Full Shift Research Articles

An assessment of worker exposure to respirable dust and crystalline silica in workshops fabricating engineered stone.

There is a significant silicosis risk for workers fabricating engineered stone (ES) products containing crystalline silica. The aims of this study by SafeWork NSW were to: (i) assess current worker exposure to respirable dust (RD) and respirable crystalline silica (RCS) following a 5-y awareness and compliance program of inspections in ES workshops and (ii) to identify improvements in work practices from the available evidence base to further reduce exposures. One hundred and twenty-three personal full shift samples taken on as many workers and 34 static samples across 27 workshops fabricating ES were included in the final assessment. The exposure assessment was conducted using Casella Higgins-Dewell cyclones (Casella TSI) placed in the breathing zone of workers attached to SKC Air Check XR 5000 or SKC Chek TOUCH sampling pumps. Sample filters were sent to an ISO (2017) 17025:2017 accredited laboratory for gravimetric analysis for RD and X-Ray Diffraction (XRD) analysis to determine the amount of deposited RCS i.e. alpha-quartz and cristobalite. All workshops used wet methods of fabrication. The geometric mean (GM) of the pooled result for respirable dust (RD) was 0.09 mg/m3 TWA-8 h and 0.034 mg/m3 TWA-8 h for RCS. The highest exposed workers with a GM RCS of 0.062 mg/m3 TWA-8 h were those using pneumatic hand tools for cutting or grinding combined with polishing tasks. Workers operating semiautomated routers and edge polishers had the lowest GM RCS exposures of 0.022 mg/m3 TWA-8 h and 0.018 mg/m3 TWA-8 h respectively. Although ES workers remain exposed to RCS above the workplace exposure limit (WEL) of 0.05 mg/m 3 TWA-8 h, these results point to a very substantial reduction in exposures compared to poorly controlled dry methods of fabrication. Therefore, the wearing of respiratory protection by workers remains necessary until further control measures are more widely adopted across the entire industry e.g. reduction in the crystalline silica content of ES.

Accelerated weathering of silicate rock dusts predicts the slow-release liming in soils depending on rock mineralogy, soil acidity, and test methodology

The ongoing acidification of soil poses a significant threat to the proper functioning of various ecosystems worldwide. Silicate rock dusts (RD) are increasingly amended to acid soils to restore their pH, but the acid neutralising capacity (ANC) and dissolution rate of these products are highly variable and lack proper assessment protocols. It is expected that pH-dependent RD ANCs and dissolution rates dictate the pH increase in soils depending on the initial pH and pH buffer power of the soil. This study addressed these questions by comparing and validating three accelerated weathering tests for their capacity to predict the gradual liming effects in a two-year outdoor mesocosm. Five commercial RDs (two basalts, phonolite, foidite, and trachy-andesite) were tested in four acidified forest soils varying in initial pH, in texture and associated pH buffer power. First, RD dissolution was measured in aqueous batch renewal systems during one year at various starting pH (3.5, 4.5, and 5.5) and constant temperatures (20 °C, 37 °C, and 65 °C). These showed that the ANCs of RDs exhibit a fast fraction (half-life < 1 day) followed by a slower fraction. Second, titration tests of RDs at fixed solution pH, i.e., pHstat, performed between pH 3.5 and 4.5 revealed surface normalised dissolution rates that decreased factors 10–100 per unit pH increase, the slope depending on the RD’s mineralogy. Indeed, the rate ranking of observed surface area normalised dissolution rates confirmed that of literature-based values, weighed by the XRD-derived mineralogical fractions. Third, lime-calibrated agitated soil-RD suspension tests were conducted for two months, illustrating the dependency of RD ANC on soil context, and yielding ANCs that were factor 2–5 times larger than in the batch renewal test because of pH buffering effects of soil particulates. Finally, an outdoor soil mesocosm on the four acid soils amended with RDs at 12 Mg/ha and 340 Mg/ha was established and soil pH was monitored for 2 years. The observed pH trends corresponded well for both the low dose (R2a = 0.67) and the high dose (R2a = 0.93) with model predictions made using the pH- and temperature-dependent RD dissolution rates (pHstat test) and the soil pH buffer power and RD slow ANC-fraction (soil-RD suspension test). This model predicts half-lives of RD dissolution ranging between <1 month to >100 years depending on the starting pH of the soil, its pH buffer power, the RD mineralogy (XRD based) and its specific surface area. This study shows that the dissolution and ANC of RD can be most pragmatically predicted with a series of lime-calibrated soil-RD suspension tests of maximally two months.

RADio* – An Introduction to Measuring Normative Diversity in News Recommendations

In traditional recommender system literature, diversity is often seen as the opposite of similarity, and typically defined as the distance between identified topics, categories or word models. However, this is not expressive of the social science’s interpretation of diversity, which accounts for a news organization’s norms and values and which we here refer to as normative diversity. We introduce RADio, a versatile metrics framework to evaluate recommendations according to these normative goals. RADio introduces a rank-aware Jensen Shannon (JS) divergence. This combination accounts for (i) a user’s decreasing propensity to observe items further down a list and (ii) full distributional shifts as opposed to point estimates. We evaluate RADio’s ability to reflect five normative concepts in news recommendations on the Microsoft News Dataset and six (neural) recommendation algorithms, with the help of our metadata enrichment pipeline. We find that RADio provides insightful estimates that can potentially be used to inform news recommender system design.

Comparative Study on The Trademark Renewal System Between China and Anglo-countries

With the development of economy, all countries began to pay attention to the role of trademarks in economic development. Since the introduction of China's Trademark Law in 1982, the application rate of trademark registration in China has been increasing yearly, which is inseparable from the continuous improvement of China's trademark system and the continuous improvement of the awareness of trademark right holders. However, on the other hand, the renewal rate of trademark registration in China has always been low. This paper aims to compare and analyze the trademark renewal system of China and the European Union, the United Kingdom, the United States and Canada from the perspective of renewal procedure through comparative research methods, so as to put forward valuable and targeted suggestions on improving the Chinese trademark renewal system.

Socio-cultural practices and experiences of menstruation among adolescents and women of Kurichiya tribe of Wayanad: an ethnographic study

Background: Menstruation and related cultural practices are widespread in Indian communities, particularly in tribal settlements. Past studies have highlighted the negative impact of these practices on women's mental health and well-being. However, there remains a lack of comprehensive understanding regarding the specific effects of these practices on women's lives. Methods: This study utilised an urban ethnographic research design to explore cultural practices and lived experiences within urban settings. It focused on Kurichiya settlements in Wayanad's Chennalode area, part of Kalpetta municipal town in Kerala's Wayanad district. Fourteen participants, women and adolescent girls aged 15 to 50, were involved in the study. Results: The qualitative analysis identified three core themes: cultural practices of menstruation, women’s menstrual experiences, and perspectives on menstrual practices. The examination of cultural practices revealed subthemes: menarche celebration and monthly period rituals. Women's menstrual experiences encompassed emotional experiences during menarche and each monthly period. Perspectives on menstrual practices highlighted effects on mental well-being and participant’s advocacy for change. Conclusions: The study portrayed how traditional practices affect daily life for Kurichiya women, causing emotional disruption. Despite some liberalisation, a full shift in these customs remains elusive in current times.

Fatigue risk assessment of a Helicopter Emergency Medical Service crew working a 24/7 shift pattern: results of a prospective service evaluation

