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Konon Avdeev
Konon Avdeev


There is general consensus that projected warming will cause earlier snowmelt, but how snowmelt rates will respond to climate change is poorly known. We present snowpack observations from western North America illustrating that shallower snowpack melts earlier, and at lower rates, than deeper, later-lying snow-cover. The observations provide the context for a hypothesis of slower snowmelt in a warmer world. We test this hypothesis using climate model simulations for both a control time period and re-run with a future climate scenario, and find that the fraction of meltwater volume produced at high snowmelt rates is greatly reduced in a warmer climate. The reduction is caused by a contraction of the snowmelt season to a time of lower available energy, reducing by as much as 64% the snow-covered area exposed to energy sufficient to drive high snowmelt rates. These results have unresolved implications on soil moisture deficits, vegetation stress, and streamflow declines.


When a hurricane strikes land, the destruction of property and the environment and the loss of life are largely confined to a narrow coastal area. This is because hurricanes are fuelled by moisture from the ocean1,2,3, and so hurricane intensity decays rapidly after striking land4,5. In contrast to the effect of a warming climate on hurricane intensification, many aspects of which are fairly well understood6,7,8,9,10, little is known of its effect on hurricane decay. Here we analyse intensity data for North Atlantic landfalling hurricanes11 over the past 50 years and show that hurricane decay has slowed, and that the slowdown in the decay over time is in direct proportion to a contemporaneous rise in the sea surface temperature12. Thus, whereas in the late 1960s a typical hurricane lost about 75 per cent of its intensity in the first day past landfall, now the corresponding decay is only about 50 per cent. We also show, using computational simulations, that warmer sea surface temperatures induce a slower decay by increasing the stock of moisture that a hurricane carries as it hits land. This stored moisture constitutes a source of heat that is not considered in theoretical models of decay13,14,15. Additionally, we show that climate-modulated changes in hurricane tracks16,17 contribute to the increasingly slow decay. Our findings suggest that as the world continues to warm, the destructive power of hurricanes will extend progressively farther inland.

The destructive economic impact of the Covid-19 pandemic was distributed unequally across the population. Gender, race and ethnicity, age, education level, and a worker's industry and occupation all mattered. We analyze the initial negative effect and the lingering effect through the recovery phase across demographic and socio-economic groups. The initial negative impact on employment was larger for women, minorities, the less educated, and the young, even after accounting for the industries and occupations they worked in. By November 2020, however, the differential impact between men and women, and between education and age groups has vanished. Across race and ethnic groups, Hispanics and Asians were the worse hit but made up for most of the lost ground, while the initial impact on Blacks was smaller but recovery slower.

In fact, it might seem that for the vast majority of Go code, making it generic will imply making it slower. But before we start sinking into a deep pit of despair, let us run some benchmarks, look at some assembly and verify some behaviors.

How bad is this extra dereference in practice? Intuitively, we can assume that calling methods on an object in a generic function will always be slower than in a non-generic function that simply takes an interface as an argument, because Generics will devolve what previously were pointer calls into a twice-indirect interface call, ostensibily slower than a plain interface call.

The results are not surprising. The function that has been specialized to take a *strings.Builder directly is the fastest, because it allowed the compiler to inline the WriteByte calls inside of it. The generic function is measurably slower than the simplest possible implementation taking an io.ByteWriter interface as an argument. We can see that the impact of the extra load from the generic dictionary is not significant, because both the itab and the Generics dictionary will be very warm in cache in this micro-benchmark (however, do keep reading for an analysis of how cache contention affects Generic code).

"It's exciting that our study shows making specific diet choices may lead to a slower rate of cognitive decline," said study author Thomas M. Holland, MD, MS of Rush University Medical Center in Chicago. "Something as simple as eating more fruits and vegetables and drinking more tea is an easy way for people to take an active role in maintaining their brain health."

People who had the highest intake of kaempferol had a 0.4 units per decade slower rate of cognitive decline compared to those in the lowest group. Those with the highest intake of quercetin had a 0.2 units per decade slower rate of cognitive decline compared to those in the lowest group. And people with the highest intake of myricetin had a 0.3 units per decade slower rate of cognitive decline compared to those in the lowest group. Dietary isorhamnetin was not tied to global cognition.

