Seismic interferometry has now been applied to the exploration of the Earth's interior at scales ranging from local to global. Most studies have used surface‐wave propagation. Recently, some studies ...have focused on body wave propagation on local and regional scales but not on a global scale. In this study, we succeed in extracting global body wave propagation(of P, PP, PKP, S, SS, ScS, P′P′, etc. waves) using seismic hum with frequency‐wave number filtering in the range of 5 to 40 mHz. Although the observed body wave propagation is similar to that of the corresponding components of Green's functions, there are two differences between them: the lack of reflection phases in the observation and the dominance of shear‐coupled PL waves in the observation. These differences originate from the dominance of shear‐traction sources on the Earth's surface, which causes the breakdown of equipartition among modes with different radial orders. For further studies of body wave exploration by seismic interferometry, these differences should be considered.
Key Points
We succeed in extracting global body-wave propagation using seismic hum.
SPL waves in the observation are more dominant than those in Green's functions.
The dominance originates from their shear‐traction sources on the seafloor.
Ocean swell activities excite body‐wave microseisms that contain information on the Earth's internal structure. Although seismic interferometry is feasible for exploring structures, it faces the ...problem of spurious phases stemming from an inhomogeneous source distribution. This paper proposes a new method for inferring seismic discontinuity structures beneath receivers using body‐wave microseisms. This method considers the excitation sources of body‐wave microseisms to be spatially localized and persistent over time. To detect the P‐s conversion beneath the receivers, we generalize the receiver function analysis for earthquakes to body‐wave microseisms. The resultant receiver functions are migrated to the depth section. The detected 410‐ and 660‐km mantle discontinuities are consistent with the results obtained using earthquakes, thereby demonstrating the feasibility of our method for exploring deep‐earth interiors. This study is a significant step toward body‐wave exploration considering the sources of P‐wave microseisms to be isolated events.
Plain Language Summary
The ocean waves excite persistent and random ground motions called microseisms. Since this excitation is independent of seismic activities, this wavefield has information about seismic structures that earthquakes never have. For the deep structure, such as the mantle and core, body‐wave microseisms are more suitable than surface‐wave microseisms because body‐wave microseisms have better sensitivity. Previous studies using body‐wave microseisms mainly adopted the cross‐correlation analysis known as seismic interferometry. This method assumes that the microseisms are excited everywhere. However, the inhomogeneous source distribution of body‐wave microseisms causes artifacts for exploration by seismic interferometry. We developed a new method which circumvents this problem. Assuming that the body‐wave microseisms are spatially isolated, this method extracted the P‐s converted waves beneath receivers from body‐wave microseisms. The 3‐Dimensional imaging result of extracted P‐s converted waves shows both 410‐ and 660‐km mantle discontinuities, consistent with results using earthquakes. This study shows the potential of body‐wave microseisms for exploring the deep earth structure.
Key Points
The P‐S waves at mantle discontinuities were extracted from the ambient noise excited by the ocean swells
We developed the source deconvolution method to generalize a receiver function method to P‐wave microseisms
The migration result of P‐S waves was consistent with previous studies, showing the potential of P‐wave microseisms to seismic structures
Background
This study aimed to examine the effects of Lactobacillus casei strain Shirota (LcS) on gut–brain interactions under stressful conditions.
Methods
Three double‐blind, placebo‐controlled ...trials were conducted to examine the effects of LcS on psychological and physiological stress responses in healthy medical students under academic examination stress. Subjects received LcS‐fermented milk or placebo daily for 8 weeks prior to taking a national standardized examination. Subjective anxiety scores, salivary cortisol levels, and the presence of physical symptoms during the intervention were pooled and analyzed. In the animal study, rats were given feed with or without LcS for 2 weeks, then submitted to water avoidance stress (WAS). Plasma corticosterone concentration and the expression of cFos and corticotropin releasing factor (CRF) in the paraventricular nucleus (PVN) were measured immediately after WAS. In an electrophysiological study, gastric vagal afferent nerve activity was monitored after intragastric administration of LcS to urethane‐anesthetized rats.
Key Results
Academic stress‐induced increases in salivary cortisol levels and the incidence rate of physical symptoms were significantly suppressed in the LcS group compared with the placebo group. In rats pretreated with LcS, WAS‐induced increases in plasma corticosterone were significantly suppressed, and the number of CRF‐expressing cells in the PVN was reduced. Intragastric administration of LcS stimulated gastric vagal afferent activity in a dose‐dependent manner.
Conclusions & Inferences
These findings suggest that LcS may prevent hypersecretion of cortisol and physical symptoms under stressful conditions, possibly through vagal afferent signaling to the brain and reduced stress reactivity in the PVN.
We examined the effects of the probiotic Lactobacillus casei strain Shirota (LcS) on stress markers and stress‐related symptoms in healthy medical students preparing for a major examination, and found that salivary cortisol levels and physical complaints which increased toward the exam day were significantly suppressed by LcS treatment. Results of animal studies suggested that the ingestion of LcS suppresses stress‐induced increases in glucocorticoids, possibly through vagal afferent signaling from the upper intestines to the brain and reduced stress reactivity in the hypothalamus.
Kernel-type density or regression estimator does not produce a constant estimator variance over the domain. To correct this problem, K. Nishida and Y. Kanazawa (2011, 2015) proposed a ...variance-stabilizing (VS) local variable bandwidth for kernel regression estimators. K. Nishida (2017) proposed another strategy to construct VS local linear regression estimator using a convex combination of three skewing estimators proposed by Choi and Hall (1998). In this study, we show that variance stabilization can be accomplished by a Bayesian approach in the case of kernel density estimator using conjugate prior.
