AIM: Biotic homogenization – the tendency for communities to converge in species composition – has occurred in many ecosystems, creating management challenges. The extent to which this convergence in ...species composition is related to convergence in trait composition (‘functional homogenization’), however, remains unresolved. LOCATION: North America, Wisconsin. METHODS: Using extensive plant community survey data from the 1950s and 2000s, and values for 11 traits measured on 169 species, we examined changes in functional beta diversity across 151 upland forest stands distributed across southern and northern Wisconsin. To estimate functional beta diversity, we used two recently developed pairwise functional dissimilarity metrics, plus an additive partitioning of functional diversity approach. RESULTS: Using pairwise functional dissimilarity metrics, we found no significant changes in functional beta diversity through time in either southern or northern upland forests. Under additive partitioning, species alpha diversity was lower than species beta diversity; whereas functional alpha diversity was much higher than functional beta diversity in both time periods and across all forest types. This suggests a high turnover of species but a low turnover of traits among communities. MAIN CONCLUSIONS: Although upland forests in Wisconsin have experienced taxonomic homogenization, they have not undergone functional homogenization, which may reflect a high functional redundancy among Wisconsin forest plants. As species decline further or disappear in response to habitat fragmentation and other global changes, functional redundancy may decline in a way that could diminish the functional diversity of Wisconsin's forests at both local and regional scales.
We present design and experimental results on novel antenna-integrated edge-coupled photodiodes, examining particularly their suitability as photomixers for broadband terahertz sources. We show that ...a simple "stub" detector positioned at the edge of the chip can yield promising overall performance when integrated with a number of different planar antennas specifically designed for this configuration. Using a slot-horn antenna connected via a coplanar line, we measure terahertz emission figures of 100 μW over the range 100-500 GHz, with 50 μW available at 750 GHz. We also present a novel planar double-horn antenna and show that with suitable use of terahertz "optics" this offers broadband through-substrate emission from 200 GHz to over 1 THz, with 10 μW terahertz power emitted at 1.004 THz.
A simple thermal treatment induced transition from Zn
(OH)
(BDC)
(MOF-69c) to Zn
O(BDC)
(MOF-5) is reported. Phase crystallinity, pore characteristics and hydrogen storage capacities of the resulting ...crystals were investigated. It is shown that the structural transition from Zn
(OH)
(BDC)
(MOF-69c) to Zn
O(BDC)
(MOF-5) could be induced by simply employing the optimal thermal treatment conditions of 200 °C for 48 h in open air. The resultant relatively lower specific surface area of MOF-5 crystals compared to MOF-69c was in agreement with the increased pore diameter and decreased hydrogen storage capacity at 1 bar and 77 K.
Insects may adopt a range of strategies such as diapause, migration and phenotypic plasticity to achieve maximal survival and reproduction in response to the environment. However, the phenotypic ...plasticity of voltinism in local populations of biological control agents is still poorly understood, making evaluation of biological control efficiency difficult. Here we report our two years’ work on a parasitic wasp,
Platygaster demades Walker (Hymenoptera: Platygasteridae), a parasitoid of apple leaf-curling midge,
Dasineura mali Kieffer (Diptera: Cecidomyiidae).
P. demades produces aestivating and non-aestivating phenotypes at the embryonic stage over the season. It regulates the frequency and duration of aestivating phenotypes from the late spring to mid autumn and adjusts the embryonic developmental rate of non-aestivating phenotypes from the early to late autumn, producing univoltine, bivoltine, trivoltine and quadrivoltine phenotypes over the season. The regulation of aestivation frequency and duration is a temporal risk-spreading strategy for maximal survival, i.e., when the future food source is expected to be short the wasp regulates its population by entering aestivation in a frequency and duration concordant with the expected scale and duration of food shortage to avoid massive mortality. This strategy helps maintain a large overwintering population size for the next season. The adjustment of the embryonic developmental rate for the non-aestivating phenotype from the early to late autumn is an adaptive developmental strategy for maximal synchronization with the host,
D. mali, i.e., the later the
D. mali larvae become mature, the faster the parasitoid embryos develop. This strategy ensures that both aestivated and non-aestivated individuals reach a complete synchronization with the emergence of their hosts in the next spring.