Holland noted that the study shows an association between higher amounts of dietary flavonols and slower cognitive decline but does not prove that flavonols directly cause a slower rate of cognitive decline.

Big questions, however, remain. Will the labor market continue to loosen on its own without much of an increase in unemployment? How quickly will wage growth slow? And, how much will slower wage growth translate into slower price growth? Given the magnitude of the issues, it is unlikely that we will see inflation much below 3.5 percent in 2023.

In the study, consumption of green leafy vegetables was positively and significantly associated with slower cognitive decline. When comparing the highest daily consumption (median 1.3 servings a day) with the lowest (median 0.09 servings a day), the rate of cognitive decline among those who consumed the most to those who consumed the least was equivalent to being 11 years younger cognitively, based on average global cognitive scores over time. There was no evidence that the association was affected by cardiovascular conditions, depressive symptoms, low weight, or obesity.

The researchers also examined the relationship between cognitive change and nutrients for which green leafy vegetables are a rich source (folate, phylloquinone, nitrate, α-tocopherol, kaempferol, and lutein). Intake of these nutrients were each individually positively and significantly associated with slower rates of cognitive decline and were not due to other underlying health issues. Further investigation indicated that phylloquinone, lutein and folate likely were the source of the effect seen on cognitive decline.

Many slow creatures inhabit the animal world. In Slow and Slower students will have the opportunity to read about some of these sluggish animals. Students can compare the slow animals to the slower ones using the full-page chart. As they read this interesting and informative book, students will have the opportunity to ask and answer questions as well as to classify information. Supportive photographs, detailed maps and charts, high-frequency words, and repetitive phrases support readers.

A Zeeman slower is a scientific apparatus that is commonly used in atomic physics to slow and cool a beam of hot atoms to speeds of several meters per second and temperatures below a kelvin. The Gas-phase atoms used in atomic physics are often generated in an oven by heating a solid or liquid atomic sample to temperatures where the vapor pressure is high enough that there are a substantial number of atoms in the gas phase. These atoms effuse out of a hole in the oven with average speeds on the order of hundreds of m/s and large velocity distributions (due to their high temperature). The Zeeman slower is attached close to where the hot atoms exit the oven and is used to slow them to less than 10 m/s (slowing) with a very small velocity spread (cooling).

A Zeeman slower consists of a cylinder, through which an atomic beam travels, a pump laser that counterpropagates with respect to the beam's direction , and a magnetic field (commonly produced by a solenoid-like coil) that points along the cylinder's axis with a spatially varying magnitude. The pump laser, which is required to be near-resonant with atomic transition, Doppler slows a certain velocity class within the velocity distribution of the beam. The spatially varying magnetic field is designed to Zeeman shift the resonant frequency to match the decreasing Doppler shift as the atoms are slowed to lower velocities while they propagate through the Zeeman slower allowing pump laser to be continuously resonant and provide a slowing force.

There is nevertheless a problem in this basic scheme because of the Doppler effect. The resonance of the atom is rather narrow (on the order of a few megaHertz), and after having decreased its momentum by a few recoil momenta, it is no longer in resonance with the pump beam because in its frame, the frequency of the laser has shifted. The Zeeman slower[4] uses the fact that a magnetic field can change the resonance frequency of an atom using the Zeeman effect to tackle this problem.

The most common approach is to require that we have a magnetic field profile that varies in the z \displaystyle z direction such that the atoms experience a constant acceleration a = η a max \displaystyle a=\eta a_\textmax as they fly along the axis of the slower. It has been recently shown however, that a different approach yields better results.[5]

The Zeeman slower is usually used as a preliminary step to cool the atoms in order to trap them in a magneto-optical trap. Thus it aims at a final velocity of about 10 m/s (depending on the atom used), starting with a beam of atoms with a velocity of a few hundred meters per second. The final speed to be reached is a compromise between the technical difficulty of having a long Zeeman slower and the maximal speed allowed for an efficient loading into the trap. 041b061a72


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