Showing papers by "University of Greenwich published in 2017"

The Meaning, Antecedents and Outcomes of Employee Engagement: A Narrative Synthesis

Abstract: The claim that high levels of engagement can enhance organizational performance and individual well-being has not previously been tested through a systematic review of the evidence. To bring coherence to the diffuse body of literature on engagement, the authors conducted a systematic synthesis of narrative evidence involving 214 studies focused on the meaning, antecedents and outcomes of engagement. The authors identified six distinct conceptualizations of engagement, with the field dominated by the Utrecht Group's ‘work engagement’ construct and measure, and by the theorization of engagement within the ‘job demands–resources’ framework. Five groups of factors served as antecedents to engagement: psychological states; job design; leadership; organizational and team factors; and organizational interventions. Engagement was found to be positively associated with individual morale, task performance, extra-role performance and organizational performance, and the evidence was most robust in relation to task performance. However, there was an over-reliance on quantitative, cross-sectional and self-report studies within the field, which limited claims of causality. To address controversies over the commonly used measures and concepts in the field and gaps in the evidence-base, the authors set out an agenda for future research that integrates emerging critical sociological perspectives on engagement with the psychological perspectives that currently dominate the field.

Genome sequencing of the sweetpotato whitefly Bemisia tabaci MED/Q

Abstract: National Natural Science Foundation of China [31420103919, 31672032]; Chinese Academy of Agricultural Sciences (CAAS-ASTIP-IVFCAAS) the China Agriculture Research System [CARS-26-10]; Beijing Training Project for the Leading Talents in S T [LJRC201412]; Beijing Key Laboratory for Pest Control and Sustainable Cultivation of Vegetables; Beijing Nova Program [Z171100001117039]

Smallholder farmers’ adaptation to climate change and determinants of their adaptation decisions in the Central Rift Valley of Ethiopia

Abstract: The agricultural sector remains the main source of livelihoods for rural communities in Ethiopia, but faces the challenge of changing climate. This study investigated how smallholder farmers perceive climate change, what adaptation strategies they practice, and factors that influence their adaptation decisions. Both primary and secondary data were used for the study, and a multinomial logit model was employed to identify the factors that shape smallholder farmers’ adaptation strategies. The results show that 90% of farmers have already perceived climate variability, and 85% made attempts to adapt using practices like crop diversification, planting date adjustment, soil and water conservation and management, increasing the intensity of input use, integrating crop with livestock, and tree planting. The econometric model indicated that education, family size, gender, age, livestock ownership, farming experience, frequency of contact with extension agents, farm size, access to market, access to climate information and income were the key factors determining farmers’ choice of adaptation practice. In the Central Rift Valley of Ethiopia, climate change is a pressing problem, which is beyond the capacity of smallholders to respond to autonomously. Farmers’ capacity to choose effective adaptation options is influenced by household demography, as well as positively by farm size, income, access to markets, access to climate information and extension, and livestock production. This implies the need to support the indigenous adaptation strategies of the smallholder farmers with a wide range of institutional, policy, and technology support; some of it targeted on smaller, poorer or female-headed households. Moreover, creating opportunities for non-farm income sources is important as this helps farmers to engage in those activities that are less sensitive to climate change. Furthermore, providing climate change information, extension services, and creating access to markets are crucial.

Living like a local: Authentic tourism experiences and the sharing economy

Abstract: Travellers are demanding authentic, experientially-oriented opportunities with more meaningful interactions with locals. The sharing economy has emerged partly as a response to these consumer trends with major potential impacts for tourism. This research investigated the phenomenon of authenticity-seeking tourism and its links to the hospitality sector through consumer choices related to accommodation offered by sharing economy providers. It explored the relationship between perceived authenticity of the “local” experience and its significance when purchasing accommodation. The three themes of unique accommodation interiors and atmosphere, interactions with hosts, and interactions with local culture were found to be important to Airbnb users.

