4,112 research outputs found
On the embeddability of certain infinitely divisible probability measures on Lie groups
We describe certain sufficient conditions for an infinitely divisible
probability measure on a class of connected Lie groups to be embeddable in a
continuous one-parameter convolution semigroup of probability measures.
(Theorem 1.3). This enables us in particular to conclude the embeddability of
all infinitely divisible probability measures on certain Lie groups, including
the so called Walnut group (Corollary 1.5). The embeddability is concluded also
under certain other conditions (Corollary 1.4 and Theorem 1.6).Comment: 24 page
Symmetry and optical selection rules in graphene quantum dots
Graphene quantum dots (GQD's) have optical properties which are very
different from those of an extended graphene sheet. In this Article we explore
how the size, shape and edge--structure of a GQD affect its optical
conductivity. Using representation theory, we derive optical selection rules
for regular-shaped dots, starting from the symmetry properties of the current
operator. We find that, where the x- and y-components of the current operator
transform with the same irreducible representation (irrep) of the point group -
for example in triangular or hexagonal GQD's - the optical conductivity is
independent of the polarisation of the light. On the other hand, where these
components transform with different irreps - for example in rectangular GQD's -
the optical conductivity depends on the polarisation of light. We find that
GQD's with non-commuting point-group operations - for example dots of
rectangular shape - can be distinguished from GQD's with commuting point-group
operations - for example dots of triangular or hexagonal shape - by using
polarized light. We carry out explicit calculations of the optical conductivity
of GQD's described by a simple tight--binding model and, for dots of
intermediate size, \textcolor{blue}{()}
find an absorption peak in the low--frequency range of the spectrum which
allows us to distinguish between dots with zigzag and armchair edges. We also
clarify the one-dimensional nature of states at the van Hove singularity in
graphene, providing a possible explanation for very high exciton-binding
energies. Finally we discuss the role of atomic vacancies and shape asymmetry.Comment: 24 pages, 15 figure
Ethnographic Moment: Navajo Nation Changing Racial Terminology in Response to Black Lives Matter Protests
Given Navajo Nation debates about changing racial terminology in response to Black Lives Matter protests, I will argue that modification of Diné Bizaad (Diné Bizaad means Navajo Language) is a progressive and positive shift. Language is constantly changing across social groups and time. From generation to generation, words take on different meanings. Words are invented and acquired from a variety of sources. Furthermore, unused words can expire from everyday usage. How do shifts in language occur
A Grief Intervention for Early Perinatal Loss
Early pregnancy loss has a multidimensional effect on patients, touching the body, soul, and spirit. This project addresses patientsâ lack of spiritual and emotional support following early pregnancy loss, commonly called a miscarriage. The available research on the emotional impact of early pregnancy loss has grown stronger over the last three decades. However, there is a deficit of research exploring the spiritual implications of miscarriage and how faith is used as a coping mechanism for pregnancy grief. In modern culture, the term spirituality can mean many different things. With this awareness, Mercy Healthcare embraces and supports patients wherever they find themselves spiritually. As a faith-based institution, Mercy acknowledges the importance of spirituality and personal faith in the healing process. When supporting early pregnancy loss at Mercy Springfield, the Pastoral Services department has a definitive standard of care. Nevertheless, a lack of vital ongoing support is unavailable for patients who desire additional assistance in their grief. This study creates an intervention to support the grief of early pregnancy loss patients through an eight-week phenomenological review considering individual life and faith stories. This project, led by a professionally trained chaplain, applied both qualifiable and quantifiable research techniques using patient and stakeholder surveys and the project leaderâs observational data. It investigates whether further understanding oneâs life stories and faith experiences can promote quality patient care in their grieving process. The project will also provide additional resources to promote awareness and support of the spiritual aspects of miscarriage grief. In addition, this study will serve as a guide to further evaluate quality patient care offered by Pastoral Services at Mercy Springfield
Cancer
This poster for the Natural Sciences Poster Session at Parkland College features the constellation Cancer, its ten brightest stars and Messier objects. Cancer (the crab) is a zodiac constellations located between Leo and Gemini. The student identified the ten different key stars and graphed their altitudes and azimuth to calculate their lifespans. He also described the two Messier objects and calculated how many days are in a year according to the rise times of a star in the constellation
