Functional differences in seasonally absorbed nitrogen in a winter-green perennial herb.

Nitrogen (N) uptake in response to its availability and effective N-use are important for determining plant fitness, as N is a major limiting resource and its availability changes both seasonally and annually. Storage organs such as bulbs are considered an adaptive trait with respect to plant N-use strategies. It is well known that N is remobilized from storage organs to satisfy the high demand for new growth that is not completely satisfied by external uptake alone. However, little is known about how this N absorbed during different seasons contributes to plant performance. By manipulating seasonal N availability in potted Lycoris radiata var. radiata (Amaryllidaceae), a winter-green perennial, we found that the N absorbed during different seasons had different effects on leaf growth and leaf N concentrations, effectively increasing the growth and survival of the plants. N absorbed during the summer (leafless period; N was thus stored in the bulb) enhanced plant growth by increasing leaf growth. Compared with the plants supplied with N during autumn (leaf flush period), the leafy plants also showed greater growth per unit leaf area despite the lower area-based photosynthetic capacity of the latter. By contrast, N absorbed during the autumn increased the leaf N concentration and thus the photosynthetic capacity, which was considered to enhance survival and growth of the plant during winter by reducing the potentially fatal risk caused by the absorption of photons under low temperature. Our findings have important implications for estimating plant responses to environmental changes. We predict that changes in seasonal N availability impact the performance of plants, even that of perennials that have large storage organs, via an altered relative investment of N into different functions.

Atrial and Ventricular Arrhythmia-Associated Factors in Stable Patients with Chronic Obstructive Pulmonary Disease.

BACKGROUND: Supraventricular and ventricular premature complexes (SVPC and VPC, respectively) are associated with chronic obstructive pulmonary disease (COPD) and with increased mortality in COPD patients. However, there are few reports on the causes of arrhythmia in COPD patients. OBJECTIVES: This study explores the associations between cardiopulmonary dysfunction and COPD by comparing patients with defined arrhythmias (>100 beats per 24 h) and those without, based on 24-hour electrocardiogram (ECG) recordings. METHODS: Patients with arrhythmia underwent a 24-hour ECG and subsequent pulmonary function tests, computed tomography, ECG, 6-min walk test (6MWT), and BODE (body mass index, airflow obstruction, modified Medical Research Council Dyspnoea Scale, exercise capacity) index calculation. RESULTS: Of 103 study patients (71 COPD patients and 32 at-risk patients), 36 had VPC, 45 had SVPC, 20 had both, and 42 had neither. The predicted post-bronchodilator forced expiratory volume in 1 s, the proportion of low-attenuation area on computed tomography, and BODE index values were significantly worse in the SVPC and VPC groups compared with the corresponding reference groups. Patients in the VPC group showed significantly increased right ventricular pressure and increased desaturation in the 6MWT compared with the reference group. In the multivariate analyses, bronchodilator use was a significant risk factor in the SVPC group, whereas in the VPC group, all parameters of the BODE index except for the dyspnoea score were identified as risk factors. CONCLUSIONS: Increased SVPC might be caused by bronchodilator use, whereas increased VPC is likely related to the peculiar pathophysiology of COPD.

Effects of receptive listening on the congruence of speakers' response latencies in dialogues.

The present study investigated the receptiveness of speakers toward conversational partners in dialogues by comparing duration of response latencies in both Compromise and Debate conditions. 12 dyads of speakers holding opposing opinions participated in a 15-min. dialogue. Six dyads in the Compromise condition reached a conclusion through discussion and consideration of the partner's opinion. The six dyads in the Debate condition imposed their opinion on the conversational partner. Analysis indicated that in compromise dialogues, the response latencies of the conversational partners become similar over the time course, while in debate diaogues, the response latency does not become similar, suggesting that speakers having a receptive attitude adjust their response latencies to match the partner's. The role of congruence of response latencies in dyadic communication was discussed.