High prevalence of erectile dysfunction in diabetes: a systematic review and meta-analysis of 145 studies

Abstract: Erectile dysfunction may be common among men with diabetes, but its prevalence is still debated. We aimed to assess the relative prevalence of erectile dysfunction in diabetes searching major databases from inception to November 2016 for studies reporting erectile dysfunction in men with Type 1 and Type 2 diabetes mellitus. We conducted a meta-analysis of the prevalence [and 95% confidence intervals (95% CIs)] of erectile dysfunction in diabetes compared with healthy controls, calculating the relative odds ratios (ORs) and 95% CIs. A random effect model was applied. From 3747 initial hits, 145 studies were included representing 88 577 men (age: 55.8 ` 7.9 years). The prevalence of erectile dysfunction in diabetes overall was 52.5% (95% CI, 48.8 to 56.2) after adjusting for publication bias, and 37.5%, 66.3% and 57.7% in Type 1, Type 2 and both types of diabetes, respectively (P for interaction < 0.0001). The prevalence of erectile dysfunction was highest in studies using the Sexual Health Inventory for Men (82.2%, 17 studies, P for interaction < 0.0001). Studies with a higher percentage of people with hypertension moderated our results (beta = 0.03; 95% CI, 0.008 to 0.040; P = 0.003; R2 = 0.00). Compared to healthy controls (n = 5385) men with diabetes (n = 863) were at increased odds of having erectile dysfunction (OR 3.62; 95% CI, 2.53 to 5.16; P < 0.0001; I2 = 67%, k = 8). Erectile dysfunction is common in diabetes, affecting more than half of men with the condition and with a prevalence odds of approximately 3.5 times more than controls. Our findings suggest that screening and appropriate intervention for men with erectile dysfunction is warranted.

Plant secondary metabolites in nectar: impacts on pollinators and ecological functions

Abstract: 1. The ecological function of secondary metabolites in plant defence, against herbivores is well established, but their role in plant-pollinator interactions is less obvious. Nectar is the major reward for pollinators, so the occurrence of defence compounds in the nectar of many species is unexpected. However, increasing evidence supports a variety of potential benefits for both plant and pollinator from these components. 2. Secondary metabolites in nectar can be toxic or repellent to flower visitors, but they can also go undetected or make nectar attractive . For example, caffeine in nectar improves pollinator memory for cues associated with food rewards and enhances pollen transfer. All of these effects depend on the concentration of nectar metabolites so should be evaluated experimentally at a range of ecologically relevant doses. 3. Beneficial effects may include the following: a) increasing specialization in plant-pollinator interactions, b) protecting nectar from robbery or larceny, and c) preservation of nutrients in nectar from microbial degradation and reducing microbial disease levels in flower visitors. 4. This review synthesises evidence from recent literature that supports selection for secondary metabolites in floral nectar as an adaptation that drives the co-evolution between plants and their pollinators. However, their presence in nectar could simply be a consequence of their occurrence elsewhere in the plant for defence (pleiotropy). We draw attention to the need for studies demonstrating benefits to the plant, the importance of levels of exposure and a effects on target species beyond the current emphasis on alkaloids and bees.

A Shared-Aperture Dual-Band Dual-Polarized Filtering-Antenna-Array With Improved Frequency Response

Abstract: In this paper, a novel dual-band dual-polarized array antenna with low frequency ratio and integrated filtering characteristics is proposed. By employing a dual-mode stub-loaded resonator (SLR) to feed and tune with two patches, the two feed networks for each polarization can be combined, resulting in the reduction of the feed networks and the input ports. In addition, owing to the native dual resonant features of the SLR, the proposed antenna exhibits second-order filtering characteristics with improved bandwidth and out-of-band rejections. The antenna is synthesized and the design methodology is explained. The coupling coefficients between the SLR and the patches are investigated. To verify the design concept, a C-/X-band element and a $2 \times 2$ array are optimized and prototyped. Measured results agree well with the simulations, showing good performance in terms of bandwidth, filtering, harmonic suppression, and radiation at both bands. Such an integrated array design can be used to simplify the feed of a reflector antenna. To prove the concept, a paraboloid reflector fed by the proposed array is conceived and measured directivities of 24.6 dBi (24.7 dBi) and 28.6 dBi (29.2 dBi) for the X-polarization (Y-polarization) are obtained for the low- and high-band operations, respectively.

