10,152 research outputs found
Theta Graph Designs
We solve the design spectrum problem for all theta graphs with 10, 11, 12, 13, 14 and 15 edges
The Southern Vilnius Photometric System. IV. The E Regions Standard Stars
This paper is the fourth in a series on the extension of the Vilnius
photometric system to the southern hemisphere. Observations were made of 60
stars in the Harvard Standard E regions to increase a set of standard stars.Comment: 6 pages, TeX, requires 2 macros (baltic2.tex, baltic4.tex) included
no figures, to be published in Baltic Astronomy, Vol 6, pp1-6 (1997
Strategy and tactics in mediaeval Scotland
Offensive operations by the Scots in the Middle Ages
were confined to the single sphere of the north of England and
can be divided into two chronological periods. In the twelfth
century the object of the invasions was the conquest and retentio7
of the northern counties; in the thirteenth, fourteenth, fifteenth
and sixteenth, the aim was simply to cause diversions of the
strength of England from more vital points at home or abroad.Permanent conquest necessitated the existence of elaborate siege equipment and a disciplined army of occupation at a time when Scotland possessed neither the one nor the other. In
occupying a district which is meant to be held indefinitely, care
must be taken to secure possession of the fortresses, the fetters
of the country, and to conciliate the inhabitants by respecting
their lives and property. The armies of David I and of William the
Lion could not do these things. Their attempts at sieges were gene
rally unsuccessful, and the composition of their bands rendered
sporadic plundering inevitable. The leaders were not responsible
for this state of affairs; the state of civilisation in Scotland
e was not yet far enough advanced to allow of the formation of a wei
disciplined host,or, which was more important, of a properly organised system of supply which would have rendered wasteful foraging
unnecessary. It may be, however, that the attacks, failures as
they were, served the purpose of a true defensive at a time when
the lack of unification in Scotland would have made the country a
prey to an organised English conquest.The mistaken nature of the policy of running risks on
behalf of France has already been commented on. The true military
sphere of raids of diversion in the north of England was to draw
away the southern forces from an attack on a northern fortress or
district or to bring pressure to bear on the southern government
and thus secure a favourable peace. Thus the attacks made by
Bruce and his lieutenants were truly defined in their scope and
resulted in the saving of Berwick and in the extraction of the
peace of Northampton from an exhausted enemy. The successful
handling of these raids required a high degree of perseverance at
a time when things might be going badly elsewhere. When thef qualm
ty was lacking disaster followed, as in the battles of Dunbar and
Ialidon Hill. On the other hand, even when Walter was hard pressed
in Berwick, Bruce steadfastly refused to risk a battle for the
town. Pitched battles, as distinct from combats, had to be
avoided in these expeditions. Neville's Cross and Flodden were
avoidable disasters brought about by violation of this rule.
Otterburn was a successful battle, but it brought to the Scots
only a gain in prestige. The most disastrous campaign which the
English fought in their own country, that of Weardale, did not
contain a single open action.In this work, where detailed attention can only be
directed to the more outstanding actions, the cumulative effect
of raids has not been stressed. No account can be taken of the
scores of minor parties which crossed the English border at
various periods, but the mass result cf these operations was very
great. This system of warfare gradually created a line of defence
which was difficult to pass, but it also brought about in a later
stage of the country's development as state of anarchy which was
with difficulty corrected by the later rulers.In the Middle Ages military power was mostly in the
hands of the barons who constituted, as it were, the military
aristocracy. This was an inevitable sequel to the feudal system
of landholding, which made the tenants-in-chief the king's
lieutenants in the national levy. While all men of rank were
soldiers, there were practically no professional leaders of armies.
From his very nature the soldier of fortune was an
adventurer or mandless man. As an adviser or as the leader of a
contingent of mercenaries he was welcome, but it was very rarely
that he rose to the command of an army. In most cases the barons
would not have tolerated such promotion over their heads, though
there. is little doubt that such men as Walter Manny had as much
military intelligence as most of the barons put together. Occasionally a country, especially England, produced a king who could
bring to his natural position of leadership great military
intelligence. Generally, however, the multiplicity of the king's
duties prevented his becoming proficient as a general and he was
dependent upon the advice of a council of barons with no more
ability in the matter than himself; this was almost constantly
true in the case of France.As a general rule the barons made good fighters, but
most indifferent leaders. When the list of English successes
gained at the expense of the Scots is examined, it is found that at Dunbar, Falkirk, and Halidon Hill the king led the army and
that in the latter two cases he directed its movements in person.
