We present single-epoch spectropolarimetry of the Type II supernovae (SNe II) 1997ds, 1998A, and 1999gi. SN 1997ds and SN 1998A were both observed during the early photospheric phase, less than 50 days after explosion, while spectropolarimetry of SN 1999gi was obtained near the start of the transition to the nebular phase, about 110 days after explosion. Uncorrected for interstellar polarizatio...

In this paper we highlight some enumerative results concerning matroids of low rank and prove the tail-ends of various sequences involving the number of matroids on a finite set to be log-convex. We give a recursion for a new, slightly improved, lower bound on the number of rank-r matroids on n elements when n = 2 − 1. We also prove an adjacent result showing the point-lines-planes conjecture t...

The Cu-Sn metallurgical soldering reaction in two-segmented Cu-Sn nanowires is studied by in situ transmission electron microscopy. By varying the relative lengths of Cu and Sn segments, we show that the metallurgical reaction results in a Cu-Sn solid solution for small Sn/Cu length ratio while Cu-Sn intermetallic compounds (IMCs) for larger Sn/Cu length ratios. Upon heating the nanowires to ∼5...

The title distannoxane, [Sn(4)(CH(3))(8)(C(3)H(4)N(3)S)(2)(CH(3)O)(2)O(2)], lies about a center of inversion; the tetra-nuclear mol-ecule features a three-rung-staircase Sn(4)O(4) core in which the two crystallographically independent Sn(IV) atoms are bridged by the triazolide group. The negatively charged N atom of the triazolide group binds to the terminal Sn atom at a shorter distance [Sn-N ...

An Sn,k refers to a generalized version of an n-star graph (Sn), where Sn,n−1 and Sn are isomorphic and Sn,1 is obviously a complete graph of n vertices (Kn). This study constructs a set of many-to-one vertex-disjoint paths in an (n, k)-star graph (Sn,k), and computes the upper bound of Rabin number of an Sn,k, where 2≤k≤n−1. The upper bound of the Rabin number of an Sn,k is calculated by const...

The tetra-nuclear title compound, [Sn4(CH3)8(C2H5O)2O2(C3H4N3S)2], lies about a center of inversion; the mol-ecule features a three-rung-staircase Sn4O4 core in which two Sn(IV) atoms are bridged by the 4-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-ide group. The negatively charged N atom of the group binds to the terminal Sn(IV) atom at a shorter distance [Sn-N = 2.240 (3) Å] compar...

We set sensitive upper limits to the X-ray emission of four Type Ia supernovae (SNe Ia) using the Chandra X-ray Observatory. SN 2002bo, a normal, although reddened, nearby SN Ia, was observed 9.3 days after explosion. For an absorbed, high temperature bremsstrahlung model the flux limits are 3.2 × 10 ergs cm s (0.5–2 keV band) and 4.1 × 10 ergs cm s (2–10 keV band). Using conservative model ass...

BACKGROUND The potential morbidity of an axillary lymph node dissection in patients with breast cancer can be avoided in patients with a negative sentinel node (SN). HYPOTHESIS It may be possible to identify a subset of patients with a positive SN and without metastases in the remaining axillary lymph nodes. DESIGN Case-control study. SETTING Both primary and referral hospital care. PAT...

We have employed ab initio molecular dynamics to investigate the equilibrium geometries, energetics, and the nature of bonding in mixed Li-Sn clusters. Our studies reveal that a small percentage of Sn in Li-rich clusters introduces significant changes in the equilibrium geometries. It is also seen that the geometries of Sn-rich clusters are influenced by the Sn10 motif. Analysis of the nature o...