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For the realization of an Internet of Things (IoT) with high densities of devices it is necessary that wireless communication protocols are developed that offer 1) low energy consumption; 2) simplicity of encoding and decoding; 3) an asynchronous mode of communication; and 4) an effective but simple method to deal with interference between transmissions. This paper presents the implementation, experimentation, and analysis of a protocol on the MAC sublayer that encodes information in terms of silent intervals between pulses. Based on the representation of patterns of sparse pulses, this encoding has the potential for extremely low power consumption at the transmitter side. It also results in only few conflicts between messages that are broadcast on the same band overlapped in time, while no synchronization between transmitters and receivers is necessary. The protocol is demonstrated experimentally on the 315 MHz band with 100 senders and one receiver configured in a Star topology. Theoretical analysis confirms that the probability of conflicts between messages is low, even if the number of devices increases to the order of ten thousand. This protocol facilitates the implementation of IoT devices that are restricted in terms of hardware and energy resources.

For Japanese juvenile chum salmon, mortality during coastal residency and northward migration to the Sea of Okhotsk is considered to affect their stock size. Although poor adult returns by the 2012 and 2013 brood years were widely observed along Japanese coasts, the mechanisms underlying mortality have not been defined. We collected scales from age-4 homing chum salmon captured in September–November in 2005–2017 (i.e., the 2001–2013 brood years) from three rivers in the Okhotsk and Nemuro regions, northern/eastern Hokkaido. Scale analyses revealed that growth rates during coastal residency for the 2012 and 2013 brood years of the three rivers were all significantly lower than those in other brood years. Coastal sea surface temperature (SST) in the target regions in May 2013 (i.e., the main ocean-entry timing for the 2012 brood year) was the coldest among those in 2002–2014 and was assumed to be caused by the terrestrial cold climate. Meanwhile, in May 2014, coastal SST was the second coldest and was likely influenced by offshore cold currents. These results suggest that cold coastal conditions triggered by different sources resulted in lower growth rates during coastal residency and therefore poor adult returns.

Aim: During surgery for an aortic arch aneurysm, aortic plaque in the descending aorta should be evaluated, but there are currently no suitable biomarkers for it. Surgeons should be especially aware of cerebral embolism from femoral perfusion and of peripheral embolism from stent graft deployment. Cystatin C is a known useful marker of renal dysfunction with a role as a biomarker for severity of coronary artery disease. In the absence of a suitable biomarker for aortic plaque in the descending aorta, we examine cystatin C as a candidate. Methods: In all, 75 patients who underwent surgery for an aortic arch aneurysm were enrolled. They were divided into two groups, depending on whether they had chronic kidney disease or not. The serum cystatin C value and creatinine value were evaluated preoperatively. The aortic plaque volume ratio and components in the descending aorta were calculated from preoperative enhanced computed tomography. Results: The soft plaque volume ratio was higher in patients with chronic kidney disease than in patients without it. Cystatin C positively correlated with the total aortic plaque volume ratio in all cases, and it positively correlated with the soft plaque volume ratio in both groups. Creatinine had no correlation with any type of plaque volume ratio in either group. In patients without chronic kidney disease, the soft plaque volume ratio was higher in patients with higher cystatin C levels than in patients with normal levels. Conclusion: The preoperative serum cystatin C level could be a biomarker of aortic plaque in the descending aorta in patients with an aortic arch aneurysm.

Predator–prey interactions must be considered when aiming to enhance populations by releasing artificially reared individuals into natural environments. Released individuals create an abundance of prey for predators, and a basic hypothesis of predator–prey interactions suggests that predators select large prey due to the high caloric content. An alternative hypothesis is that small individuals are vulnerable to predation due to their poor predator avoidance. This study tested these hypotheses using stocked chum (Oncorhynchus keta) and masu (Oncorhynchus masou) salmon fry and piscivorous salmonids in marine and riverine habitats in Hokkaido, Japan. Stomach contents were sampled from predators, and fork length of prey fry was measured. Then, their fork length was compared with whole stocked fry (range of mean fork length (±SD): 45.8 ± 2.55 to 49.2 ± 2.76 mm) for each habitat. As a result, prey fry were ∼3%–6% smaller than whole stocked fry, even under a prey-abundant condition (i.e., just after hatchery reared salmon fry were stocked). Piscivorous salmonids pursue schooling fry, and small fry may be easily caught due to their slow speed in avoiding predators.

We aimed to assess an impact of instantaneous wave-free ratio (iFR) on a graft failure after coronary artery bypass grafting (CABG).A total of 131 coronary arteries from 88 patients who underwent invasive coronary angiography, intracoronary pressure measurements, CABG, and scheduled follow-up coronary computed tomography angiography within one year were investigated. All studied arteries had FFR 0.80. The rate of graft failure was significantly higher in vessels with negative iFR (0.89) than in those with positive iFR (0.89) (25.7% vs. 7.3%, p = 0.012). The graft failure rates increased as the preoperative iFR values rose (iFR 0.80, 3.3%; iFR: 0.80-0.84, 5.6%; iFR: 0.85-0.89, 16.0%; iFR: 0.90-0.94, 28.0%; and iFR: 0.95-1.00, 50.0%; p = 0.002). A cut-off value of iFR to predict graft failures was determined as 0.84 by receiver-operating characteristic curve analysis with sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 88%, 62%, 25%, 97%, and 66%, respectively.The risk of graft failure becomes higher, as the preoperative iFR increases. The graft failure is significantly more frequent when a bypass graft is anastomosed on vessels with negative iFR than those with positive iFR.