Comparing smallholder farmers’ perception of climate change with meteorological data: A case study from southwestern Nigeria

Abstract: This paper examines smallholder farmers’ perceptions of climate change, climate variability and their impacts, and adaptation strategies adopted over the past three decades. We use ethnographic analysis, combined with Cumulative Departure Index (CDI), Rainfall Anomaly Index (RAI) analysis, and correlation analysis to compare farmers’ perceptions in Southwestern Nigeria with historical meteorological data, in order to assess the way farmers’ observations mirror the climatic trends. The results show that about 67% of farmers who participated had observed recent changes in climate. Perceptions of rural farmers on climate change and variability are consistent with the climatic trend analysis. RAI and CDI results illustrate that not less than 11 out of 30 years in each study site experienced lower-than-normal rainfall. Climatic trends show fluctuations in both early growing season (EGS) and late growing season (LGS) rainfall and the 5-year moving average suggests a reduction in rainfall over the 30 years. Climatic trends confirmed farmers’ perceptions that EGS and LGS precipitations are oscillating, that rainfall onset is becoming later, and EGS rainfall is reducing. Overall impacts of climate change on both crops and livestock appear to be highly negative, much more on maize (62.8%), yam (52.2%), poultry (67%) and cattle (63.2%). Years of farming experiences and level of income of farmers appear to have a significant relationship with farmers’ choice of adaptation strategies, with r≥0.60@ p

Time reclaimed: temporality and the experience of meaningful work

Abstract: The importance of meaningful work has been identified in scholarly writings across a range of disciplines. However, empirical studies remain sparse and the potential relevance of the concept of temporality, hitherto somewhat neglected even in wider sociological studies of organizations, has not been considered in terms of the light that it can shed on the experience of work as meaningful. These two disparate bodies of thought are brought together to generate new accounts of work meaningfulness through the lens of temporality. Findings from a qualitative study of workers in three occupations with ostensibly distinct temporal landscapes are reported. All jobs had the potential to be both meaningful and meaningless; meaningfulness arose episodically through work experiences that were shared, autonomous and temporally complex. Schutz’s notion of the ‘vivid present’ emerged as relevant to understanding how work is rendered meaningful within an individual’s personal and social system of relevances.

Dietary Anthocyanins and Insulin Resistance: When Food Becomes a Medicine

Abstract: Insulin resistance is an abnormal physiological state that occurs when insulin from pancreatic β-cells is unable to trigger a signal transduction pathway in target organs such as the liver, muscles and adipose tissues. The loss of insulin sensitivity is generally associated with persistent hyperglycemia (diabetes), hyperinsulinemia, fatty acids and/or lipid dysregulation which are often prevalent under obesity conditions. Hence, insulin sensitizers are one class of drugs currently employed to treat diabetes and associated metabolic disorders. A number of natural products that act through multiple mechanisms have also been identified to enhance insulin sensitivity in target organs. One group of such compounds that gained interest in recent years are the dietary anthocyanins. Data from their in vitro, in vivo and clinical studies are scrutinized in this communication to show their potential health benefit through ameliorating insulin resistance. Specific mechanism of action ranging from targeting specific signal transduction receptors/enzymes to the general antioxidant and anti-inflammatory mechanisms of insulin resistance are presented.

Failure and Reliability Analysis of a SiC Power Module Based on Stress Comparison to a Si Device

Abstract: The superior electro-thermal properties of silicon carbide (SiC) power devices permit higher temperature of operation and enable higher power density compared with silicon devices. Nevertheless, the reliability of SiC power modules has been identified as a major area of uncertainty in applications which require high reliability. Traditional power module packaging methods developed for silicon chips have been adopted for SiC and the different thermomechanical properties cause different fatigue stresses on the solder layer of the chip. In this paper, a 2-D finite element model has been developed to evaluate the stress performance and lifetime of the solder layer for Si devices, which has been validated using accelerated power cycling tests on Si IGBTs. The proposed model was extrapolated for SiC devices of the same voltage and current rating using the same solder material and the results show that under the same cyclic power loss profile the induced stress and strain energy in the die attach layer is much higher and concentrates on the die/solder interfacial area for SiC chips. Using the validated stress-based model, the lifetime can be quantified when SiC chips are used. This ability to extrapolate the available power cycling and lifetime data of silicon chips to SiC chips would be a key element for developing reliable packaging methods for SiC devices.

