Remote sensing of the seasonal variation of coniferous forest structure and function

One of the objectives of the Oregon Transect Ecosystem Research (OTTER) project is the remotely sensed determination of the seasonal variation of leaf area index (LAI) and absorbed photosynthetically active radiation (APAR). These measurements are required for input into a forest ecosystem model which predicts net primary production evapotranspiration, and photosynthesis of coniferous forests. Details of the study are given

Multifaceted Faculty Network Design and Management: Practice and Experience Report

We report on our experience on multidimensional aspects of our faculty's network design and management, including some unique aspects such as campus-wide VLANs and ghosting, security and monitoring, switching and routing, and others. We outline a historical perspective on certain research, design, and development decisions and discuss the network topology, its scalability, and management in detail; the services our network provides, and its evolution. We overview the security aspects of the management as well as data management and automation and the use of the data by other members of the IT group in the faculty.Comment: 19 pages, 11 figures, TOC and index; a short version presented at C3S2E'11; v6: more proofreading, index, TOC, reference

Photoelectron spectra in strong-field ionization by a high frequency field

We analyze atomic photoelectron momentum distributions induced by bichromatic and monochromatic laser fields within the strong field approximation (SFA), separable Coulomb-Volkov approximation (SCVA), and ab initio treatment. We focus on the high frequency regime -- the smallest frequency used is larger than the ionization potential of the atom. We observe a remarkable agreement between the ab initio and velocity gauge SFA results while the velocity gauge SCVA fails to agree. Reasons of such a failure are discussed.Comment: Completely rewritten paper. Ionization by a two-color field is adde

General Time-Dependent Configuration-Interaction Singles I: The Molecular Case

We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in our treatment of this method, we present example calculations of strong-field ionization of helium, lithium hydride, water, and ethylene that demonstrate the utility of our implementation. The following companion paper specializes to the case of spherical symmetry, which is applied to various atoms

General Time-Dependent Configuration-Interaction Singles I: The Molecular Case

We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in our treatment of this method, we present example calculations of strong-field ionization of He, LiH, H2O, and C2H4 that demonstrate the utility of our implementation. The following paper [S. Carlström et al., following paper, Phys. Rev. A 106, 042806 (2022)] specializes to the case of spherical symmetry, which is applied to various atoms

Ultrafast slow-light: Raman-induced delay of THz-bandwidth pulses

We propose and experimentally demonstrate a scheme to generate optically-controlled delays based on off-resonant Raman absorption. Dispersion in a transparency window between two neighboring, optically-activated Raman absorption lines is used to reduce the group velocity of broadband 765 nm pulses. We implement this approach in a potassium titanyl phosphate (KTP) waveguide at room temperature, and demonstrate Raman-induced delays of up to 140 fs for a 650-fs duration, 1.8-THz bandwidth, signal pulse; the available delay-bandwidth product is $\approx1$. Our approach is applicable to single photon signals, offers wavelength tunability, and is a step toward processing ultrafast photons.Comment: 5+4 pages, 4+2 figure

Unmixing AVHRR Imagery to Assess Clearcuts and Forest Regrowth in Oregon

Advanced Very High Resolution Radiometer imagery provides frequent and low-cost coverage of the earth, but its coarse spatial resolution (approx. 1.1 km by 1.1 km) does not lend itself to standard techniques of automated categorization of land cover classes because the pixels are generally mixed; that is, the extent of the pixel includes several land use/cover classes. Unmixing procedures were developed to extract land use/cover class signatures from mixed pixels, using Landsat Thematic Mapper data as a source for the training set, and to estimate fractions of class coverage within pixels. Application of these unmixing procedures to mapping forest clearcuts and regrowth in Oregon indicated that unmixing is a promising approach for mapping major trends in land cover with AVHRR bands 1 and 2. Including thermal bands by unmixing AVHRR bands 1-4 did not lead to significant improvements in accuracy, but experiments with unmixing these four bands did indicate that use of weighted least squares techniques might lead to improvements in other applications of unmixing

Student Perspectives on improving mental health support Services at university

Drawing on thematic analysis of six student co‐creation panels, conducted during the Student Minds University Mental Health Charter consultations, this paper elucidates students’ perspectives and proposals regarding the current issues and challenges around university student mental health and well‐being support services. In particular, panels identified existing challenges and opportunities to improve support service access, strategy, and delivery. The panels generated a series of recommendations aimed to establish a clear, coordinated, and strategic approach to delivering accessible and inclusive student mental health support services that are responsive to the diverse needs of the whole student population. Significantly, the student panels situated service reforms within a ‘whole university approach’ entailing holistic structural and cultural change to the university environment, in order to enrich student mental health and well‐being and reduce demand on services. The findings of this paper can both reaffirm and specify the principles of good practice propounded by the University Mental Health Charter from a student perspective

Time-bin to Polarization Conversion of Ultrafast Photonic Qubits

The encoding of quantum information in photonic time-bin qubits is apt for long distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which co-polarized time-bins can be switched, other encodings, e.g. polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of 0.827+/-0.003 with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks