Measurement of solar UVB exposures in sea water with a high exposure dosimeter

For several decades, marine scientists have investigated the underwater ultraviolet light environment using a wide variety of spectroradiometric and radiometric equipment. These types of instruments are extremely useful for taking underwater measurements of the solar UV within a short window of time, for example recording fluctuations in UV levels caused by rapidly changing environmental parameters, like cloud cover or water turbidity. However, over long phases these spectroradiometers and radiometers become increasingly problematic to use, with high amounts of maintenance time necessary involving routine calibrations and corrections for the immersion effect. However, to supplement the short – term underwater measurements using spectroradiometers and radiometers, a new long – term dosimetric system employing Poly (2,6-dimethyl-1, 4-phenylene oxide) (PPO) film has been developed. The PPO film dosimeter has proven to be capable of measuring underwater UV dosages of at least five times that of the more commonly used polysulphone dosimeter, at a level of accuracy close to what would be expected of dosimetric measurements made in air provided that the necessary calibrations are completed correctly. This presentation details a measurement campaign made in a simulated sea water environment using a batch of PPO dosimeters set at different depths and aligned to a range of different inclinations and azimuths by means of attachment to a custom built dosimeter submersible float (DSF) unit. The results obtained from this measurement campaign were used to compute a diffuse attenuation coefficient (Kd) for the sea water. This Kd value was compared to a Kd value derived from results taken using a radiometer in the same water

Alternative methods for the reduction of evaporation: practical exercises for the science classroom

Across the world, freshwater is valued as the most critically important natural resource, as it is required to sustain the cycle of life. Evaporation is one of the primary environmental processes that can reduce the amount of quality water available for use in industrial, agricultural and household applications. The effect of evaporation becomes intensified especially during conditions of drought, particularly in traditionally arid and semi-arid regions, such as those seen in a number of countries over the past 10 years. In order to safeguard against the influence of droughts and to save water from being lost to the evaporative process, numerous water saving mechanisms have been developed and tested over the past century. Two of the most successful and widely used mechanisms have included floating hard covers and chemical film monolayers. This paper describes a laboratory based project developed for senior high school and first year university classes, which has been designed to introduce students to the concepts of evaporation, evaporation modelling and water loss mitigation. Specifically, these ideas are delivered by simulating the large-scale deployment of both monolayers and floating hard covers on a small water tank under numerous user defined atmospheric and hydrodynamic conditions, including varying surface wind speeds and underwater bubble plumes set to changing flow rates

An experimental test of processes underlying self-disclosure in computer-mediated communication

A consistent finding in computer-mediated communication (CMC) and Internet research is that, compared to face-toface communication, CMC results in higher levels of self-disclosure. We identified four possible mediators that may carry the influence of CMC on self-disclosure: self-presentation, similarity, self-awareness, and direct questioning. The validity of these mediators was tested in an experiment in which 81 cross-sex dyads were randomly assigned to three experimental conditions: a text-only CMC condition, a visual CMC condition, and a face-to-face condition. Selfdisclosure was lower in the face-to-face condition than in the text-only CMC condition and the visual CMC condition. Between the two CMC conditions, no differences in self-disclosure were found. Of the four possible mediators, only direct questioning mediated the effect of CMC on self-disclosure. CMC dyads engaged in more direct questioning and therefore displayed higher levels of self-disclosure

Connecting the Concepts of Frugality and Inclusion to Appraise Business Practices in Systems of Food Provisioning:A Kenyan Case Study

Small and medium size business enterprises (SMEs) are the linchpin in systems of food provisioning in sub-Saharan Africa. These businesses occupy the middle of the agri-food chain and face a food security conundrum: they must ensure that smallholder producers of limited means can operate under fair terms while low-income consumers are supplied with affordable and nutritious food. This task becomes even more challenging when resources are scarce. This paper explores how resource-constrained SMEs arrange the terms on which both farmers and consumers are included in agri-food chains. To this end, it combines the concept of inclusion with that of frugality. We use the case of a Kenyan SME to demonstrate how a focus on frugality can advance our understanding of how business practices create thriving business relationships with smallholders while simultaneously ensuring access to affordable food for consumers. We additionally identify what conditions for inclusion emerge from this type of dynamic business practices. Our perspective departs from assessing induced organisational interventions, such as contract farming or cooperatives, which deliberately shorten the agri-food chain, thereby overlooking the skilful practices being employed by business actors in the middle of the chain.</p

