239 research outputs found
Ghost Busting: PT-Symmetric Interpretation of the Lee Model
The Lee model was introduced in the 1950s as an elementary quantum field
theory in which mass, wave function, and charge renormalization could be
carried out exactly. In early studies of this model it was found that there is
a critical value of g^2, the square of the renormalized coupling constant,
above which g_0^2, the square of the unrenormalized coupling constant, is
negative. Thus, for g^2 larger than this critical value, the Hamiltonian of the
Lee model becomes non-Hermitian. It was also discovered that in this
non-Hermitian regime a new state appears whose norm is negative. This state is
called a ghost state. It has always been assumed that in this ghost regime the
Lee model is an unacceptable quantum theory because unitarity appears to be
violated. However, in this regime while the Hamiltonian is not Hermitian, it
does possess PT symmetry. It has recently been discovered that a non-Hermitian
Hamiltonian having PT symmetry may define a quantum theory that is unitary. The
proof of unitarity requires the construction of a new time-independent operator
called C. In terms of C one can define a new inner product with respect to
which the norms of the states in the Hilbert space are positive. Furthermore,
it has been shown that time evolution in such a theory is unitary. In this
paper the C operator for the Lee model in the ghost regime is constructed
exactly in the V/N-theta sector. It is then shown that the ghost state has a
positive norm and that the Lee model is an acceptable unitary quantum field
theory for all values of g^2.Comment: 20 pages, 9 figure
Identification of Important Factors Affecting Use of Digital Individualised Coaching and Treatment of Type 2 Diabetes in General Practice: A Qualitative Feasibility Study
Most type 2 diabetes patients are treated in general practice and there is a need of developing and implementing efficient lifestyle interventions. eHealth interventions have shown to be effective in promoting a healthy lifestyle. The purpose of this study was to test the feasibility, including the identification of factors of importance, when offering digital lifestyle coaching to type 2 diabetes patients in general practice. We conducted a qualitative feasibility study with focus group interviews in four general practices. We identified two overall themes and four subthemes: (1) the distribution of roles and lifestyle interventions in general practice (subthemes: external and internal distribution of roles) and (2) the pros and cons for digital lifestyle interventions in general practice (subthemes: access to real life data and change in daily routines). We conclude that for digital lifestyle coaching to be feasible in a general practice setting, it was of great importance that the general practitioners and practice nurses knew the role and content of the intervention. In general, there was a positive attitude in the general practice setting towards referring type 2 diabetes patients to digital lifestyle intervention if it was easy to refer the patients and if easily understandable and accessible feedback was implemented into the electronic health record. It was important that the digital lifestyle intervention was flexible and offered healthcare providers in general practice an opportunity to follow the type 2 diabetes patient closely
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An analysis of monthly home range size in the critically endangered California Condor Gymnogyps californianus
Condors and vultures comprise the only group of terrestrial vertebrates in the world that are
obligate scavengers, and these species move widely to locate ephemeral, unpredictable, and patchily-distributed
food resources. In this study, we used high-resolution GPS location data to quantify
monthly home range size of the critically endangered California Condor Gymnogyps californianus
throughout the annual cycle in California. We assessed whether individual-level characteristics
(age, sex and breeding status) and factors related to endangered species recovery program
efforts (rearing method, release site) were linked to variation in monthly home range size.
We found that monthly home range size varied across the annual cycle, with the largest monthly
home ranges observed during late summer and early fall (July-October), a pattern that may be
linked to seasonal changes in thermals that facilitate movement. Monthly home ranges of adults
were significantly larger than those of immatures, but males and females used monthly home
ranges of similar size throughout the year and breeding adults did not differ from non-breeding
adults in their average monthly home range size. Individuals from each of three release sites
differed significantly in the size of their monthly home ranges, and no differences in monthly
home range size were detected between condors reared under captive conditions relative to those
reared in the wild. Our study provides an important foundation for understanding the movement
ecology of the California Condor and it highlights the importance of seasonal variation in space
use for effective conservation planning for this critically endangered species
A Performant, Misuse-Resistant API for Primality Testing
Primality testing is a basic cryptographic task. But developers today are faced with complex APIs for primality testing, along with documentation that fails to clearly state the reliability of the tests being performed. This leads to the APIs being incorrectly used in practice, with potentially disastrous consequences. In an effort to overcome this, we present a primality test having a simplest-possible API: the test accepts a number to be tested and returns a Boolean indicating whether the input was composite or probably prime. For all inputs, the output is guaranteed to be correct with probability at least 1 - 2-128. The test is performant: on random, odd, 1024-bit inputs, it is faster than the default test used in OpenSSL by 17%. We investigate the impact of our new test on the cost of random prime generation, a key use case for primality testing. The OpenSSL developers have adopted our suggestions in full; our new API and primality test are scheduled for release in OpenSSL 3.0
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March 1955
Presidents Report - Frank P. Dunlap (page 1) The Student Purdue Serves - Dr. N. M. Parkhurst (2) A Student Reports - Bill Roach (4) Corrective Management of Shrubs - H. W. Gilbert (5) Nutrient Absorption by Plants - J. R. Watson Jr. (7) Disease Development is Slow - Dr. Wm. Klomparens (10) Poa Annua Control with Arsenic Materials - W. H. Daniel (11) Labor Relations - Cincinnati Country Club - John McCoy (14) Labor Policies at my Course - Ernest Schneider (15) Labor Policies at my Course - Don Strand (16) Nitrogen Use and Why - Robert M. Williams (17) Fertilizing Greens and Why - Don Likes(18) Nitrogen Use and Why - Lawrence Huber (20) Report on Experimental Green - Taylor Boyd (21) Experiences with Fairway Improvements - Ray Davis (23) Fairway Improvement Program - Bert Rost (24) Experiences on Merion Bluegrass - Carl Habenicht (24) Merion Bluegrass Experiences - P. E. Drachman (25) Zoysia for Lawns and Nurseries - P. E. Drachman (27) Preparation for Mortorized Carts - James W. Brandt (28) Preparing for Motorized Carts - Carl Bretzlaff (29) Merion Bluegrass Experiences - Ben O. Warren (31) Pennlu Distribution - W. H. Daniel(32) Zoysia for Midwest Lawns - W. H. Daniel (34) Crabgrass Prevention and Control - W. H. Daniel (36) Plant Carbohydrates Must Balance Nitrogen - M. R. Teel (39) Put Yourself in His Place - Fred Grau (40) Nitrogen Use and Why Wm. E. Lyons (45) The Management of Bentgrass Fairways - O. J. Noer (49) Fairway Improvement Program O. W. Young (52) Experiences with Zoysia - Ferank Dinelli (53
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