Aims
To confirm the stress‐relieving effects of heat‐inactivated, enteric‐colonizing Lactobacillus gasseri CP2305 (paraprobiotic CP2305) in medical students taking a cadaver dissection course.
...Methods and Results
Healthy students (21 males and 11 females) took paraprobiotic CP2305 daily for 5 weeks during a cadaver dissection course. The General Health Questionnaire and the Pittsburgh Sleep Quality Index were employed to assess stress‐related somatic symptoms and sleep quality respectively. The aggravation of stress‐associated somatic symptoms was observed in female students (P = 0·029). Sleep quality was improved in the paraprobiotic CP2305 group (P = 0·038), particularly in men (P = 0·004). Among men, paraprobiotic CP2305 shortened sleep latency (P = 0·035) and increased sleep duration (P = 0·048). Diarrhoea‐like symptoms were also effectively controlled with CP2305 (P = 0·005) in men. Thus, we observed sex‐related differences in the effects of paraprobiotic CP2305. In addition, CP2305 affected the growth of faecal Bacteroides vulgatus and Dorea longicatena, which are involved in intestinal inflammation.
Conclusions
CP2305 is a potential paraprobiotic that regulates stress responses, and its beneficial effects may depend on specific cell component(s).
Significance and Impact of the Study
This study characterizes the effects of a stress‐relieving para‐psychobiotic in humans.
The role of autophagy in the heart Nishida, K; Kyoi, S; Yamaguchi, O ...
Cell death and differentiation,
01/2009, Letnik:
16, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Autophagy has evolved as a conserving process that uses bulk degradation and recycling of cytoplasmic components, such as long-lived proteins and organelles. In the heart, autophagy is important for ...the turnover of organelles at low basal levels under normal conditions and it is upregulated in response to stresses such as ischemia/reperfusion and in cardiovascular diseases such as heart failure. Cardiac remodeling involves increased rates of cardiomyocyte cell death and precedes heart failure. The simultaneously occurring multiple features of failing hearts include not only apoptosis and necrosis but also autophagy as well. However, it has been unclear as to whether autophagy is a sign of failed cardiomyocyte repair or is a suicide pathway for failing cardiomyocytes. The functional role of autophagy during ischemia/reperfusion in the heart is complex. It has also been unclear whether autophagy is protective or detrimental in response to ischemia/reperfusion in the heart. In this review, we will summarize the role of autophagy in the heart under both normal conditions and in response to stress.
This pilot study investigated the effects of the probiotic Lactobacillus casei strain Shirota (LcS) on psychological, physiological, and physical stress responses in medical students undertaking an ...authorised nationwide examination for promotion. In a double-blind, placebo-controlled trial, 24 and 23 healthy medical students consumed a fermented milk containing LcS and a placebo milk, respectively, once a day for 8 weeks until the day before the examination. Psychophysical state, salivary cortisol, faecal serotonin, and plasma L-tryptophan were analysed on 5 different sampling days (8 weeks before, 2 weeks before, 1 day before, immediately after, and 2 weeks after the examination). Physical symptoms were also recorded in a diary by subjects during the intervention period for 8 weeks. In association with a significant elevation of anxiety at 1 day before the examination, salivary cortisol and plasma L-tryptophan levels were significantly increased in only the placebo group (P<0.05). Two weeks after the examination, the LcS group had significantly higher faecal serotonin levels (P<0.05) than the placebo group. Moreover, the rate of subjects experiencing common abdominal and cold symptoms and total number of days experiencing these physical symptoms per subject were significantly lower in the LcS group than in the placebo group during the pre-examination period at 5-6 weeks (each P<0.05) and 7-8 weeks (each P<0.01) during the intervention period. Our results suggest that the daily consumption of fermented milk containing LcS may exert beneficial effects preventing the onset of physical symptoms in healthy subjects exposed to stressful situations.
Abstract
A novel dropping nitrification–cotton-based denitrification reactor was developed for total nitrogen (N) removal from ammonium (NH4+)-contaminated groundwater. The nitrogen removal ability ...of the reactor was evaluated for 91 days. A 1 m-long dropping nitrification unit was fed with synthetic groundwater containing 30 mg-NH4+-N/L at a flow rate of 2.16 L/d. The outlet of the dropping nitrification unit was connected to the cotton-based denitrification unit. The NH4+ present in the groundwater was completely oxidized (>90% nitrification efficiency) by nitrifying bacteria to nitrite (NO2–) and nitrate (NO3–) in the dropping nitrification unit. Subsequently, the generated NO2– and NO3– were denitrified (96%–98% denitrification efficiency) by denitrifying bacteria in the cotton-based denitrification unit under anoxic conditions. Organic carbons released from the cotton presumably acted as electron donors for heterotrophic denitrification. Nitrifying and denitrifying bacteria were colonized in higher abundance in the dropping nitrification and cotton-based denitrification units, respectively. The total N removal rate and efficiency of the dropping nitrification–cotton-based denitrification reactor for 91 days were 58.1–66.9 mg-N/d and 96%–98%, respectively. Therefore, the dropping nitrification–cotton-based denitrification reactor will be an efficient, sustainable, and promising option for total N removal from NH4+-contaminated groundwater.
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