scholarly journals Diurnal and Weekly Cycles in IPv6 Traffic

Author(s):  
Stephen D. Strowes
Keyword(s):  
2016 ◽  
Vol 43 (16) ◽  
pp. 8760-8768 ◽  
Author(s):  
Xin Yang ◽  
Zhanqing Li ◽  
Lin Liu ◽  
Lijing Zhou ◽  
Maureen Cribb ◽  
...  
Keyword(s):  

2021 ◽  
Author(s):  
Mark Wenig ◽  
Sheng Ye ◽  
Ying Zhu ◽  
Hanlin Zhang

<p>The problem of elevated NO<sub>2</sub> levels in cities has gained some attention in the public in recent years and has given rise to questions about the plausibility of banning diesel engines in cities, the meaning of exceedances of air quality limits and the effects of corona lock-downs on air quality to name a few. Urban air quality is typically monitored using a relatively small number of monitoring stations. Those in-situ measurements follow certain guidelines in terms of inlet height and location relative to streets, but the question remains how a limited number of point measurements can capture the spatial variability in cities. In this talk we present two measurement campaigns in Hong Kong and Munich where we utilized a combination of mobile in-situ and stationary remote sensing differential optical absorption spectroscopy (DOAS) instruments. We developed an algorithm to separate spatial and temporal patterns in order to generate pollution maps that represent average NO<sub>2</sub> exposure. </p> <p>We use those maps to identify pollution hot spots and capture the weekly cycles of on-road NO2 levels and spatial dependency of long-term changes and we analyze how on-road measurements compare to monitoring station data and how the measurement height and distance to traffic emissions have to be considered when interpreting observed concentration patterns.</p>


2016 ◽  
Author(s):  
Iolanda Ialongo ◽  
Jay Herman ◽  
Nick Krotkov ◽  
Lok Lamsal ◽  
Folkert Boersma ◽  
...  

Abstract. We present the comparison of satellite-based OMI (Ozone Monitoring Instrument) NO2 products with ground-based observations in Helsinki. OMI NO2 total columns, available from standard product (SP) and DOMINO algorithm, are compared with the measurements performed by the Pandora spectrometer in Helsinki in 2012. The relative difference between Pandora #21 and OMI SP retrievals is 4 % and −6 % for clear sky and all sky conditions, respectively. DOMINO NO2 retrievals showed slightly lower total columns with median differences about −5 % and −14 % for clear sky and all sky conditions, respectively. Large differences often correspond to cloudy autumn-winter days with solar zenith angles above 65°. Nevertheless, the differences remain within the retrieval uncertainties. Furthermore, the weekly and seasonal cycles from OMI, Pandora and NO2 surface concentrations are compared. Both satellite- and ground-based data show a similar weekly cycle, with lower NO2 levels during the weekend compared to the weekdays as result of reduced emissions from traffic and industrial activities. Also the seasonal cycle shows a similar behaviour, even though the results are affected by the fact that most of the data are available during spring-summer because of cloud cover in other seasons. This is one of few works in which OMI NO2 retrievals are evaluated in a urban site at high latitudes (60° N). Despite the city of Helsinki having relatively small pollution sources, OMI retrievals have proved to be able to describe air quality features and variability similar to surface observations. This adds confidence in using satellite observations for air quality monitoring also at high latitudes.


2021 ◽  
Author(s):  
Stephen Dery ◽  
Tricia Stadnyk ◽  
Tara Troy ◽  
Marco Hernandez-Henriquez

<p>Sub-daily and weekly streamflow cycles termed hydropeaking are common features in regulated rivers across the globe. Weekly periodicity in flows arises from fluctuating hydropower demand and production tied to socioeconomic activity, typically with higher consumption during weekdays followed by reductions on weekends. In this presentation, we will introduce a novel weekly hydropeaking index to quantify the intensity and prevalence of weekly hydropeaking cycles at 368 sites across the United States of America (USA) and Canada over 1920-2019. Our results reveal a robust weekly hydropeaking signal exists at 1.3% of available sites starting in 1920 with a fraction that peaks at 16.7% of sites in 1963. Highly hydropeaking signals then diminish to only 3.3% of available sites in 2019, marking a 21st century declining pattern in hydropeaking intensity across parts of North America. Application of the Mann-Kendall Test reveals 95 locally significant declines in weekly hydropeaking intensity between 1980-2019. Our results can be attributed to diminishing differences between streamflow on weekends versus weekdays in regulated rivers across Canada and the USA. We will conclude the presentation with a discussion on how these findings may be tied to shifts in socioeconomic activity, alternative modes of electricity production, and legislative and policy changes impacting water management in regulated systems.</p>


1945 ◽  
Vol 91 (382) ◽  
pp. 79-88 ◽  
Author(s):  
R. Klein ◽  
R. F. Nunn

The unfailing regularity of the rhythm of his manic-depressive cycles each week renders the patient in question particularly suitable for investigation, and throws into relief changes which might be less marked if the transition between the phases was more gradual and the periodicity less certain.


