Interpretation of the prominence differential emissions measure for 3 geometries

Researchers have used prominence extreme ultraviolet line intensities observed from Skylab to derive the differential emission measure Q(T) in the prominence-corona (PC) interface from 3 x 10,000 to 3 times 1 million K, including the effects of Lyman Continuum absorption. Using lines both shortward and longward of the Lyman limit, researchers have estimated the importance of absorption as function of temperature. The magnitude of the absorption, as well as its rate of increase as a function of temperature, place limits on the thread scales and the character of the interfilar medium. Researchers have calculated models based on three assumed geometries: (1) threads with hot sheaths and cool cores; (2) isothermal threads; and (3) threads with longitudinal temperature gradients along the magnetic field. Comparison of the absorption computed from these models with the observed absorption in prominences shows that none of the geometries is totally satisfactory

Alumnae News

https://elischolar.library.yale.edu/ysn_alumninews/1060/thumbnail.jp

Development of a new high-rate anaerobic process for the treatment of industrial and domestic wastewaters: the anaerobic migrating blanket reactor (AMBR)

The anaerobic migrating blanket reactor (AMBR) was developed as a new high-rate system for the treatment of industrial and domestic wastewaters, at Iowa State University. The AMBR, a continuously fed, compartmentalized reactor, required mechanical mixing to obtain a sufficient biomass/substrate contact. The formation of granular biomass was not dependent on a hydraulic upflow pattern in the reactor, but was dependent on biomass migration over the horizontal plane of the reactor and the settling characteristics of the final compartment. To prevent acclimation of biomass in the final compartment, the flow was reversed in a horizontal matter. Keeping the pH sufficiently high in the initial compartment without recycling effluent was another advantage of reversing the flow. This also prevented total phase separation of acidogenesis and methanogenesis in the AMBR;Laboratory-scale AMBR systems have achieved high organic removal efficiencies when fed with non-acidified sucrose as a substrate at chemical oxygen demand (COD) loading rates up to 30 g/L/d. Furthermore, the AMBR was able to retain high levels of granular biomass at these loading rates. Due to moderate shear forces by mechanical mixing, the laboratory-scale AMBR was able to treat non-acidified sucrose at food to microorganism (FIM) ratios higher than found for other high rate systems. The AMBR out-competed the upflow anaerobic sludge blanket (UASB) and anaerobic sequencing batch reactor (ASBR) in a laboratory-scale comparison in terms of reactor performances and maximum organic loading rates;A mature granular blanket was formed after four months of operating a 54-liter AMBR, seeded with flocculent primary digester sludge. This was accomplished with moderate hydraulic selection pressures at the start of the run, in which reactor performances were sufficient to build up an active biomass, without losing the selection mechanism for better settling biomass;A 20-liter AMBR was able to effectively remove organic material from dilute non-fat dry milk (NFDM) solution at a concentration of 600 mg/L under psychrophilic conditions. Moreover, this reactor was able to retain its granular biomass after the hydraulic retention time (HRT) was decreased from four to one hour during hydraulic shock load studies. Finally, staging or partial phase separation was found in the AMBR in which relatively more methanogens were present in the inside compartments

Coronal and Prominence Plasmas

Various aspects of solar prominences and the solar corona are discussed. The formation of prominences, prominence diagnostics and structure, prominence dissappearance, large scale coronal structure, coronal diagnostics, small scale coronal structure, and non-equilibrium/coronal heating are among the topics covered

Measurement of the diffractive cross-section in deep inelastic scattering

Diffractive scattering of $\gamma^* p \to X + N$, where $N$ is either a proton or a nucleonic system with $M_N~<~4$~GeV has been measured in deep inelastic scattering (DIS) at HERA. The cross section was determined by a novel method as a function of the $\gamma^* p$ c.m. energy $W$ between 60 and 245~GeV and of the mass $M_X$ of the system $X$ up to 15~GeV at average $Q^2$ values of 14 and 31~GeV$^2$. The diffractive cross section $d\sigma^{diff} /dM_X$ is, within errors, found to rise linearly with $W$. Parameterizing the $W$ dependence by the form d\sigma^{diff}/dM_X \propto (W^2)^{(2\overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} -2)} the DIS data yield for the pomeron trajectory \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} = 1.23 \pm 0.02(stat) \pm 0.04 (syst) averaged over $t$ in the measured kinematic range assuming the longitudinal photon contribution to be zero. This value for the pomeron trajectory is substantially larger than \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} extracted from soft interactions. The value of \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} measured in this analysis suggests that a substantial part of the diffractive DIS cross section originates from processes which can be described by perturbative QCD. From the measured diffractive cross sections the diffractive structure function of the proton F^{D(3)}_2(\beta,Q^2, \mbox{x_{_{I\hspace{-0.2em}P}}}) has been determined, where $\beta$ is the momentum fraction of the struck quark in the pomeron. The form F^{D(3)}_2 = constant \cdot (1/ \mbox{x_{_{I\hspace{-0.2em}P}}})^a gives a good fit to the data in all $\beta$ and $Q^2$ intervals with $a = 1.46 \pm 0.04 (stat) \pmComment: 45 pages, including 16 figure