Many marine species have a pelagic larval phase that undergo dispersal among habitats. Studies on marine larval dispersal have revealed a large variation in the spatial scale of dispersal, and accumulated evidence has shown that seascape patchiness is the major determinant for variation in self-recruitment. However, few studies have investigated the influence of geographic settings on marine larval dispersal. Bays or lagoons generally enhance the retention of larvae, while larvae are more likely to be flushed by strong currents in open coasts. To examine associations between larval dispersal, geographic setting, and hydrodynamics, we compared fin-scale dispersal patterns, self-recruitment, and local retention of two anemonefishes (Amphiprion frenatus and A. perideraion) between a semi-enclosed bay and an open coast in the Philippines combining genetic parentage analysis and biophysical dispersal modelling. Contrary to our expectations, parentage analysis revealed lower estimates of self-recruitment in the semi-closed bay (0–2%) than in the open coast (14–15%). The result was consistent with dispersal simulations predicting lower local retention and self-recruitment in the former (0.4% and 19%) than in the latter (2.9% and 38%). Dispersal modelling also showed that cross-shore currents toward offshore were much stronger around the semi-closed bay and were negatively correlated with local retention and self-recruitment. These results suggest that stronger cross-shore currents around the semi-closed bay transport anemonefish larvae to the offshore and mainly contributed to the lower self-recruitment. Our results highlight difficulty in predicting self-recruitment from geographic setting alone and importance of hydrodynamics on it.

Tumours or tumour-like lesions around the aortic valve are relatively rare and are difficult to diagnose. We report an interesting case of calcified thrombi in the Valsalva sinuses and coronary cusps that mimicked an aortic valve tumour. A 68-year-old man presented with a 20-mm calcified mass in the non-coronary and left-coronary cusps extending to their corresponding Valsalva sinuses, which was detected by echocardiography and contrast-enhanced computed tomography. The lesions were resected to establish the diagnosis and prevent systemic embolization. Intraoperative and histopathological examination revealed an atrophied non-coronary leaflet and calcified atherosclerotic lesions of the Valsalva sinuses and contiguous parts of the cusps, with ulceration and fibrin thrombi. The lesions were resected and aortic valve replacement was performed to avoid aortic valve dysfunction. The patient’s atrial fibrillation was controlled, and anticoagulants were discontinued 3 months postoperatively. Surgery to establish the diagnosis and to prevent systemic thromboembolism was thought to be reasonable, even in the absence of valvular dysfunction.

We examined the sea-entry conditions (i.e., timing and body size) of juvenile chum salmon that improve their survival during their coastal residency. On 25 June 2013, we sampled 365 juvenile chum salmon [57.5–98.6 mm fork length (FL)] off Konbumori, eastern Hokkaido, ⁓ 20 km east of the Kushiro River mouth, which originated from a hatchery in the Kushiro River. Sea-entry conditions of these Konbumori juveniles back-calculated using otolith daily increment analysis were compared with data from 373 juveniles released from the same hatchery that were captured at the mouth of Kushiro River (i.e., just before sea entry) from April to July 2013. Most of the Konbumori fish were estimated to have entered the sea from 25 May to 5 June, when coastal surface temperatures constantly exceeded 5 °C, which is considered favorable for juveniles. The estimated FLs at sea entry of the Konbumori fish were larger than FLs of fish sampled at the river mouth during a comparable period, which suggests that size-selective mortality existed. Back-calculated post-sea-entry growth rates of fish with larger FL at sea entry, particularly those with FL > 65 mm, tended to be high enough for survival among the Konbumori fish. Assuming growth-dependent mortality, this case study suggests that the release of larger-sized juveniles under favorable coastal temperature conditions improves their survival.

The long-distance migrations by marine fishes are difficult to track by field observation. Here, we propose a new method to track such migrations using stable nitrogen isotopic composition at the base of the food web (δ15 NBase ), which can be estimated by using compound-specific isotope analysis. δ15 NBase exclusively reflects the δ15 N of nitrate in the ocean at a regional scale and is not affected by the trophic position of sampled organisms. In other words, δ15 NBase allows for direct comparison of isotope ratios between proxy organisms of the isoscape and the target migratory animal. We initially constructed a δ15 NBase isoscape in the northern North Pacific by bulk and compound-specific isotope analyses of copepods (n = 360 and 24, respectively), and then we determined retrospective δ15 NBase values of spawning chum salmon (Oncorhynchus keta) from their vertebral centra (10 sections from each of two salmon). We then estimated the migration routes of chum salmon during their skeletal growth by using a state-space model. Our isotope tracking method successfully reproduced a known chum salmon migration route between the Okhotsk and Bering seas, and our findings suggest the presence of a new migration route to the Bering Sea Shelf during a later growth stage.

Three different techniques for stock identification, namely scale patterns, otolith thermal marks, and single-nucleotide polymorphism (SNP) markers, were applied to the same mixture samples of chum salmon collected in a setnet fishery in the Sea of Okhotsk, off Hokkaido, Japan, to evaluate consistency and accuracy among the techniques. The scale pattern and SNP analyses provided similar estimates for two regional origins (Hokkaido and Honshu) with data for 2011–2013; for each year, the Hokkaido-origin stock was dominant in September and early October, but the Honshu-origin stock was dominant by late October. The SNP analysis specified five geographical origins of chum salmon (the Okhotsk coast, Hokkaido and Honshu coasts of the Sea of Japan, and Hokkaido and Honshu coasts of the Pacific), whereas the other techniques did not identify multi-regional origins. Recaptures of otolith-marked chum salmon were used for estimating the proportions of fish originating from the Hokkaido Sea of Japan region; these estimates differed from those based on the SNP analysis. This study demonstrated that scale pattern and SNP analyses have the potential to provide nearly consistent estimates for the two regional origins, and can possibly help us to understand the interception of migrating chum salmon in Japan.