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Topic Review
North African Climate Cycles
North African climate cycles have a unique history that can be traced back millions of years. The cyclic climate pattern of the Sahara is characterized by significant shifts in the strength of the North African Monsoon. When the North African Monsoon is at its strongest, annual precipitation and consequently vegetation in the Sahara region increase, resulting in conditions commonly referred to as the "green Sahara". For a relatively weak North African Monsoon, the opposite is true, with decreased annual precipitation and less vegetation resulting in a phase of the Sahara climate cycle known as the "desert Sahara". Variations in the climate of the Sahara region can, at the simplest level, be attributed to the changes in insolation because of slow shifts in Earth's orbital parameters. The parameters include the precession of the equinoxes, obliquity, and eccentricity as put forth by the Milankovitch theory. The precession of the equinoxes is regarded as the most important orbital parameter in the formation of the "green Sahara" and "desert Sahara" cycle. A January 2019 MIT paper in Science Advances shows a cycle from wet to dry approximately every 20,000 years.
  • 599
  • 11 Nov 2022
Topic Review
Northern Cheyenne Indian Reservation
The Northern Cheyenne Tribe of the Northern Cheyenne Indian Reservation (Template:Lang-chy; formerly named the Tongue River) is the federally recognized Northern Cheyenne tribe. Located in southeastern Montana, the reservation is approximately 690 square miles (1,800 km2) in size and home to approximately 5,000 Cheyenne people. The tribal and government headquarters are located in Lame Deer, also the home of the annual Northern Cheyenne pow wow. The reservation is bounded on the east by the Tongue River and on the west by the Crow Reservation. There are small parcels of non-contiguous off-reservation trust lands in Meade County, South Dakota, northeast of the city of Sturgis. Its timbered ridges that extend into northwestern South Dakota are part of Custer National Forest and it is approximately 40 miles (64 km) east of the site of the 1876 Battle of the Little Bighorn. According to tribal enrollment figures as of March 2013, there were approximately 10,050 enrolled tribal members, of which about 4,939 were residing on the reservation,Template:Full short with approximately 91% of the population Native American (full or part blood quantum) and 72.8% identifying as Cheyenne. Slightly more than a quarter of the population five years or older spoke a language other than English. Members of the Crow Nation also live on the reservation.
  • 496
  • 23 Nov 2022
Topic Review
Northwestern European People
Northwestern European people are a pan-ethnic group, or multi-ethnic regional grouping, and the inhabitants of Northwestern Europe. Northwest or Northwestern Europeans can usually trace back full or partial heritage to Great Britain and Ireland, Northern Germany, Denmark , Sweden, Norway , the Netherlands, Northern France, Belgium, and other places connected to Northwestern Europe geographically or culturally. As the pan-ethnic group is also a cultural category, rather than exclusively geographical; it often can include peoples with ancestry from bordering regions such as Austria, Finland , Southern Germany, and Switzerland . There is a large Northwestern European diaspora, with significant numbers within North America (Northwestern European Americans and Northwestern European Canadians), and Northwestern European Australians in Oceania. Other subgroupings of Europeans include Eastern European people and Southern European people.
  • 21.2K
  • 28 Oct 2022
Topic Review
Nostocyclopeptides
Nostocyclopeptides (Ncps) are a small class of bioactive nonribosomal peptides thus far identified only in cyanobacteria of the genus Nostoc. They are composed of six-seven amino acid residues and contain a unique imino linkage formed between C-terminal aldehyde and an N-terminal amine group of the conserved tyrosine. Nostocyclopeptides occur both in cyclic and linear form.
  • 462
  • 05 Nov 2021
Topic Review
NOx Emission Reduction and Recovery
Since its first confirmed case at the end of 2019, COVID-19 has become a global pandemic in three months with more than 1.4 million confirmed cases worldwide, as of early April 2020. Quantifying the changes of pollutant emissions due to COVID-19 and associated governmental control measures is crucial to understand its impacts on economy, air pollution, and society. We used the WRF-GC model and the tropospheric NO2 column observations retrieved by the TROPOMI instrument to derive the top-down NOx emission change estimation between the three periods: P1 (January 1st to January 22nd, 2020), P2 (January 23rd, Wuhan lockdown, to February 9th, 2020), and P3 (February 10th, back-to-work day, to March 12th, 2020). We found that NOx emissions in East China averaged during P2 decreased by 50% compared to those averaged during P1. The NOx emissions averaged during P3 increased by 26% compared to those during P2. Most provinces in East China gradually regained some of their NOx emissions after February 10, the official back-to-work day, but NOx emissions in most provinces have not yet to return to their previous levels in early January. NOx emissions in Wuhan, the first epicenter of COVID-19, had no sign of emission recovering by March 12. A few provinces, such as Zhejiang and Shanxi, have recovered fast, with their averaged NOx emissions during P3 almost back to pre-lockdown levels.
  • 1.2K
  • 29 Oct 2020
Topic Review
Numerical Simulation Methods in Shale Oil Flow
The pore structure of shale oil reservoirs is complex, and the microscale and nanoscale effect is obvious in the development of shale oil reservoirs. Understanding the oil flow mechanism in shale reservoirs is essential for optimizing the development plan and enhancing the recovery rate of shale oil reservoirs.
  • 346
  • 10 May 2023
Topic Review
Nutriepigenomics in Environmental-Associated Oxidative Stress
Complex molecular mechanisms define our responses to environmental stimuli. Beyond the DNA sequence itself, epigenetic machinery orchestrates changes in gene expression induced by diet, physical activity, stress and pollution, among others. Importantly, nutrition has a strong impact on epigenetic players and, consequently, sustains a promising role in the regulation of cellular responses such as oxidative stress. As oxidative stress is a natural physiological process where the presence of reactive oxygen-derived species and nitrogen-derived species overcomes the uptake strategy of antioxidant defenses, it plays an essential role in epigenetic changes induced by environmental pollutants and culminates in signaling the disruption of redox control. 
  • 622
  • 18 Apr 2023
Topic Review
Object Detection for Small Water Floater
Object detection is one of the most widely used applications in UAV missions. Detection of small objects in unmanned aerial vehicle (UAV) images remains a persistent challenge due to the limited pixel values and interference from background noise.
  • 330
  • 07 Aug 2023
Topic Review
Occurrence of Triclosan in the Water Environment
Triclosan (TCS), a kind of pharmaceuticals and personal care products (PPCPs), is widely used and has had a large production over years. It is an emerging pollutant in the water environment that has attracted global attention due to its toxic effects on organisms and aquatic ecosystems, and its concentrations in the water environment are expected to increase since the COVID-19 pandemic outbreak.
  • 806
  • 09 Sep 2022
Topic Review
Occurrences of Endotoxin in Agriculture
Agricultural operations and the processing sector generate dust laden with endotoxin in the workplace. Endotoxin, a pro-inflammatory agent, has adverse effects on health, especially in the lungs, as exposure to endotoxin reduces lung function capacity. Endotoxin exposure to workers and its harmful impact on the health of agricultural workers needs to be studied in detail for future interventions to reduce exposure to endotoxin.
  • 556
  • 27 Dec 2022
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