Abstract Ghana has a large informal work sector which makes up close to 85% of the urban economy (https://www.sciencedirect.com/science/article/pii/S2590291120300838). This sector has minimal ...regulated working conditions, with workers having to rely on seasonal or production demand-based work. WHWB is carrying out two projects in the informal sector in Ghana, namely, “Roadside Mechanics Shop Activities” and “Artisanal & Small-Scale Mining Activities”. These projects commenced in Q3 2022, and both projects should be completed and reported on by Q1 2024. These projects are being supported by WHWB, SKC UK, and the Belgian Center for Occupational Hygiene (BeCOH). An AIHA grant has been received for funding the Roadside Mechanics Shop Activities project, a WHWB International grant has been received for funding the Artisanal & Small-Scale Mining Activities project, and donations are also welcome via this GoFundMe link: https://gofund.me/e26ba537. The Ghanaian regulatory authorities, whilst keen to improve the regulation of these sectors, are currently not well-informed of occupational/industrial hygiene aspects and do not have the technical resources to recognise, evaluate or control workplace health exposures. The outcomes of these projects will be available to the Ghanaian regulatory authorities, to improve workplace health matters in these industrial sectors. The outcomes of these projects will help to increase the awareness of workplace health issues in these sectors and will allow the implementation of appropriate workplace control strategies to improve workplace health conditions. This presentation will describe both projects, the findings, challenges, and positive outcomes.
We present experimental results on the performance of antenna-integrated photodiodes intended for use as photomixers to provide a tunable broadband source of terahertz (THz) radiation. In a balanced ...strain-absorber structure, we show that the introduction of strain has proved effective in enhancing the performance at frequencies above 500 GHz. A comparison of strained and unstrained devices confirms this claim. These structures are integrated with a range of antennas, including log periodic and slot-horn types, designed for wideband THz emission. Using the devices as photomixers for the outputs from a DFB laser and an external cavity laser in the 1550 nm telecom window, tunable emission is demonstrated over the range from 100 GHz to 1.8 THz.
Correlates of post-traumatic growth (PTG) have been examined in the area of health psychology previously, with much focus on aspects of personality, coping, and social support. This systematic review ...aimed to examine correlates of PTG for those who have experienced a myocardial infarction (MI). Studies which met inclusion criteria were assessed for quality and reviewed. Results showed an inconsistent strength of associations between studies and so conclusions cannot be drawn. Possible reasons for these differences are discussed and recommendations for future research are suggested.
We report on advanced millimeter-wave (mm-wave) photonic components for broadband radio transmission. We have developed self-pulsating 60-GHz range quantum-dash Fabry-Perot mode-locked laser diodes ...(MLLD) for passive, i.e., unlocked, photonic mm-wave generation with comparably low-phase noise level of -76 dBc/Hz @ 100-kHz offset from a 58.8-GHz carrier. We further report on high-frequency 1.55-μm waveguide photodiodes (PD) with partially p-doped absorber for broadband operation (f 3dB ~70-110 GHz) and peak output power levels up to +4.5 dBm @ 110 GHz as well as wideband antenna integrated photomixers for operation within 30-300 GHz and peak output power levels of -11 dBm @ 100 GHz and 6-mA photocurrent. We further present compact 60-GHz wireless transmitter and receiver modules for wireless transmission of uncompressed 1080p (2.97 Gb/s) HDTV signals utilizing the developed MLLD and mm-wave PD. Error-free (BER = 10 -9 , 2 31 - 1 PRBS, NRZ) outdoor wireless transmission of 3 Gb/s over 25 m is demonstrated, as well as wireless transmission of uncompressed HDTV signals in the 60-GHz band. Finally, an advanced 60-GHz photonic wireless system offering record data throughputs and spectral efficiencies is presented. For the first time, we demonstrate photonic wireless transmission of data throughputs up to 27.04 Gb/s (EVM 17.6%) using a 16-QAM OFDM modulation format resulting in a spectral efficiency as high as 3.86 b/s/Hz. Wireless experiments were carried out within the regulated 57-64-GHz band in a lab environment with a maximum transmit power of - 1 dBm and 23 dBi gain antennas for a wireless span of 2.5 m. This span can be extended to some 100 m when using high-gain antennas and higher transmit power levels.
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