Dark state lasers

We propose a new type of laser resonator based on imaginary "energy-level splitting" (imaginary coupling, or quality factor Q splitting) in a pair of coupled microcavities. A particularly advantageous arrangement involves two microring cavities with different free-spectral ranges (FSRs) in a configuration wherein they are coupled by "far-field" interference in a shared radiation channel. A novel Vernier-like effect for laser resonators is designed where only one longitudinal resonant mode has a lower loss than the small signal gain and can achieve lasing while all other modes are suppressed. This configuration enables ultra-widely tunable single-frequency lasers based on either homogeneously or inhomogeneously broadened gain media. The concept is an alternative to the common external cavity configurations for achieving tunable single-mode operation in a laser. The proposed laser concept builds on a high-Q "dark state" that is established by radiative interference coupling and bears a direct analogy to parity-time (PT) symmetric Hamiltonians in optical systems. Variants of this concept should be extendable to parametric-gain based oscillators, enabling use of ultrabroadband parametric gain for widely tunable single-frequency light sources

Comparison of the Glover-Balmer solution with a calibrated groundwater model to estimate aquifer-stream interactions in an irrigated alluvial valley

2014 Fall.Includes bibliographical references.In many alluvial valleys wherein streams are hydraulically connected to the aquifer system, understanding and quantifying the impact of aquifer stresses (e.g. pumping, injection, recharge) on streamflow is of primary importance. Due to their relative simplicity and straightforward application, analytical models such as the Glover-Balmer solution often are employed to quantify these impacts. However, the predictive capacity of such models in intensively-irrigated systems, wherein canals, spatially-varying irrigation application patterns, and spatially-variable aquifer characteristics are often present, is not well known. In this study, the Glover-Balmer solution is compared to a calibrated MODFLOW-UZF numerical model for a study area within the Lower Arkansas River Valley in southeastern Colorado, USA. Comparison is made by simulating field-scale water extraction, addition, and fallowing scenarios, and comparing the predictions by both models of stream depletion or accretion. To create an ideal comparison, inputs to the Glover-Balmer model (stress, aquifer parameters) are obtained from the calibrated numerical model. Results for a few fallowing scenarios and from 52 extraction and addition scenarios from a variety of distances from the Arkansas River show that, under certain circumstances, the two models have good agreement in results, particularly in regions close (< about 0.5 to 1 km) to the river. However, due to aquifer heterogeneity and the overall hydrologic complexity in the natural system, results of the two models often diverge, with the Glover-Balmer model typically estimating greater impacts on the stream than the MODFLOW-UZF model. Suggested considerations are given for applying the Glover-Balmer solution, including the consideration of hydrologic components that may intercept or contribute to groundwater flow (such as irrigation canals, upflux to ET, groundwater storage, and tributaries), the potential influence of unsaturated zone processes, and changes in depletion/accretion locations and timing due to aquifer heterogeneity

Method for Solving State-Path Constrained Optimal Control Problems Using Adaptive Radau Collocation

A new method is developed for accurately approximating the solution to state-variable inequality path constrained optimal control problems using a multiple-domain adaptive Legendre-Gauss-Radau collocation method. The method consists of the following parts. First, a structure detection method is developed to estimate switch times in the activation and deactivation of state-variable inequality path constraints. Second, using the detected structure, the domain is partitioned into multiple-domains where each domain corresponds to either a constrained or an unconstrained segment. Furthermore, additional decision variables are introduced in the multiple-domain formulation, where these additional decision variables represent the switch times of the detected active state-variable inequality path constraints. Within a constrained domain, the path constraint is differentiated with respect to the independent variable until the control appears explicitly, and this derivative is set to zero along the constrained arc while all preceding derivatives are set to zero at the start of the constrained arc. The time derivatives of the active state-variable inequality path constraints are computed using automatic differentiation and the properties of the chain rule. The method is demonstrated on two problems, the first being a benchmark optimal control problem which has a known analytical solution and the second being a challenging problem from the field of aerospace engineering in which there is no known analytical solution. When compared against previously developed adaptive Legendre-Gauss-Radau methods, the results show that the method developed in this paper is capable of computing accurate solutions to problems whose solution contain active state-variable inequality path constraints.Comment: 31 pages, 7 figures, 5 table