Dual-Band Circularly Polarized Shared-Aperture Array for $C$ -/ $X$ -Band Satellite Communications

Abstract: A novel method of achieving a single-feed circularly polarized (CP) microstrip antenna with both broad impedance bandwidth and axial ratio (AR) bandwidth is presented. The CP characteristics are generated by employing a resonator to excite the two orthogonal modes of the patch via two coupling paths and the required 90° phase difference is achieved by using the different orders of the two paths. The presented method, instead of conventional methods that power dividers and phase delay lines are usually required, not only significantly enhances the bandwidths of the antenna but also results in a compact feed, reduced loss and high gain. Based on this method, a dual-band shared-aperture CP array antenna is implemented for $C$ -/ $X$ -band satellite communications. The antenna aperture includes a $2 \times 2$ array at $C$ -band and a $4 \times 4$ array at $X$ -band. To accommodate the $C$ - $X$ -band elements into the same aperture while achieving a good isolation between them, the $C$ -band circular patches are etched at the four corners. The measured results agree well with the simulations, showing a wide impedance bandwidth of 21% and 21.2% at $C$ -band and $X$ -band, respectively. The $C$ -band and $X$ -band 3 dB AR bandwidths are 13.2% and 12.8%. The array also exhibits a high aperture efficiency of over 55%, low sidelobe ( $C$ -band: −12.5 dB and $X$ -band: −15 dB), and high gain ( $C$ -band: 14.5 dBic and $X$ -band: 17.5 dBic).

Neuroprotective Effects of Citrus Fruit-Derived Flavonoids, Nobiletin and Tangeretin in Alzheimer's and Parkinson's Disease.

Abstract: Neurodegenerative diseases, namely Alzheimer's disease and Parkinson's disease represent a deleterious impact worldwide. Despite extensive preclinical and clinical research in neurodegenerative disorders, therapeutic strategies aimed at the prevention and chronic treatment of neurodegenerative conditions have not been successfully translated to the clinic. Therefore, the identification of novel pharmacological intervention derived from natural products is warranted. Nobiletin and tangeretin are important citrus flavonoids derived from the peel and other parts of Citrus L. genus, and have been shown to exhibit neuroprotective effects in several in vitro and in vivo studies. Apart from there antioxidant and anti-inflammatory effects, nobiletin and tangeretin have been shown to attenuate cholinergic deficits, reduce the abnormal accumulation of neurotoxic amyloid-beta peptides, reverse N-methyl- D-aspartate (NMDA) receptor hypofunction, ameliorate ischemic injury, inhibit hyperphosphorylation of tau protein, enhance neprilysin levels, modulate several signaling cascades, and protect against 1-methyl-4-phenylpyridinium (MPP(+)) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity. Taken together, these naturally occurring phytochemicals may represent beneficial drug candidates for the treatment and prevention of Alzheimer's and Parkinson's disease.

Broadband High-Gain Beam-Scanning Antenna Array for Millimeter-Wave Applications

Abstract: A novel method of achieving low profile, broadband microstrip array antennas with high antenna gain is proposed for millimeter-wave applications. The element employs a novel third-order vertically coupled resonant structure that a U-slot resonator in the ground is used to couple with the feeding resonator and the radiating patch, simultaneously. This proposed structure can significantly improve the bandwidth and frequency selectivity without increasing the thickness of the antenna. Then, to achieve the subarray, a new wideband power divider with loaded resonators is employed, which can be used to further improve the bandwidth. To demonstrate the working schemes of broadside radiation and scanned beam, two $4 \times 4$ array antennas are implemented on the same board. Measured results agree well with the simulations, showing a wide bandwidth from 22 to 32 GHz (FBW = 37%) with the gain of around 19 dBi. The beam-scanning array can realize a scanning angle of 25° over a broadband. In addition, due to the filtering features are integrated in the design, the proposed antenna could also reduce the complexity and potential cost of the frontends.

The management of volunteers – what can human resources do? A review and research agenda

Abstract: There is an increasing interest from scholars and practitioners in understanding how non-profit organizations can design and implement human resources (HR) practices to enhance desirable volunteer ...