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Objective: The purpose of this study was to investigate the rat skin penetration abilities of two commercially available low-level laser therapy (LLLT) devices during 150 sec of irradiation. Background data: Effective LLLT irradiation typically lasts from 20 sec up to a few minutes, but the LLLT time-profiles for skin penetration of light energy have not yet been investigated. Materials and methods: Sixty-two skin flaps overlaying rat's gastrocnemius muscles were harvested and immediately irradiated with LLLT devices. Irradiation was performed either with a 810 nm, 200 mW continuous wave laser, or with a 904 nm, 60 mW superpulsed laser, and the amount of penetrating light energy was measured by an optical power meter and registered at seven time points (range, 1-150 sec). Results: With the continuous wave 810 nm laser probe in skin contact, the amount of penetrating light energy was stable at *20% (SEM -0.6) of the initial optical output during 150 sec irradiation. However, irradiation with the superpulsed 904 nm, 60 mW laser showed a linear increase in penetrating energy from 38% (SEM -1.4) to 58% (SEM -3.5) during 150 sec of exposure. The skin penetration abilities were significantly different ( p < 0.01) between the two lasers at all measured time points. Conclusions: LLLT irradiation through rat skin leaves sufficient subdermal light energy to influence pathological processes and tissue repair. The finding that superpulsed 904 nm LLLT light energy penetrates 2-3 easier through the rat skin barrier than 810 nm continuous wave LLLT, corresponds well with results of LLLT dose analyses in systematic reviews of LLLT in musculoskeletal disorders. This may explain why the differentiation between these laser types has been needed in the clinical dosage recommendations of World Association for Laser Therapy.

A number of factors are associated with the development of childhood asthma. The purpose of this study was to establish the prevalence of childhood asthma and to explore the socioeconomic background factors associated with childhood asthma in a Norwegian cohort of children aged 4-5 yrs.A questionnaire was given to parents in connection with the ordinary child control of 4-5-yr-old children in Vestfold county, Norway. In addition to the question "Has the child at present or ever had asthma?", a number of medical and socioeconomical background factors were registered.Of the 2,430 parents, 1,913 (79%) responded. Of the 163 (cumulative prevalence 8.7%) children with confirmed asthma, 19 did not use any medication and were regarded as having outgrown their asthma. Several background factors were significantly associated with asthma in a logistic regression analysis: few rooms at home, psychosocial problems, fever more than three times during the last year, hay fever, reaction to food and mother or father with chronic disease.The findings indicate that socioeconomic background factors are associated with asthma in childhood, in addition to other known risk factors.

Robustness and bounded latency are among the key requirements in wireless industrial networks. A typical traffic patterns is convergecast, where sensors sends data towards a sink, resulting in a funneling effect with increased traffic intensity. This letter proposes the Layered autonomous Time Slotted Channel Hopping (TSCH) scheduler for convergecast traffic, which addresses the funneling effect while reducing the band occupancy. It divides the slotframe into layers where all nodes have one timeslot reserved for forwarding its own traffic. Layers are organized to allow spatially reuse such that traffic belonging to a node may be forwarded at multiple hops simultaneously. This is achieved autonomously by exploiting a node's knowledge of the routing topology. We evaluate the Layered scheduler through theoretical analysis and simulations in Cooja. Results show that Layered attains bounded latency even when nodes are utilizing all their available resources. This is achieved with significantly reduced band occupancy compared to Escalator, an autonomous scheduler for convergecast traffic. The performance is traded‐off by increased maximum latency.

Concepts such as Industry 4.0 and Cyber-Physical Systems may bring forward a new industrial revolution. These concepts require extensive connectivity far beyond what is provided by traditional industrial networks. The Industrial Internet of Things (IIoT) bridges this gap by employing wireless connectivity and IP networking. In order for wireless networks to meet the strict requirements of the industrial domain, the Time Slotted Channel Hopping (TSCH) MAC is often employed. The properties of a TSCH network are defined by the schedule, which dictates transmission opportunities for all nodes. We survey the literature for these schedulers, describe and organize them according to their operation: Centralized, Collaborative, Autonomous, Hybrid, and Static. For each category and the field as a whole, we provide a holistic view and describe historical trends, highlight key developments, and identify trends, such as the attention towards autonomous mechanisms. Each of the 76 schedulers is analyzed into their common components to allow for comparison between schedulers and a deeper understanding of functionality and key properties. This reveals trends such as increasing complexity and the utilization of centralized principles in several collaborative schedulers. Further, each scheduler is evaluated qualitatively to identify its objectives. Altogether this allows us to point out challenges in existing work and identify areas for future research, including fault tolerance, scalability, non-convergecast traffic patterns, and hybrid scheduling strategies.

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