Seagrasses (Zostera marina) and (Zostera japonica) Display a Differential Photosynthetic Response to TCO2: Implications for Acidification Mitigation

Excess atmospheric CO2 is being absorbed at an unprecedented rate by the global and coastal oceans, shifting the baseline pCO2 and altering seawater carbonate chemistry in a process known as ocean acidification (OA). Recent attention has been given to near-shore vegetated habitats, such as seagrass beds, which may have the potential to mitigate the effects of acidification on vulnerable calcifying organisms via photosynthesis. Seagrasses are capable of raising seawater pH and calcium carbonate saturation state during times of high photosynthetic activity. To better understand the photosynthetic potential of seagrass OA mitigation, we exposed Pacific Northwest populations of native Zostera marina and non-native Zostera japonica seagrasses from Padilla Bay, WA, to various irradiance and total CO2 (TCO2) concentrations ranging from ~1770 – 2100 μmol TCO2 kg-1. Our results indicate that the maximum net photosynthetic rate (Pmax) for Z. japonica as a function of irradiance and TCO2 was 3x greater than Z. marina when standardized to chlorophyll (360 ± 74 μmol TCO2 mgchl-1 hr-1 and 113 ± 21 μmol TCO2 mgchl-1 hr-1, respectively). In addition, Z. japonica increased its Pmax 77% (± 56%) when TCO2 increased from ~1770 to 2050 μmol TCO2 kg-1, whereas Z. marina did not display an increase in Pmax with higher TCO2. The lack of response by Z. marina to TCO2 is a departure from previous findings; however, it is likely that the variance within our treatments (coefficient of variation: 30 – 60%) obscured any positive effect of TCO2 on Z. marina given the range of concentrations tested. Because previous findings have shown that Z. marina is saturated with respect to HCO3- at low pH (≥ 7.5) we, therefore, suggest that the unequivocal positive response of Z. japonica to TCO2 is a result of increased HCO3- utilization in addition to increased CO2 uptake. Considering that Z. japonica displays a greater photosynthetic rate than Z. marina when normalized to chlorophyll, particularly under enhanced TCO2 conditions, the ability of Z. japonica to mitigate OA may also increase relative to Z. marina in the future ocean. Higher photosynthetic rates by Z. japonica result in a greater potential, on a per chlorophyll basis, to increase pH and calcium carbonate saturation state—both of which affect acid-base regulation and calcification of calcifying organisms vulnerable to acidification. While it is important to consider genotypic differences throughout Z. marina and Z. japonica’s biogeographical distribution, our findings help elucidate the potential contribution both seagrasses have on variations in carbonate chemistry. Further, our results could be applied to ecosystem service models aimed at determining how specific seagrass species can be grown in a controlled setting to help mitigate OA hotspots that affect commercial shellfish aquaculture

Noncompleted Sexual Offenses: Internal States, Risks and Difficulties Related to Crime Commission through the Lens of Sexual Offenders

The study aims to generate insights from sexual offenders on the influence of internal states and how they perceive risks of apprehension and difficulties in the context of noncompleted sexual offenses, that is when offenders initiated the offense but were stopped or discouraged either before or during sexual contact. Adult males incarcerated for sexually offending completed a self-report questionnaire. Regression models, including interaction effects, were estimated. Two interaction effects were found providing insights into which and how internal states, such as intoxication to alcohol, may influence perceived difficulties related to crime. Future research should promote the investigation of noncompleted sexual offenses, which could provide a real opportunity to generate new or complementary insights for better understanding and guiding prevention initiatives

Diurnal variations in the corrosiveness and acidification of porewater and its effects on populationdynamics of marine bivalves

