10,962 research outputs found
(η5‐Cyclopentadienyl)Tricarbonylmanganese(I) Complexes
Since the initial preparation of (η5‐C5H5)Mn(CO)3 by Fischer and Jira in 1954, many methods have been developed for the synthesis of this compound (often referred to as “cymantrene”) and its C5 substituted derivatives. Interestingly, each of these preparations has at least one significant drawback from a preparative perspective (thallium reagents, high pressures, poor yields, or reactants that require significant preparative investment). Surprisingly missing from this collection of preparative methods is the direct reaction between commercially available Mn(CO)5Br and NaC5H5. In 1988, however, Smart and coworkers found MnBr(CO)3(pyridine)2 to be an effective reagent in making a substituted indacenylmanganese tricarbonyl complex. As this pyridine complex also serves as an effective manganese starting material, this chapter discusses the high‐yield syntheses of cymantrene and its derivatives such as (η5‐C5Me5)Mn(CO)3
Melodic expectations in 5- to 6-year-old children
It has been argued that children implicitly acquire the rules relating to the structure of music in their environment, using domain-general mechanisms such as statistical learning. Closely linked to statistical learning is the ability to form expectations about future events. Whether children as young as 5 years can make use of such internalized regularities to form expectations about the next note in a melody is still unclear. The possible effect of the home musical environment on the strength of musical expectations has also been under-explored. Using a newly developed melodic priming task that included melodies with either “expected” or “unexpected” endings according to rules of Western music theory, we tested 5-and 6-year old children (N = 46). The stimuli in this task were constructed using the Information Dynamics Of Music or IDyOM system, a probabilistic model estimating the level of “unexpectedness” of a note given the preceding context. Results showed that responses to expected versus unexpected tones were faster and more accurate indicating that children have already formed robust melodic expectations at the age of 5. Aspects of the home musical environment significantly predicted the strength of melodic expectations suggesting that implicit musical learning may be influenced by the quantity of informal exposure to the surrounding musical environment
Incoherent Transport through Molecules on Silicon in the vicinity of a Dangling Bond
We theoretically study the effect of a localized unpaired dangling bond (DB)
on occupied molecular orbital conduction through a styrene molecule bonded to a
n++ H:Si(001)-(2x1) surface. For molecules relatively far from the DB, we find
good agreement with the reported experiment using a model that accounts for the
electrostatic contribution of the DB, provided we include some dephasing due to
low lying phonon modes. However, for molecules within 10 angstrom to the DB, we
have to include electronic contribution as well along with higher dephasing to
explain the transport features.Comment: 9 pages, 5 figure
Dietary fat and carbohydrates differentially alter insulin sensitivity during caloric restriction
BACKGROUND AND AIMS: We determined the effects of acute and chronic calorie restriction with either a low-fat, high-carbohydrate diet or a low-carbohydrate diet on hepatic and skeletal muscle insulin sensitivity. METHODS: Twenty-two obese subjects (body-mass index, 36.5±0.8kg/m(2)) were randomized to a high-carbohydrate (>180g/d) or low-carbohydrate (<60g/d) energy-deficit diet. A euglycemic–hyperinsulinemic clamp, muscle biopsies, and magnetic resonance spectroscopy were used to determine insulin action, cellular insulin signaling and intrahepatic triglyceride content before, after 48 h, and after ~11 wks (7% weight loss) of diet therapy. RESULTS: At 48 h, intrahepatic triglyceride content decreased more in the low-carbohydrate than the high-carbohydrate diet group (29.6±4.8% vs. 8.9±1.4%; P<0.05), but was similar in both groups after 7% weight loss (low-carbohydrate diet, 38.0±4.5% vs. high-carbohydrate diet, 44.5±13.5%). Basal glucose production rate decreased more in the low-carbohydrate than the high-carbohydrate diet group at 48 h (23.4±2.2% vs. 7.2±1.4%, P<0.05) and after 7% weight loss (20.0±2.4% vs. 7.9±1.2%, P<0.05). Insulin-mediated glucose uptake did not change at 48 h, but increased similarly in both groups after 7% weight loss (48.4±14.3%, P<0.05). In both groups, insulin-stimulated phosphorylation of Jun N-terminal kinase decreased by 29±13% and phosphorylation of Akt and insulin receptor substrate -1 increased by 35±9% and 36±9%, respectively, after 7% weight loss (all p<0.05). CONCLUSION: Moderate calorie restriction causes temporal changes in liver and skeletal muscle metabolism; 48 h of calorie restriction affects the liver (intrahepatic triglyceride content, hepatic insulin sensitivity, and glucose production), whereas moderate weight loss affects muscle (insulin-mediated glucose uptake and insulin signaling)
A Herschel study of the properties of starless cores in the Polaris Flare dark cloud region using PACS and SPIRE
The Polaris Flare cloud region contains a great deal of extended emission. It
is at high declination and high Galactic latitude. It was previously seen
strongly in IRAS Cirrus emission at 100 microns. We have detected it with both
PACS and SPIRE on Herschel. We see filamentary and low-level structure. We
identify the five densest cores within this structure. We present the results
of a temperature, mass and density analysis of these cores. We compare their
observed masses to their virial masses, and see that in all cases the observed
masses lie close to the lower end of the range of estimated virial masses.
Therefore, we cannot say whether they are gravitationally bound prestellar
cores. Nevertheless, these are the best candidates to be potentialprestellar
cores in the Polaris cloud region.Comment: 5 pages, 2 figures, accepted by A&
On the classification and bifurcation of multigerms of maps from surfaces to 3-space
The A-classification of multigerm singularities is discussed, based on the
theory of complete transversals. An A-classification of r-multigerms from theplane to 3-space of A-codimension = 6 - r is carried out and the bifurcation geometry of these singularities analysed. This work has applications to the study of two-dimensional spatial motions, giving local models for the singularities which appear on general trajectories of rigid body motions from theplane to 3-space. In addition, our classification is extensive enough to give the full list of simple multigerm singularities from the plane to 3-space
Classification and stability of simple homoclinic cycles in R^5
The paper presents a complete study of simple homoclinic cycles in R^5. We
find all symmetry groups Gamma such that a Gamma-equivariant dynamical system
in R^5 can possess a simple homoclinic cycle. We introduce a classification of
simple homoclinic cycles in R^n based on the action of the system symmetry
group. For systems in R^5, we list all classes of simple homoclinic cycles. For
each class, we derive necessary and sufficient conditions for asymptotic
stability and fragmentary asymptotic stability in terms of eigenvalues of
linearisation near the steady state involved in the cycle. For any action of
the groups Gamma which can give rise to a simple homoclinic cycle, we list
classes to which the respective homoclinic cycles belong, thus determining
conditions for asymptotic stability of these cycles.Comment: 34 pp., 4 tables, 30 references. Submitted to Nonlinearit
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