Cancer
This poster for the Natural Sciences Poster Session at Parkland College features the constellation Cancer, its ten brightest stars and Messier objects. Cancer (the crab) is a zodiac constellations located between Leo and Gemini. The student identified the ten different key stars and graphed their altitudes and azimuth to calculate their lifespans. He also described the two Messier objects and calculated how many days are in a year according to the rise times of a star in the constellation
Strong Electronic Correlation Effects in Coherent Multidimensional Nonlinear Optical Spectroscopy
We discuss a manyâbody theory of the coherent ultrafast nonlinear optical response of systems with a strongly correlated electronic ground state that responds unadiabatically to photoexcitation. We introduce a truncation of quantum kinetic density matrix equations of motion that does not rely on an expansion in terms of the interactions and thus applies to strongly correlated systems. For this we expand in terms of the optical field, separate out contributions to the timeâevolved manyâbody state due to correlated and uncorrelated multiple optical transitions, and use âHubbard operatorâ density matrices to describe the exact dynamics of the individual contributions within a subspace of strongly coupled states, including âpure dephasingâ. Our purpose is to develop a quantum mechanical tool capable of exploring how, by coherently photoexciting selected modes, one can trigger nonlinear dynamics of strongly coupled degrees of freedom. Such dynamics could lead to photoinduced phase transitions. We apply our theory to the nonlinear response of a twoâdimensional electron gas (2DEG) in a magnetic field. We coherently photoexcite the two lowest Landau level (LL) excitations using three timeâdelayed optical pulses. We identify some striking temporal and spectral features due to dynamical coupling of the two LLs facilitated by interâLandauâlevel magnetoplasmon and magnetoroton excitations and compare to threeâpulse fourâwaveâmixing (FWM) experiments. We show that these features depend sensitively on the dynamics of fourâparticle correlations between an electronâhole pair and a magnetoplasmon/magnetoroton, reminiscent of excitonâexciton correlations in undoped semiconductors. Our results shed light into unexplored coherent dynamics and relaxation of the quantum Hall system (QHS) and can provide new insight into nonâequilibrium coâoperative phenomena in strongly correlated systems
When evaluating a presidentâs economic performance, voters look across their entire record â not just the recent short term.
How do voters decide? Do they take everything into account that happened over the governmentâs time in office? Or do they rely only on the recent past? Timothy Hellwig and Dani M. Marinova report that voters, counter to conventional understandings, are not so short-sighted. Their analysis of vote intentions in the run up to the 2012 presidential election reveals that voters are no more accurate in assessing economic performance over the short term compared to the long term. Voters, it turns out, are more misinformed than short-sighted
Ultrafast Enhancement of Ferromagnetism via Photoexcited Holes in GaMnAs
We report on the observation of ultrafast photo-enhanced ferromagnetism in
GaMnAs. It is manifested as a transient magnetization increase on a 100-ps time
scale, after an initial sub-ps demagnetization. The dynamic magnetization
enhancement exhibits a maximum below the Curie temperature Tc and dominates the
demagnetization component when approaching Tc. We attribute the observed
ultrafast collective ordering to the p-d exchange interaction between
photoexcited holes and Mn spins, leading to a correlation-induced peak around
20K and a transient increase in Tc.Comment: 4 page
Pemetaan Kerawanan Banjir dengan Aplikasi Sistem Informasi Geografis di Sub DAS Karang Mumus Provinsi Kalimantan Timur
Sub DAS Karang Mumus merupakan bagian dari sistem DAS Mahakam yang lebih besar, memiliki luas ±30.000 ha dianggap memiliki kontribusi dalam menentukan kerawanan banjir yang sering terjadi di Kota Samarinda dan sekitarnya. Tujuan penelitian ini adalah memetakan daerah yang termasuk dalam daerah rawan kebanjiran dan daerah yang berpotensi sebagai pemasok air banjir menggunakan metode teknik mitigasi bencana dan Sistem Informasi Geografis (SIG). Teknik mitigasi bencana membagi dua kajian utama, yakni kajian daerah rawan kebanjiran menggunakan parameter bentuk lahan, lahan kiri-kanan sungai, percabangan sungai, sinusitas sungai, bangunan air. Kajian daerah potensi pemasok air banjir menggunakan parameter hidrologi sungai yakni curah hujan, bentuk DAS, gradien sungai, kerapatan drainase, kemiringan lereng, penggunaan lahan. Analisis dilakukan dengan menggunakan metode skoring dan pembobotan. Sistem Informasi Geografis digunakan sebagai permodelan spasial dalam memetakan kerawanan dan potensi banjir menggunakan teknik overlay/intersect dan merepresentasikannya dalam bentuk peta
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