The undergradtuate research project was the completion, manipulation and assessment of a population model. The stage based population model assessed the late larval and juveniles stages of the hard shell clam Mercenaria mercenaria. There were seven class sizes input into the model starting with pediveligers and ending with juveniles at specific developmental sizes: ~0.2mm(Pediveliger), ~0.2mm+ (Dissoconch I) and ~1.0mm+ (Dissoconch II). Parameters or vital rates input into the model included growth, survival and saturation state. The aim of the model was to investigate by what degree the saturation state of CaCO3 (Ωaragonite) influences the population dynamics of Mercenaria mercenaria. My project involved adding the seventh class size to the model, and changing the constant value of saturation state to a variable parameter on a diurnal cycle. Additionally, the assessment of the model output would be the focus of the research. The model was constructed in matlab, so the learning this software was necessary for the manipulation and completion of this model. The vital rates of survival and growth were probabilities defined from lab and field experiments published in the literature. Saturation state was incorporated into these probabilities as a way to change the values according to environmental conditions. The task of parameterizing saturation state as a cyclical function meant the reworking of how model probabilities were populated. Writing the function and integrating the varying saturation states to each time step was the dominate focus of the project before analysis. Background literature was necessary in order to establish a range of saturation state (Ω) values to input into the model. With accurate values of saturation state obtained, three different simulation trials were run to represent the diurnal variation. The simulations ranged from high (0.20 – 2.20), medium (0.54 – 1.86) and low (0.87 -1.53). The values represent amplitudes of 0.33, 0.66 and 1.0 within a diurnal cycle. By assessing the different simulation runs all with the same mean value of 1.2, the characterization of dramatic shifts could be compared amongst the three simulation runs. Assessing the degree of change this variation had on the population was the main objective for the model output. Once the model was completed the objectives included: assessing what stage class had the highest sensitivity to changes in vital rates, evaluation of hourly mortality rates given varying diurnal cycles in saturation state, identifying specific time in days that the population reaches stable age distribution and survivors converge to ultimate size class, and compare population growth rate of large diurnal shifts or small shifts at constant undersaturation. The output of the model provided the necessary data to assess the population dynamics and answer the above objectives. Analysis of the data was completed in matlab and Microsoft excel. Future work for this model will be to create a separate carbonate chemistry which will run in parallel with the population model. The objective of this carbonate chemistry model will be to parameterize saturation state more completely by the components that constitute what saturation state is

C1 inhibitor deficiency: 2014 United Kingdom consensus document

C1 inhibitor deficiency is a rare disorder manifesting with recurrent attacks of disabling and potentially life-threatening angioedema. Here we present an updated 2014 United Kingdom consensus document for the management of C1 inhibitor-deficient patients, representing a joint venture between the United Kingdom Primary Immunodeficiency Network and Hereditary Angioedema UK. To develop the consensus, we assembled a multi-disciplinary steering group of clinicians, nurses and a patient representative. This steering group first met in 2012, developing a total of 48 recommendations across 11 themes. The statements were distributed to relevant clinicians and a representative group of patients to be scored for agreement on a Likert scale. All 48 statements achieved a high degree of consensus, indicating strong alignment of opinion. The recommendations have evolved significantly since the 2005 document, with particularly notable developments including an improved evidence base to guide dosing and indications for acute treatment, greater emphasis on home therapy for acute attacks and a strong focus on service organisation. This article is protected by copyright. All rights reserved

TOI-431/HIP 26013: A super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet

We present the bright (Vmag = 9.12), multiplanet system TOI-431, characterized with photometry and radial velocities (RVs). We estimate the stellar rotation period to be 30.5 \ub1 0.7 d using archival photometry and RVs. Transiting Exoplanet Survey Satellite (TESS) objects of Interest (TOI)-431 b is\ua0a\ua0super-Earth with\ua0a\ua0period of 0.49 d,\ua0a\ua0radius of 1.28 \ub1 0.04 R,\ua0a\ua0mass of 3.07 \ub1 0.35 M, and\ua0a\ua0density of 8.0 \ub1 1.0 g cm-3; TOI-431 d is\ua0a\ua0sub-Neptune with\ua0a\ua0period of 12.46 d,\ua0a\ua0radius of 3.29 \ub1 0.09 R,\ua0a\ua0mass of 9.90+1.53-1.49 M, and\ua0a\ua0density of 1.36 \ub1 0.25 g cm-3. We find\ua0a\ua0third planet, TOI-431 c,\ua0in\ua0the High Accuracy Radial velocity Planet Searcher RV data, but it is not seen to transit\ua0in\ua0the TESS light curves. It has an Msin i of 2.83+0.41-0.34 M, and\ua0a\ua0period of 4.85 d. TOI-431 d likely has an extended atmosphere and is one of the most well-suited TESS discoveries for atmospheric characterization, while the super-Earth TOI-431 b may be\ua0a\ua0stripped core. These planets straddle the radius gap, presenting an interesting case-study for atmospheric evolution, and TOI-431 b is\ua0a\ua0prime TESS discovery for the study of rocky planet phase curves