7,642 research outputs found
The Fragile Balance of Power and Leadership
The aim of this article is to first define effective leadership and power, highlighting the differences between the two. The focal point is that power and effective leadership are not interchangeable and should not be treated as such. Power is a tool while effective leadership is a skill. Simply because a person wields power does not necessarily mean that he or she is an effective leader. Conversely, we will discuss how a leader is unquestionably endowed with a certain degree of power in order to maintain that particular position. Finally, because leaders have power at their disposal, we will explore ways in which power can negatively affect a leader, rendering that individual largely ineffective and exposing the extremely fragile relationship between these two terms
Characterization of the livestock production system and potential for enhancing productivity through improved feeding in Rangareddy district, India, September 2010
Characterization of the livestock production system and the potential of feed-based interventions for improving livestock productivity in Monomothpur and Khairpara village, in the Dinajpur district of northern Bangladesh
Characterization of the livestock production system and potential for enhancing productivity through improved feeding in Ol-Kalaou division, Kieni West district, Kenya, May 2010
Characterization of the livestock production system and the potential of feed-based interventions in the municipality of Ratnanagar and Gitanagar in the Chitwan district of southern Nepal, September 2010
Discovery of 21cm absorption in a DLA towards TXS 0311+430: The first low spin temperature absorber at z > 1
We report the detection of HI 21 cm absorption from the damped
Lyman- system (DLA) towards TXS 0311+430, with the Green Bank
Telescope. The 21 cm absorption has a velocity spread (between nulls) of km s and an integrated optical depth of km s. We also present new Giant Metrewave Radio
Telescope 602 MHz imaging of the radio continuum. TXS 0311+430 is unresolved at
this frequency, indicating that the covering factor of the DLA is likely to be
high. Combining the integrated optical depth with the DLA HI column density of
\nhi = \cm, yields a spin temperature of K, assuming a covering factor of unity. This is the first case of
a low spin temperature ( DLA and is among the lowest
ever measured in any DLA. Indeed, the measured for this DLA is similar to
values measured in the Milky Way and local disk galaxies. We also determine a
lower limit (Si/H) solar for the DLA metallicity, amongst the
highest abundances measured in DLAs at any redshift. Based on low redshift
correlations, the low , large 21 cm absorption width and high metallicity
all suggest that the DLA is likely to arise in a massive,
luminous disk galaxy.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS (Letters
Slice Stretching Effects for Maximal Slicing of a Schwarzschild Black Hole
Slice stretching effects such as slice sucking and slice wrapping arise when
foliating the extended Schwarzschild spacetime with maximal slices. For
arbitrary spatial coordinates these effects can be quantified in the context of
boundary conditions where the lapse arises as a linear combination of odd and
even lapse. Favorable boundary conditions are then derived which make the
overall slice stretching occur late in numerical simulations. Allowing the
lapse to become negative, this requirement leads to lapse functions which
approach at late times the odd lapse corresponding to the static Schwarzschild
metric. Demanding in addition that a numerically favorable lapse remains
non-negative, as result the average of odd and even lapse is obtained. At late
times the lapse with zero gradient at the puncture arising for the puncture
evolution is precisely of this form. Finally, analytic arguments are given on
how slice stretching effects can be avoided. Here the excision technique and
the working mechanism of the shift function are studied in detail.Comment: 16 pages, 4 figures, revised version including a study on how slice
stretching can be avoided by using excision and/or shift
High-Redshift Superclustering of QSO Absorption Line Systems on 100 Mpc Scales
We have analyzed the clustering of C IV absorption line systems in an
extensive new catalog of heavy element QSO absorbers. The catalog permits
exploration of clustering over a large range in both scale (from about 1 to
over 300 Mpc) and redshift (z from 1.2 to 4.5). We find significant evidence
(5.0 sigma) that C IV absorbers are clustered on comoving scales of 100 Mpc and
less --- similar to the size of voids and walls found in galaxy redshift
surveys of the local universe --- with a mean correlation function over these scales. We find, on these scales, that the mean
correlation function at low (z=1.7), medium (z=2.4), and high redshift (z=3.0)
is , , and , respectively.
Thus, the superclustering is present even at high redshift; furthermore, it
does not appear that the superclustering scale, in comoving coordinates, has
changed significantly since then. We find 7 QSOs with rich groups of absorbers
(potential superclusters) that account for a significant portion of the
clustering signal, with 2 at redshift . We find that the
superclustering is just as evident if we take instead of 0.5;
however, the inferred scale of clustering is then 240 Mpc , which is larger
than the largest scales of clustering known at present. This discrepancy may be
indicative of a larger value of , and hence . The evolution of
the correlation function on 50 Mpc scales is consistent with that expected in
cosmologies with density parameter ranging from 0.1 to 1.
Finally, we find no evidence for clustering on scales greater than 100 Mpc
() or 240 Mpc ().Comment: 16 LaTeX pages with 3 encapsulated Postscript figures included, uses
AASTeX (v. 4.0) available at ftp://ftp.aas.org/pubs/ , to appear in The
Astrophysical Journal Letter
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