Operator's and organizational maintenance manual for radio set, AN/ARC-549, (FSN 5831-082-3598).

"July 1974."

Operator and organizational maintenance manual : radio set AN/ARC-102.

"27 November 1963."

Operator's and organizational maintenance manual : radio set AN/ARC-44.

"30 November 1960."

Operator's, organizational, and direct support maintenance manual for radio set AN/ARC-164(V)12 (NSN 5821-01-071-5624).

"30 July 1980."

Operator and organizational maintenance manual including repair parts and special tool lists : maintenance kit, electronic equipment, MK-1004/ARC.

"March 1968."

Operator and organizational maintenance manual : radio sets AN/ARC-73 and AN/ARC-73A.

"November 1962."

A short thesis on arc-welding

During the past few years the attention of architects, engineers and others encased in or connected with the building industry has been attracted to the possibilities of the application of welding processes to the joining of structural members. As oxy-acetylene welding was developed before electric arc welding became perfected it was only natural that the gas torch should be first considered. It developed however on examination of the two processes that while acetylene welding gave better results in most cases it was only in the hands of experts that it could consistently outscore the arc as a welding medium. Arc-welding has the advantage over the acetylene process, where each individual operator must use his own judgement as to the proper flame, in that a squad of arc-welders can work under the direction of a single expert supervisor who accepts the responsibility of fixing the current value and of determining the proper size of welding rod to be used on any given type of work.

Paranormal operator on a Hilbert space

In this thesis an extensive study is made of the set P of all paranormal operators in B(H), the set of all bounded endomorphisms on the complex Hilbert space H. T ϵ B(H) is paranormal if for each z contained in the resolvent set of T, d(z, σ(T))//(T-zI)^-1 = 1 where d(z, σ(T)) is the distance from z to σ(T), the spectrum of T. P contains the set N of normal operators and P contains the set of hyponormal operators. However, P is contained in L, the set of all T ϵ B(H) such that the convex hull of the spectrum of T is equal to the closure of the numerical range of T. Thus, N≤P≤L.

If the uniform operator (norm) topology is placed on B(H), then the relative topological properties of N, P, L can be discussed. In Section IV, it is shown that: 1) N P and L are arc-wise connected and closed, 2) N, P, and L are nowhere dense subsets of B(H) when dim H ≥ 2, 3) N = P when dimH ˂ ∞ , 4) N is a nowhere dense subset of P when dimH ˂ ∞ , 5) P is not a nowhere dense subset of L when dimH ˂ ∞ , and 6) it is not known if P is a nowhere dense subset of L when dimH ˂ ∞.

The spectral properties of paranormal operators are of current interest in the literature. Putnam [22, 23] has shown that certain points on the boundary of the spectrum of a paranormal operator are either normal eigenvalues or normal approximate eigenvalues. Stampfli [26] has shown that a hyponormal operator with countable spectrum is normal. However, in Theorem 3.3, it is shown that a paranormal operator T with countable spectrum can be written as the direct sum, N ⊕ A, of a normal operator N with σ(N) = σ(T) and of an operator A with σ(A) a subset of the derived set of σ(T). It is then shown that A need not be normal. If we restrict the countable spectrum of T ϵ P to lie on a C²-smooth rectifiable Jordan curve G_o, then T must be normal [see Theorem 3.5 and its Corollary]. If T is a scalar paranormal operator with countable spectrum, then in order to conclude that T is normal the condition of σ(T) ≤ G_o can be relaxed [see Theorem 3.6]. In Theorem 3.7 it is then shown that the above result is not true when T is not assumed to be scalar. It was then conjectured that if T ϵ P with σ(T) ≤ G_o, then T is normal. The proof of Theorem 3.5 relies heavily on the assumption that T has countable spectrum and cannot be generalized. However, the corollary to Theorem 3.9 states that if T ϵ P with σ(T) ≤ G_o, then T has a non-trivial lattice of invariant subspaces. After the completion of most of the work on this thesis, Stampfli [30, 31] published a proof that a paranormal operator T with σ(T) ≤ G_o is normal. His proof uses some rather deep results concerning numerical ranges whereas the proof of Theorem 3.5 uses relatively elementary methods.

Tolerance of Arc repressor to multiple-alanine substitutions

Arc repressor mutants containing from three to 15 multiple-alanine substitutions have spectral properties expected for native Arc proteins, form heterodimers with wild-type Arc, denature cooperatively with Tms equal to or greater than wild type, and, in some cases, fold as much as 30-fold faster and unfold as much as 50-fold slower than wild type. Two of the mutants, containing a total of 14 different substitutions, also footprint operator DNA in vitro. The stability of some of the proteins with multiple-alanine mutations is significantly greater than that predicted from the sum of the single substitutions, suggesting that a subset of the wild-type residues in Arc may interact in an unfavorable fashion. Overall, these results show that almost half of the residues in Arc can be replaced by alanine en masse without compromising the ability of this small, homodimeric protein to fold into a stable, native-like structure.

Contributions of distinct quaternary contacts to cooperative operator binding by Mnt repressor

Mnt, a tetrameric repressor encoded by bacteriophage P22, uses N-domain dimers to contact each half of its operator site. Experiments with a double mutant and structural homology with the P22 Arc repressor suggest that contacts made by Arg-28 and stabilized by Glu-33 are largely responsible for dimer–dimer cooperativity in Mnt. These dimer–dimer contacts are energetically more important for operator binding than solution tetramerization, which is mediated by an independent C-terminal coiled-coil domain. Indeed, once one dimer of the Mnt tetramer contacts an operator half site, binding of the second dimer occurs with an effective concentration much lower than that expected if both dimers were flexibly tethered. These results suggest that binding of the second dimer introduces some strain into the protein–DNA complex, a mechanism that could serve to limit the affinity of operator binding and to prevent strong binding of the Mnt tetramer to nonoperator sites.

Dual regulation of open-complex formation and promoter clearance by Arc explains a novel repressor to activator switch.

In studies of variants of the P(ant) promoter of bacteriophage P22, the Arc protein was found not only to slow the rate at which RNA polymerase forms open complexes but also to accelerate the rate at which the enzyme clears the promoter. These dual activities permit Arc, bound at a single operator subsite, to act as an activator or as a repressor of different promoter variants. For example, Arc activates a P(ant) variant for which promoter clearance is rate limiting in the presence and absence of Arc but represses a closely related variant for which open-complex formation becomes rate limiting in the presence of Arc. The acceleration of promoter clearance by Arc requires occupancy of the operator subsite proximal to the -35 region and is diminished when Arc bears a mutation in Arg-23, a residue that makes a DNA-backbone contact in the operator complex.