BackgroundThe work of Helicopter Emergency Medical Services (HEMS) teams crosses the boundaries of several high-risk occupations including medicine, aviation, and transport. Working conditions can be challenging and operational demands requires a 24-h rota, resulting in disruption of the normal circadian rhythm. HEMS crews are therefore prone to both mental and physical fatigue. As fatigue in medical providers is linked to poor cognitive performance, degradation of psychomotor skills and error, this study aimed to explore the existence of predictable patterns of crew-fatigue in a HEMS service.MethodsHEMS medical crew members working a 3-on 3-off forward rotating rota with a 5-week shift cycle were asked to do psychomotor vigilance tests (PVT) as an objective measure of fatigue. PVT testing was undertaken at the start, mid- and at the end of every shift during a full 5-week shift cycle. In addition, they were asked to score subjective tiredness with the Samn-Perelli Fatigue Scale (SPFS), and to keep a Transport Fatigue Assessment shift log, wherein they noted shift characteristics potentially related to fatigue. Primary outcome of interest was defined as the change in PVT and SPFS scores over time.ResultsMean baseline resting PVT in milliseconds at the start of the study period was 427 [390–464]. There was an overall trend towards higher PVT-scores with shift progression mean [95% CI] PVT at the start of shifts 447 [433–460]; halfway through the shift 452 [440–463]; end of the shift 459 [444–475], p = 0.10), whereas SPFS scores remained constant. Within a 5 week forward-rotating cycle, an overall trend towards a gradual increase in both average PVT (from 436 [238–454] to 460 [371–527, p = 0.68] ms;) and SPFS (from 2.9 [2.6–3.2] to 3.6 [3.1–4.0], p = 0.38) was observed, although significant interindividual variation was present. Reported SPFS scores ≥ 4 (moderate fatigue) were mainly related to workload (number of jobs) and transport mode (car-based shifts).ConclusionAn overall trend towards a decline in psychomotor vigilance and an increase in self-reported tiredness was found for HEMS crew over a 5-week shift cycle. Using a bespoke predictive fatigue tool on a day-to-day basis could increase fatigue awareness and provide a framework to which relevant mitigating options can be applied.

TOXICITY OF CHLORPYRIFOS TECHNICAL GRADE AND 20% EC TO THE FRESHWATER FISH, CHANNA PUNCTATA (BLOCH)

The toxicity studies of chlorpyrifos technical grade (TG) and 20% EC are conducted in the prevailing laboratory conditions of the fish Channa punctata in vivo to determine the median lethal concentrations i.e., LC50 values for 24, 48, 72 and 96 hrs duration by employing both static renewal and continuous flowthrough systems. The most preferred and palatable fish and mostly used pesticide the organophosphate are selected for study. The static renewal values are 6.02 µg/L, 5.82 µg/L, 5.62 µg/L, 5.38 µg/L for technical grade and for 20% EC 3.01 µg/L, 2.71 µg/L, 2.61 µg/L, and 2.51 µg/L for 24, 48, 72 and 96 hrs respectively. Similarly, for the continuous flow through system (CFTS) the values are 3.11 µg/L, 2.87 µg/L, 2.81 µg/L and 1.61 µg/L for technical grade and for 20% EC 1.91 µg/L, 1.81 µg/L, 1.61 µg/L and 1.41 µg/L respectively for 24, 48, 72 and 96 hrs. The toxicity is the concentration and duration dependent and the LC50 values in both methods decreased as well as concentrations also. The static renewal values are higher to CFTS and 20% EC is sufficiently toxic, which had synergistic effect on target and tested organism. The values are useful for data base and also in prescribing the permissible limits.

Finitely presented isomorphisms of Cuntz-Krieger algebras and continuous orbit equivalence of one-sided topological Markov shifts

We introduce the notion of finitely presented isomorphism between Cuntz–Krieger algebras, and of finitely presented isomorphic Cuntz–Krieger algebras. We prove that there exists a finitely presented isomorphism between Cuntz–Krieger algebras $\mathcal{O}_A$ and $\mathcal{O}_B$ if and only if their one-sided topological Markov shifts $(X_A,\sigma_A)$ and $(X_B,\sigma_B)$ are continuously orbit equivalent. Hence the value $\det (I-A)$ is a complete invariant for the existence of a finitely presented isomorphism between isomorphic Cuntz–Krieger algebras, so that there exists a pair of Cuntz–Krieger algebras which are isomorphic but not finitely presented isomorphic.

Conjugacy of transitive SFTs minus periodic points

AbstractIt is a question of Hochman whether any two one‐dimensional topologically mixing subshifts of finite type (SFTs) with the same entropy are topologically conjugate when their periodic points are removed. We give a negative answer, and, in fact, we prove the stronger result that there is a canonical correspondence between topological conjugacies of transitive SFTs and topological conjugacies between the systems obtained by removing the periodic points.

