Heat transfer coefficients of non-Newtonian slurries in laminar flow

A total of 51 heat transfer runs were made in the first 25 runs, slurries of half micron and finer kaolin at 3.0, 5.6, 9.6 and 12.9% solids were used. Slurries of two microns and finer kaolin at 10.1, 13.7, 20.4 and 23.1% solids were used in the remaining 26 runs. The Reynolds Numbers ranged from 0.9 to 2,020 for the 51 runs. The data was correlated by the following equation: Hf/CbVbPb CbRb/Kb 2/3 = 0.70 DVbPb/Rb -2/3 for an L/D ratio of 68.7. This is essentially the accepted correlation for Newtonian fluids in laminar flow. The viscosity used for the slurries investigated was the apparent bulk viscosity obtained from measurements with a Fann V-G viscometer which gave shear rate versus viscosity data. The viscosity used was that at the same shear rate present in the heat exchanger

Interfacing Laboratory Instruments to Multiuser, Virtual Memory Computers

Computers based on virtual memory, multiuser architecture have recently become economically available to medium sized research groups (about 25 members). These new computers offer advantages to the experimentalist, though acceptance has been sometimes limited. One of the most important advantages of a virtual memory machine is the capability of fast access to arrays having dimensions greater than 64 kbytes. Arrays larger than 64 kbytes were available on some older computers based on physical memory. The access time to the memory beyond 64 kbytes is extremely slow for these systems. Fast access to large arrays is particularly important now where large data sets are required for research system

Irradiation-Mediated Rescue of T Cell–Specific V(D)j Recombination and Thymocyte Differentiation in Severe Combined Immunodeficient Mice by Bone Marrow Cells

In SCID (severe combined immunodeficient) mice, proper assembly of immunoglobulin and T cell receptor (TCR) genes is blocked by defective V(D)J recombination so that B and T lymphocyte differentiation is arrested at an early precursor stage. Treating the mice with gamma irradiation rescues V(D)J rearrangement at multiple TCR loci, promotes limited thymocyte differentiation, and induces thymic lymphomas. These effects are not observed in the B cell lineage. Current models postulate that irradiation affects intrathymic T cell precursors. Surprisingly, we found that transfer of irradiated SCID bone marrow cells to unirradiated host animals rescues both TCR rearrangements and thymocyte differentiation. These data indicate that irradiation affects precursor cells at an earlier stage of differentiation than was previously thought and suggest new models for the mechanism of irradiation rescue

Interstellar and Circumstellar Optical & Ultraviolet Lines Towards SN1998S

We have observed SN1998S which exploded in NGC3877, with the UES at the WHT and with the E230M echelle of STIS aboard HST. Both data sets were obtained at two seperate epochs. From our own Galaxy we detect interstellar absorption lines of CaII, FeII, MgI, and probably MnII from the edge of the HVC Complex M. We derive gas-phase abundances which are very similar to warm disk clouds in the local ISM, which we believe argues against the HVC material having an extragalactic origin. At the velocity of NGC3877 we detect interstellar MgI, MgII, MnII, CaII, & NaI. Surprisingly, one component is seen to increase by a factor of ~1 dex in N(NaI) and N(MgI) between the two epochs over which the data were taken. Unusually, our data also show narrow Balmer, HeI, and metastable FeII P-Cygni profiles, with a narrow absorption component superimposed on the bottom of the profile's absorption trough. Both the broad and narrow components of the optical lines are seen to increase substantially in strength between the two epochs. Most of the low-ionization absorption can be understood in terms of gas co-rotating with the disk of NGC 3877, providing the SN is at the back of an HI disk with a similar thickness to that of our own Galaxy. However, the variable absorption components, and the classic P-Cygni emission profiles, most likely arise in slow-moving circumstellar outflows originating from the red supergiant progenitor of SN1998S. [Abridged.]Comment: Accepted by ApJ, 26 pages including 9 figure

Target DNA Structure Plays a Critical Role in RAG Transposition

Antigen receptor gene rearrangements are initiated by the RAG1/2 protein complex, which recognizes specific DNA sequences termed RSS (recombination signal sequences). The RAG recombinase can also catalyze transposition: integration of a DNA segment bounded by RSS into an unrelated DNA target. For reasons that remain poorly understood, such events occur readily in vitro, but are rarely detected in vivo. Previous work showed that non-B DNA structures, particularly hairpins, stimulate transposition. Here we show that the sequence of the four nucleotides at a hairpin tip modulates transposition efficiency over a surprisingly wide (>100-fold) range. Some hairpin targets stimulate extraordinarily efficient transposition (up to 15%); one serves as a potent and specific transposition inhibitor, blocking capture of targets and destabilizing preformed target capture complexes. These findings suggest novel regulatory possibilities and may provide insight into the activities of other transposases

The Carnegie Supernova Project: Analysis of the First Sample of Low-Redshift Type-Ia Supernovae

We present the analysis of the first set of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project. Well-sampled, high-precision optical (ugriBV) and near-infrared (NIR; YJHKs) light curves obtained in a well-understood photometric system are used to provide light-curve parameters, and ugriBVYJH template light curves. The intrinsic colors at maximum light are calibrated to compute optical--NIR color excesses for the full sample, thus allowing the properties of the reddening law in the host galaxies to be studied. A low value of Rv~1.7, is derived when using the entire sample of SNe. However, when the two highly reddened SNe in the sample are excluded, a value Galactic standard of Rv~3.2 is obtained. The colors of these two events are well matched by a reddening model due to circumstellar dust. The peak luminosities are calibrated using a two-parameter linear fit to the decline rates and the colors, or alternatively, the color excesses. In both cases, dispersions in absolute magnitude of 0.12--0.16 mag are obtained, depending on the filter-color combination. In contrast to the results obtained from color excesses, these fits give Rv~1--2, even when the two highly reddened SNe are excluded. This discrepancy suggests that, beyond the "normal" interstellar reddening produced in the host galaxies, there is an intrinsic dispersion in the colors of SNe Ia which is correlated with luminosity but independent of the decline rate. Finally, a Hubble diagram is produced by combining the results of the fits for each filter. The resulting scatter of 0.12 mag appears to be limited by peculiar velocities as evidenced by the strong correlation between the distance-modulus residuals among the different filters. The implication is that the actual precision of SN Ia distances is 3--4%.Comment: 76 pages, 20 figures, accepted for publication in A

Personal experience of osteoarthritis and pain questionnaires: mapping items to themes

Purpose. The aim of this study was to examine the correspondence between qualitative and quantitative methods of coding experience of pain reported by participants with osteoarthritis (OA) of the knee. Method. A mapping grid was produced to record the correspondence between subthemes that emerged from thematic analysis of interviews with 24 participants with knee OA, and from questionnaire items which were used in a study of 192 knee OA participants. Items were rated according to their degree of correspondence between subthemes and questionnaire items and an overall correspondence score was produced for each subtheme and questionnaire measure. Results. The subthemes that corresponded well with the questionnaire items were those that related to socio-emotional functioning, the overall experience of pain and the impact of pain on physical functioning. The questionnaire items did not relate to participants' knowledge about their condition and their experience of the medical system. Conclusions. The study indicated that many aspects of pain experience reported by patients in qualitative interviews are also assessed by commonly used questionnaire outcome measures for people with pain. However, although participants reported that knowledge about their condition and their experience of the medical system were important aspects of the overall pain experience, these are rarely used as outcome measures. Questionnaires that address these additional aspects ofthe pain experience could be useful to further evaluate the experience of pain and may help to address importance concerns raised by patients with OA of the knee