At the Standard and at Neville's Cross the northern barons of
England did not show any outstanding skill; rather it was the
Scottish leaders who showed ineptitude. At Flodden Surrey did not
show himself in any way a distinguished master of war. Edward II
was the only English king defeated in plain battle by the Scots,
and it is out the question to say that he controlled the English
army at Bannockburn. In brief the tide of English success rose
highest during the reigns of her two general- kings, Edward I and
Edward III, and that of Scottish victory during the period of
Bruce. The Scottish barons had the melancholy privilege of
possessing a long list of such incompetent generals as Archibald
Douglas and Donald, Earl of March cannot be plausibly alleged
that the failure of the baronial leaders was due to the fact that
the successful principles of Scottish war had not been adequately
demonstrated. They appeared clearly under Wallace in a defensive
sense and developed under Bruce in an offensive direction. Yet
after the peace of Northampton there appeared a most unfortunate
neglect of the lessons learned at so great a cost, and repeatedly
the most elementary rules of Scottish warfare were violated in
glaring fashion. It is not easy to find an explanation of this
negligent behaviour. English leaders did apply the teaching of
Dupplin Moor to some practical purpose, and even the French
tried to avoid in later actions the primary error of the Crecy
catastrophe. But the Scottish barons, in a fashion almost
systematic, forgot the old tricks and failed to produce any new ones. Even in an inbred aristocracy depending on brawn rather than
on brains, something better than this was to be expected. Perhaps
it was due to the fact that most of the barons were absent from
Scotland at the period of the war of Independence. The more
probable explanation is, however, that no pains were taken to pass
on the fruits of acquired experience from one generation to another. Scotland in the Middle Ages could not foster a Staff College,
but it might have possessed a few elementary rules and regulations
in written form. Yet the fact remains that, apart from Bruce's
testament, there exists nothing approaching a text book on the
principles of Scottish warfare.The redeeming feature is the prolific crop of
partisan leaders which Scotland invariably produced from the ranks
of the knights and of the common people in times of danger. This
is a tribute to the undoubted military ability of the commons,
which has appeared even more markedly in modern times. It was also
the primary explanation of% the fact that Scotland was able to
maintain her independence, a performance which, despite the
defeats suffered in the process will remain on record as a wonderful effort in the face of natural disadvantages, misdirected
leadership, and an exceptionally formidable enemy. Our summing up
must be in favour of the people and adverse to their leaders as a
whole
The optical and near-infrared properties of nearby groups of galaxies
We present a study of the optical (BRI) and near-infrared (JHK) luminosity
fuctions (LFs) of the GEMS sample of 60 nearby groups of galaxies between
0<z<0.04, with our optical CCD photometry and near-IR photometry from the 2MASS
survey. The LFs in all filters show a depletion of galaxies of intermediate
luminosity, two magnitudes fainter than L*, within 0.3 R{500} from the centres
of X-ray faint groups. This feature is not as pronounced in X-ray bright
gropus, and vanishes when LFs are found out to R{500}, even in the X-ray dim
groups. We argue that this feature arises due to the enhanced merging of
intermediate-mass galaxies in the dynamically sluggish environment of low
velocity-dispersion groups, indicating that merging is important in galaxy
evolution even at z~0.Comment: to appear in the proceedings of the ESO workshop "Groups of Galaxies
in the Nearby Universe", Santiago, Dec 5-9, 2005. Eds. I. Saviane, V. Ivanov,
& J. Borissova (Springer Verlag); 5 page
Characterization of high-dimensional entangled systems via mutually unbiased measurements
Mutually unbiased bases (MUBs) play a key role in many protocols in quantum
science, such as quantum key distribution. However, defining MUBs for arbitrary
high-dimensional systems is theoretically difficult, and measurements in such
bases can be hard to implement. We show experimentally that efficient quantum
state reconstruction of a high-dimensional multi-partite quantum system can be
performed by considering only the MUBs of the individual parts. The state
spaces of the individual subsystems are always smaller than the state space of
the composite system. Thus, the benefit of this method is that MUBs need to be
defined for the small Hilbert spaces of the subsystems rather than for the
large space of the overall system. This becomes especially relevant where the
definition or measurement of MUBs for the overall system is challenging. We
illustrate this approach by implementing measurements for a high-dimensional
system consisting of two photons entangled in the orbital angular momentum
(OAM) degree of freedom, and we reconstruct the state of this system for
dimensions of the individual photons from d=2 to 5.Comment: 8 page
Diamonds on the Hat: Globular Clusters in The Sombrero Galaxy (M104)
Images from the HST ACS are used to carry out a new photometric study of the
globular clusters (GCs) in M104, the Sombrero galaxy. The primary focus of our
study is the characteristic distribution function of linear sizes (SDF) of the
GCs. We measure the effective radii for 652 clusters with PSF-convolved King
and Wilson dynamical model fits. The SDF is remarkably similar to those
measured for other large galaxies of all types, adding strong support to the
view that it is a "universal" feature of globular cluster systems.
We develop a more general interpretation of the size distribution function
for globular clusters, proposing that the shape of the SDF that we see today
for GCs is strongly influenced by the early rapid mass loss during their star
forming stage, coupled with stochastic differences from cluster to cluster in
the star formation efficiency (SFE) and their initial sizes. We find that the
observed SDF shape can be accurately predicted by a simple model in which the
protocluster clouds had characteristic sizes of pc and SFEs of
. The colors and luminosities of the M104 clusters show the
clearly defined classic bimodal form. The blue sequence exhibits a
mass/metallicity relation (MMR), following a scaling of heavy-element abundance
with luminosity of very similar to what has been found in most
giant elliptical galaxies. A quantitative self-enrichment model provides a good
first-order match to the data for the same initial SFE and protocluster size
that were required to explain the SDF. We also discuss various forms of the
globular cluster Fundamental Plane (FP) of structural parameters, and show that
useful tests of it can be extended to galaxies beyond the Local Group.Comment: In press for MNRA
USING CROWDFUNDING AS PART OF THE PRODUCT DEVELOPMENT PROCESS
AbstractCrowdfunding is the process of taking a project in need of investment and asking a large group of people to supply the investment. It allows organisations to sell their product before production, reducing the risk of new product development. Organisations such as Tesla and General Electric have used crowdfunding successfully but crowdfunding is yet to be explored as part of a formalised product development framework. This paper includes the business case for commercialising new products with crowdfunding and presents crowdfunding as part of a product development and commercialisation framework.</jats:p
- …