Distortion element in the automorphism group of a full shift

Abstract We show that there is a distortion element in a finitely generated subgroup G of the automorphism group of the full shift, namely an element of infinite order whose word norm grows polylogarithmically. As a corollary, we obtain a lower bound on the entropy dimension of any subshift containing a copy of G, and that a sofic shift’s automorphism group contains a distortion element if and only if the sofic shift is uncountable. We obtain also that groups of Turing machines and the higher-dimensional Brin–Thompson groups $mV$ admit distortion elements; in particular, $2V$ (unlike V) does not admit a proper action on a CAT $(0)$ cube complex. In each case, the distortion element roughly corresponds to the SMART machine of Cassaigne, Ollinger, and Torres-Avilés [A small minimal aperiodic reversible Turing machine. J. Comput. System Sci.84 (2017), 288–301].

Explaining Giant Apparent pK_{a} Shifts in Weak Polyelectrolyte Brushes.

Recent experiments on weak polyelectrolyte brushes found marked shifts in the effective pK_{a} that are linear in the logarithm of the salt concentration. Comparing explicit-particle simulations with mean-field calculations we show that for high grafting densities the salt concentration effect can be explained using the ideal Donnan theory, but for low grafting densities the full shift is due to a combination of the Donnan effect and the polyelectrolyte effect. The latter originates from electrostatic correlations that are neglected in the Donnan picture and that are only approximately included in the mean-field theory. Moreover, we demonstrate that the magnitude of the polyelectrolyte effect is almost invariant with respect to salt concentration but depends on the grafting density of the brush. This invariance is due to a complex cancellation of multiple effects. Based on our results, we show how the experimentally determined pK_{a} shifts may be used to infer the grafting density of brushes, a parameter that is difficult to measure directly.

Cost and statistical efficiency of posture assessment by inclinometry and observation, exemplified by paper mill work.

Postures at work are paramount in ergonomics. They can be determined using observation and inclinometry in a variety of measurement scenarios that may differ both in costs associated with collecting and processing data, and in efficiency, i.e. the precision of the eventual outcome. The trade-off between cost and efficiency has rarely been addressed in research despite the obvious interest of obtaining precise data at low costs. Median trunk and upper arm inclination were determined for full shifts in 28 paper mill workers using both observation and inclinometry. Costs were estimated using comprehensive cost equations; and efficiency, i.e. the inverted standard deviation of the group mean, was assessed on basis of exposure variance components. Cost and efficiency were estimated in simulations of six sampling scenarios: two for inclinometry (sampling from one or three shifts) and four for observation (one or three observers rating one or three shifts). Each of the six scenarios was evaluated for 1 through 50 workers. Cost-efficiency relationships between the scenarios were intricate. As an example, inclinometry was always more cost-efficient than observation for trunk inclination, except for observation strategies involving only few workers; while for arm inclination, observation by three observers of one shift per worker outperformed inclinometry on three shifts up to a budget of €20000, after which inclinometry prevailed. At a budget of €10000, the best sampling scenario for arm inclination was 2.5 times more efficient than the worst. Arm inclination could be determined with better cost-efficiency than trunk inclination. Our study illustrates that the cost-efficiency of different posture measurement strategies can be assessed and compared using easily accessible diagrams. While the numeric examples in our study are specific to the investigated occupation, exposure variables, and sampling logistics, we believe that inclinometry will, in general, outperform observation. In any specific case, we recommend a thorough analysis, using the comparison procedure proposed in the present study, of feasible strategies for obtaining data, in order to arrive at an informed decision support.

Wideband High-Efficiency Transmitarray Antenna Using Compact Double-Layer Dual-Linearly Polarized Elements

In this letter, we propose a wideband high-efficiency transmitarray antenna (TAA) consisted of compact double-layer dual-linearly polarized elements. By loading L-shaped branches and four vias, these elements achieve a low transmission loss and full phase shift in a wide frequency band. Then, an optimization method for calculating the wideband average element loss is introduced, which determines the element distribution on the transmitarray aperture. For verification, a TAA prototype consist of 400 elements is fabricated and measured. The peak gain and aperture efficiency measured at 12 GHz are 27.1 dBi and 52.5%, respectively. The measured 1-dB gain bandwidth is 20.4% and the minimum aperture efficiency achieved across the 1-dB gain bandwidth is 33%. The results reveal that the proposed TAA exhibits the advantages of flat gain bandwidth, high aperture efficiency, low profile, and low cost, endowing it with the potential for conformal applications and the capability to reliably connect satellite links as a communication antenna.