Author(s):  
Christian Braun ◽  
Cornelia Gnägi ◽  
Jolanta Klukowska-Rötzler ◽  
Sufian Ahmad ◽  
Meret Ricklin ◽  
...  

2019 ◽  
Vol 56 (5) ◽  
pp. 1331-1337
Author(s):  
Fabián Correa-Morales ◽  
Felipe Dzul-Manzanilla ◽  
Wilbert Bibiano-Marín ◽  
José Vadillo-Sánchez ◽  
Anuar Medina-Barreiro ◽  
...  

Abstract A cluster-randomized controlled trial quantified the entomological efficacy of aerial ultra-low volume (AULV) applications of the insecticide chlorpyrifos against Aedes aegypti in Puerto Vallarta, México, during November–October 2017. The trial involved 16 large (1 × 1 km) clusters distributed between treatment-control arms. Primary endpoint was the abundance of Ae. aegypti indoors (total adults, females, and blood-fed females) collected using Prokopack aspirators. After four consecutive weekly cycles of AULV, all adult Ae. aegypti infestation indices were significantly lower in the treatment arm (OR and IRR ≤ 0.28). Efficacy in reducing indoor Ae. aegypti increased with each weekly application cycle from 30 to 73% (total adults), 33 to 76% (females), and 45.5 to 89% (blood-fed females). Entomological indices remained significantly lower in the treatment arm up to 2 wk after the fourth spraying round. Performing AULV spraying can have significant and lasting entomological impact on Ae. aegypti as long as multiple (ideally four) spray cycles are implemented using an effective insecticide.


2016 ◽  
Vol 16 (11) ◽  
pp. 6863-6881 ◽  
Author(s):  
Olga Lyapina ◽  
Martin G. Schultz ◽  
Andreas Hense

Abstract. The high density of European surface ozone monitoring sites provides unique opportunities for the investigation of regional ozone representativeness and for the evaluation of chemistry climate models. The regional representativeness of European ozone measurements is examined through a cluster analysis (CA) of 4 years of 3-hourly ozone data from 1492 European surface monitoring stations in the Airbase database; the time resolution corresponds to the output frequency of the model that is compared to the data in this study. K-means clustering is implemented for seasonal–diurnal variations (i) in absolute mixing ratio units and (ii) normalized by the overall mean ozone mixing ratio at each site. Statistical tests suggest that each CA can distinguish between four and five different ozone pollution regimes. The individual clusters reveal differences in seasonal–diurnal cycles, showing typical patterns of the ozone behavior for more polluted stations or more rural background. The robustness of the clustering was tested with a series of k-means runs decreasing randomly the size of the initial data set or lengths of the time series. Except for the Po Valley, the clustering does not provide a regional differentiation, as the member stations within each cluster are generally distributed all over Europe. The typical seasonal, diurnal, and weekly cycles of each cluster are compared to the output of the multi-year global reanalysis produced within the Monitoring of Atmospheric Composition and Climate (MACC) project. While the MACC reanalysis generally captures the shape of the diurnal cycles and the diurnal amplitudes, it is not able to reproduce the seasonal cycles very well and it exhibits a high bias up to 12 nmol mol−1. The bias decreases from more polluted clusters to cleaner ones. Also, the seasonal and weekly cycles and frequency distributions of ozone mixing ratios are better described for clusters with relatively clean signatures. Due to relative sparsity of CO and NOx measurements these were not included in the CA. However, simulated CO and NOx mixing ratios are consistent with the general classification into more polluted and more background sites. Mean CO mixing ratios are within 140–145 nmol mol−1 (CL1–CL3) and 130–135 nmol mol−1 (CL4 and CL5), and NOx mixing ratios are within 4–6 nmol mol−1 and 2–3 nmol mol−1, respectively. These results confirm that relatively coarse-scale global models are more suitable for simulation of regional background concentrations, which are less variable in space and time. We conclude that CA of surface ozone observations provides a powerful and robust way to stratify sets of stations, being thus more suitable for model evaluation.


