4,455 research outputs found
Recommended from our members
Di-μ-oxido-bis-[(1,4,8,11-tetra-aza-cyclo-tetra-decane-κN,N',N'',N''')dimangan-ese(III,IV)] bis-(tetra-phenyl-borate) chloride acetonitrile disolvate.
The title compound, [Mn(2)O(2)(C(10)H(24)N(4))(2)](C(24)H(20)B)(2)Cl·2CH(3)CN, is a mixed-valent Mn(III)/Mn(IV) oxide-bridged mangan-ese dimer with one chloride and two tetra-phenyl-borate counter-anions. There are two non-coordinated mol-ecules of acetonitrile in the formula unit. A center of inversion is present between the two metal atoms, and, consequently, there is no distinction between Mn(III) and Mn(IV) metal centers. In the Mn(2)O(2) core, the Mn-O distances are 1.817 (3) and 1.821 (3) Å. The cyclam ligand is in the cis configuration. The chloride counter-anion resides on a center of symmetry, whereas the tetra-phenyl-borate counter-anion is in a general position. The cyclam ligand is hydrogen bonded to the acetonitrile as well as to the chloride anion. One of the phenyl rings of the anion and the acetonitrile solvent molecule are each disordered over two sets of sites
School Phobia: A Review of Some Issues
It is now quite well established that children, usually said to be suffering from school phobia (Johnson et al, 1941). or school refusal (Morgan, 1959). have great difficulty in attending school as a result of a neurotic disturbance, and that this is quite distinct from truancy, which is more often part of an anti-social or conduct disorder (Warren, 1948; Hersov, 1960a). School phobia is a condition which involves more than a simple fear of school. Johnson et al (1941) claimed that the essential problem lay in an unresolved mutual dependency relationship between mother and child, with arousal of intense separation anxiety at the prospect of school attendance
Physical Attractiveness - a Source of Teacher Bias?
A person\u27s physical appearance is his personal characteristic most obvious and most accessible to others in social interaction. Despite some social psychologists apparent disinterest in investigating physical attractiveness as an antecedent of liking, there has been a developing body of research which suggests that physical attractiveness is an important social cue used by others as a basis for social evaluation. If, as there appears, there is a physical attractiveness stereotype, it seems plausible to suggest that a child\u27s personal characteristics may influence the way in which an adult evaluates his behaviour. There have been several studies that have looked at this issue as it might affect the classroom situation. These studies suggest that teachers may hold differential expectations for attractive and unattractive children
Value Systems of Prospective Teachers
The teacher in the primary school classroom provides for the children in her care a variety of experiences in number, in the language arts, and in all the other concomitants of the formal curriculum of the school. But she also provides other experiences: a set of socializing experiences arising from her behaviour in the classroom. This includes the types of interpersonal relationships she has with the children, the demands she makes, the expectations she has of individuals and groups and the priorities she sets. In this context an examination of factors lying behind the behaviours the teacher exhibits in the classroom is important. One factor seen as being of major relevance is the teacher\u27s value system
Perturbative Analysis of Spectral Singularities and Their Optical Realizations
We develop a perturbative method of computing spectral singularities of a
Schreodinger operator defined by a general complex potential that vanishes
outside a closed interval. These can be realized as zero-width resonances in
optical gain media and correspond to a lasing effect that occurs at the
threshold gain. Their time-reversed copies yield coherent perfect absorption of
light that is also known as an antilaser. We use our general results to
establish the exactness of the n-th order perturbation theory for an arbitrary
complex potential consisting of n delta-functions, obtain an exact expression
for the transfer matrix of these potentials, and examine spectral singularities
of complex barrier potentials of arbitrary shape. In the context of optical
spectral singularities, these correspond to inhomogeneous gain media.Comment: 13 pages, 2 figures, one table, a reference added, typos correcte
Creepy (not KREEPy) Gold-Indium Intermetallic Compounds on Secondary Ion Mass Spectrometry Samples
A series of Secondary Ion Mass Spectrometry (SIMS) sessions to measure hydrogen (H) in Martian meteorite minerals was completed using the Cameca 6f SIMS and NanoSIMS 50L at Arizona State University (ASU). During these sessions, a creeping phenomenon has occurred, where the edges of samples pressed in indium are covered by a metal alloy. We summarize these observations herein, present a collection of preliminary data, and discuss explanations and concerns for future SIMS work. We conclude the report with a research plan for further study
Bilateral symmetry breaking in a nonlinear Fabry-Perot cavity exhibiting optical tristability
We show the existence of a region in the parameter space that defines the
field dynamics in a Fabry-Perot cylindrical cavity, where three output stable
stationary states of the light are possible for a given localized incident
field. Two of these states do not preserve the bilateral (i.e. left-right)
symmetry of the entire system. These broken-symmetry states are the
high-transmission nonlinear modes of the system. We also discuss how to excite
these states.Comment: 5 pages, 5 figure
A multi-beam HI survey of the Virgo Cluster - two isolated HI clouds ?
We have carried out a fully sampled large area ()
21cm \HI line survey of part of the Virgo cluster using the Jodrell Bank
multi-beam instrument. The survey has a sensitivity some 3 times better than
the standard HIJASS and HIPASS surveys. We detect 31 galaxies, 27 of which are
well known cluster members. The four new detections have been confirmed in the
HIPASS data and by follow up Jodrell Bank pointed observations. One object lies
behind M86, but the other 3 have no obvious optical counter parts upon
inspection of the digital sky survey fields. These 3 objects were mapped at
Arecibo with a smaller \am{3}{6} HPBW and a 4 times better sensitivity than the
Jodrell Bank data, which allow an improved determination of the dimensions and
location of two of the objects, but surprisingly failed to detect the third.
The two objects are resolved by the Arecibo beam giving them a size far larger
than any optical images in the nearby field. To our mass limit of and column density limit of
atoms cm these new
detections represent only about 2% of the cluster atomic hydrogen mass. Our
observations indicate that the \HI mass function of the cluster turns down at
the low mass end making it very different to the field galaxy \HI mass
function. This is quite different to the Virgo cluster optical luminosity
function which is much steeper than that in the general field. Many of the
sample galaxies are relatively gas poor compared to \HI selected samples of
field galaxies, confirming the 'anaemic spirals' view of Virgo cluster late
type galaxies.Comment: Accepted for publication in MNRA
- …