Annual measurement of solar UVB at a reef site using a polyphenylene oxide dosimeter

Numerous investigations detailed over the last thirty years have highlighted how solar UV (290-400 nm) can have a detrimental effect on coral health. It has also been postulated that coral bleaching is caused by a synergistic process between high water temperatures and increases in UV. As a consequence of its influence upon coral ecosystems, UV radiation must be monitored in underwater locations using an appropriate non-invasive measurement technique in order to better understand the damage it causes on both a macro and micro scale and provide solutions on how to adequately manage its impact. The high energy UVB waveband (290-320 nm) is believed to have the greatest negative influence on coral stress. This report details the employment of a simple, easily deployable UVB measuring dosimeter system based on polyphenylene oxide (PPO) at a coral reef location near Hervey Bay (25°17 S, 152°52′ E) over the interval of one year. Continual deployment of the PPO dosimeters measured a clear inverse correlation between tide level and UVB penetration, with the highest coral UVB exposures measured during the months of winter and spring (coinciding with typically lower tidal conditions during this time). This suggests that the UVB incident on Queensland coral reefs may not be strictly dependent on solar zenith angle (the Sun’s position in the sky), which is generally the primary factor in determining the extent of terrestrial UVB exposures. Further, this may mean that photo-damage incident on corals could be exacerbated in traditionally cooler months if current global warming trends continue

Arc-continent collisions, sediment recycling and the maintenance of the continental crust

Author Posting. © Geological Society of London, 2009. This is the author's version of the work. It is posted here by permission of Geological Society of London for personal use, not for redistribution. The definitive version was published in Geological Society, London, Special Publications 318 (2009): 75-103, doi:10.1144/SP318.3.Subduction zones are both the source of most new continental crust and the locations where crustal material is returned to the upper mantle. Globally the total amount of continental crust and sediment subducted below forearcs currently lies close to 3.0 Armstrong Units (1 AU = 1 km3/yr), of which 1.65 AU comprises subducted sediments and 1.33 AU tectonically eroded forearc crust. This compares with average ~0.4 AU lost during subduction of passive margins during Cenozoic continental collision. Individual margins may retreat in a wholesale, steady-state mode, or in a slower way involving the trenchward erosion of the forearc coupled with landward underplating, such as seen in the central and northern Andean margins. Tephra records of magmatism evolution from Central America indicate pulses of recycling through the roots of the arc. While this arc is in a state of long- term mass loss this is achieved in a discontinuous fashion via periods of slow tectonic erosion and even sediment accretion interrupted by catastrophic erosion events, likely caused by seamount subduction. Crustal losses into subduction zones must be balanced by arc magmatism and we estimate global average melt production rates to be 96 and 64 km3/m.y./km in oceanic and continental arc respectively. Key to maintaining the volume of the continental crust is the accretion of oceanic arcs to continental passive margins. Mass balancing across the Taiwan collision zones suggests that almost 90% of the colliding Luzon Arc crust is accreted to the margin of Asia in that region. Rates of exhumation and sediment recycling indicate the complete accretion process spans only 6–8 m.y. Subduction of sediment in both erosive and inefficient accretionary margins provides a mechanism for returning continental crust to the upper mantle. Sea level governs rates of continental erosion and thus sediment delivery to trenches, which in turn controls crustal thicknesses over 107– 109 yrs. Tectonically thickened crust is reduced to normal values (35–38 km) over timescales of 100–200 Ma.PC wishes to thank the Alexander von Humboldt Foundation for support during the writing of this paper at the University of Bremen, as well as the College of Physical Sciences, University of Aberdeen for its generous support

Human-Centered Computer Vision

Contains fulltext : 241512.pdf (Publisher’s version ) (Open Access)Symposium on The Art and Science of Pattern Recognitio

Reasoning about Ambiguous Definite Descriptions

Natural language reasoning plays an increasingly important role in improving language models' ability to solve complex language understanding tasks. An interesting use case for reasoning is the resolution of context-dependent ambiguity. But no resources exist to evaluate how well Large Language Models can use explicit reasoning to resolve ambiguity in language. We propose to use ambiguous definite descriptions for this purpose and create and publish the first benchmark dataset consisting of such phrases. Our method includes all information required to resolve the ambiguity in the prompt, which means a model does not require anything but reasoning to do well. We find this to be a challenging task for recent LLMs. Code and data available at: https://github.com/sfschouten/exploiting-ambiguityComment: EMNLP 2023 Finding