HRM was analyzed according to the Chicago Classification of esophageal motility disorders; major esophageal motility disorders were considered "abnormal". FLIP studies were analyzed using a customized program to calculate the EGJ-distensibility index (DI) and generate FLIP topography plots to identify esophageal contractility patterns. FLIP topography was considered "abnormal" if EGJ-DI was < 2.8 mm 2 /mm Hg or contractility pattern demonstrated absent contractility or repetitive, retrograde contractions.Results:HRM was abnormal in 111 (77%) patients: 70 achalasia (19 type I, 39 type II, and 12 type III), 38 EGJ outflow obstruction, and three jackhammer esophagus. FLIP topography was abnormal in 106 (95%) of these patients, including all 70 achalasia patients. HRM was "normal" in 34 (23%) patients: five ineffective esophageal motility and 29 normal motility. In all, 17 (50%) had abnormal FLIP topography including 13 (37%) with abnormal EGJ-DI.Conclusions:FLIP topography provides a well-tolerated method for esophageal motility assessment (especially to identify achalasia) at the time of upper endoscopy. FLIP topography findings that are discordant with HRM may indicate otherwise undetected abnormalities of esophageal function, thus FLIP provides an alternative and complementary method to HRM for evaluation of non-obstructive dysphagia.Link_to_subscribed_fulltex