Three-dimensional Underground Facility Automatic Renewal System Construction to Updated Integrated Underground Spatial Map

Three-dimensional Underground Facility Automatic Renewal System Construction to Updated Integrated Underground Spatial Map

Corrigendum to “Uniformly continuous orbit equivalence of Markov shifts and gauge actions on Cuntz–Krieger algebras”

In the given proofs of Theorem 1.5 in the author’s article "K. Matsumoto, Uniformly continuous orbit equivalence of Markov shifts and gauge actions on Cuntz–Krieger algebras", Proc. Amer. Math. Soc. 145 (2017), pp. 1131–1140, there are two places that the matrices are needed to be primitive. The statement of Theorem 1.5 and its proof are corrected.

A double-layer Huygens’ metasurface with complete phase coverage and its dual-polarized meta-lens antenna application

A novel double-layer Huygens’ unit with dual-polarized response and complete phase coverage has been proposed for highly efficient meta-lens antenna application. The designed unit is a symmetric structure in which the double-layer metallic patterns not only act as the electric dipoles but also induce the magnetic dipoles. The balance between the initial electric dipole and the induced magnetic dipole makes the impedance of the metasurface match with that of free space, thus allowing efficient transmission of electromagnetic waves. Moreover, full transmission phase shift and near-unit transmission amplitude can be achieved simultaneously by change the structural parameters of the unit. Utilizing such electromagnetic properties, a dual-polarized meta-lens consisting of 35 × 35 units with size of 161 × 161 mm2 is designed, fabricated and measured. The results exhibit its good radiation performance. The maximum gain at a frequency of 28 GHz reaches 30.8 dBi, with an aperture efficiency of 42.3%. The 3-dB gain bandwidth reaches 12.5%, covering the frequency range of 26.7–30.2 GHz. The simple structure of the designed dual-polarized metasurface, high gain and high antenna efficiency make it an important antenna engineering role.

Decidability of flow equivalence and isomorphism problems for graph C*-algebras and quiver representations

We note that the deep results of Grunewald and Segal on algorithmic problems for arithmetic groups imply the decidability of several matrix equivalence problems involving poset-blocked matrices over Z (the integers). Consequently, results of Eilers, Restorff, Ruiz and Sørensen imply that isomorphism and stable isomorphism of unital graph C*-algebras (including the Cuntz-Krieger algebras) are decidable. One can also decide flow equivalence for shifts of finite type and isomorphism of Z-quiver representations (i.e., finite diagrams of homomorphisms of finitely generated abelian groups).

Lyapunov irregular set of Banach cocycles

Let be a topologically mixing subshift of finite type and let be a Hölder continuous map where is the set of invertible elements of a Banach ring B. We prove that either all ergodic measures have the same maximal Lyapunov exponent, or the irregular set is residual in and has full upper capacity topological entropy of . We also prove for generic fiber-bunched cocycles, similar statements can be strengthened by considering the Bowen topological entropy.

Manipulation of reflected acoustic wavefront by a comb-like metasurface

This work proposes a design strategy for an acoustic metasurface with the goal of flexibly modulating reflected waveforms. The metasurface unit is composed of a rigid base and a column of rectangular partitions arranged in a comb-like configuration. A full 2π phase shift of the reflected waves can be achieved by adjusting the height of these rectangular partitions. The utilization of a particle swarm optimization algorithm determines the specific phase shift of the units along the metasurface. As a pragmatic example, it is shown that the comb-like metasurface offers a superior ability to direct the propagation of reflected sound waves in the desired directions, and experiments are performed to verify this anomalous reflection phenomenon. Furthermore, numerical calculations effectively demonstrate the application of the acoustic ground illusion. This work presents an effective and feasible design scheme for acoustic wave manipulation.

Automorphism groups of random substitution subshifts

We prove that for a suitably nice class of random substitutions, their corresponding subshifts have automorphism groups that contain an infinite simple subgroup and a copy of the automorphism group of a full shift. Hence, they are countable, non-amenable and non-residually finite. To show this, we introduce the concept of shuffles and generalised shuffles for random substitutions, as well as a local version of recognisability for random substitutions that will be of independent interest. Without recognisability, we need a more refined notion of recognisable words in order to understand their automorphisms. We show that the existence of a single recognisable word is often enough to embed the automorphism group of a full shift in the automorphism group of the random substitution subshift.