2012 ◽  
Vol 12 (13) ◽  
pp. 5755-5771 ◽  
Author(s):  
A. Sanchez-Lorenzo ◽  
P. Laux ◽  
H.-J. Hendricks Franssen ◽  
J. Calbó ◽  
S. Vogl ◽  
...  

Abstract. Several studies have claimed to have found significant weekly cycles of meteorological variables appearing over large domains, which can hardly be related to urban effects exclusively. Nevertheless, there is still an ongoing scientific debate whether these large-scale weekly cycles exist or not, and some other studies fail to reproduce them with statistical significance. In addition to the lack of the positive proof for the existence of these cycles, their possible physical explanations have been controversially discussed during the last years. In this work we review the main results about this topic published during the recent two decades, including a summary of the existence or non-existence of significant weekly weather cycles across different regions of the world, mainly over the US, Europe and Asia. In addition, some shortcomings of common statistical methods for analyzing weekly cycles are listed. Finally, a brief summary of supposed causes of the weekly cycles, focusing on the aerosol-cloud-radiation interactions and their impact on meteorological variables as a result of the weekly cycles of anthropogenic activities, and possible directions for future research, is presented.


Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4800-4800
Author(s):  
Maria N. Dimopoulou ◽  
Christina Kalpadakis ◽  
Evangelia M. Dimitriadou ◽  
Marie-Christine Kyrtsonis ◽  
Styliani I. Kokoris ◽  
...  

Abstract Splenectomy has traditionally been considered as standard treatment for SMZL conferring a survival advantage over chemotherapy. However it carries significant complications, especially in elderly patients. The purpose of the present study is to evaluate the safety and efficacy of Rituximab for the treatment of SMZL. Fourteen patients with SMZL, diagnosed in our Department were treated with Rituximab. Diagnosis was established using standard criteria. Twelve received Rituximab as first line treatment at a median time of 2 months (1–120) after diagnosis. The remaining two received Rituximab after splenectomy. Four patients were symptomatic. Patients’ median age was 68 yrs (range 50–78) and four were male. All non-splenectomized patients had palpable splenomegaly before treatment. The median size of the spleen was 10 cm blcm (3–20 cm). 12/14 patients had anemia, 6/14 leukocytosis, 9/14 lymphocytosis, 4/14 leukopenia and 5/14 thrombocytopenia prior to treatment initiation. Rituximab was administered for six weekly cycles of 375mg/m2. 6/13 patients received maintenance treatment, starting at a median time of four months (range 2–7) after the completion of the six cycles. Maintenance was given as 375mg/m2 every two months. Complete clinical response was defined as disappearance of palpable splenomegaly. Complete hematologic response was defined as the restoration of all hematologic parameters to normal values and partial hematologic response as an improvement of abnormal values without complete normalization. Molecular remission was defined as PCR negativity for IgH rearrangement in patients with negative bone marrow biopsy. 11 of 11 non-splenectomized patients achieved a complete clinical response (the 12th patient is still under treatment and response cannot be evaluated). Symptomatic patients had resolution of disease/splenomegaly related symptoms. 8/13 (62%) patients achieved a complete hematologic response, including the two previously splenectomized patients and 5/13 (38%) a partial hematologic response. Anemia was resolved in 8/11 patients, leukocytosis in 6/6, leukopenia in 1/3 and thrombocytopenia in 4/4 patients. Bone marrow biopsy after treatment disclosed persistent but reduced infiltration in 6/10, disappearance of lymphomatous infiltration in 3/10 and remained unchanged in a single patient. 2/3 patients with negative bone marrow biopsy were in molecular remission, while one patient remained PCR positive after treatment. He subsequently received a second course of four weekly cycles and became PCR negative. No patient presented infectious complications after Rituximab administration. Infusion related side effects were easily treated with steroids, antihistamines and paracetamol. Two patients, who did not receive maintenance treatment progressed with reappearance of splenomegaly both at 7 months after completion of treatment and were retreated with six cycles of Rituximab. One of them had a second response and the other remained with stable disease. All patients are alive. Median follow up after treatment initiation is 16 months (range 1–22) and median response duration has not been reached. In conclusion, Rituximab is a safe and effective treatment for SMZL and can be considered an alternative to splenectomy as first line therapy. Maintenance may be important for consolidation of response.


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