Re: Difficulty
Gifford Brickley
difficulty_1_target can be different for various ways to measure difficulty.Traditionally, it represents a hash where the leading 32 bits are zero and the rest are one (this is known as "pool difficulty" or "pdiff").The Bitcoin protocol represents targets as a custom floating point type with limited precision; as a result, Bitcoin clients often approximate difficulty based on this (this is known as "bdiff").
Here's a fast way to calculate bitcoin difficulty. It uses a modified Taylor series for the logarithm (you can see tutorials on flipcode and wikipedia) and relies on logs to transform the difficulty calculation:
Here's an even faster way to compute the difficulty, using std::ldexp(). This particular function lets you scale by a power of two almost for free, by directly adjusting the exponent on the floating point number. Thus, the difficulty calculation gets reduced to a couple integer arithmetic steps, single floating point divide, and a single scale-by-power-of-2.
The difficulty is adjusted every 2016 blocks based on the time it took to find the previous 2016 blocks. At the desired rate of one block each 10 minutes, 2016 blocks would take exactly two weeks to find. If the previous 2016 blocks took more than two weeks to find, the difficulty is reduced. If they took less than two weeks, the difficulty is increased. The change in difficulty is in proportion to the amount of time over or under two weeks the previous 2016 blocks took to find.
The difficulty is set such that the previous 2016 blocks would have been found at the rate of one every 10 minutes, so we were calculating (D * 2**48 / 0xffff) hashes in 600 seconds. That means the hash rate of the network was
The higher the hash rate, the more difficult it is for a fraudster to gain control of the blockchain since more hashing power is needed. In other words, the higher the difficulty, the more secure the network.
The interactive effect of exercise intensity and task difficulty on human cognitive processing was investigated using the P3 component of an event-related brain potential (ERP). Exercise intensity was established using Borg's rating of perceived exertion (RPE) scale, and task difficulty was manipulated using a modified flanker task comprised of incongruent and neutral trials. Twelve participants (22 to 30 y) performed the flanker task during a baseline session, and again after light (RPE: 11), moderate (RPE: 13), and hard (RPE: 15) cycling exercise. Results indicated that the P3 amplitude increases across task conditions following light and moderate cycling, but not during hard cycling, relative to baseline, suggesting that P3 amplitude may change in an inverted U fashion by as a result of acute exercise intensity. Additionally, the expected delay in P3 latency for incongruent relative to neutral trials was observed during the baseline condition. However, following acute exercise these task condition differences diminished across exercise intensities. Moreover, reaction times following all exercise conditions were shorter when compared to the baseline condition. These findings suggest that P3 latency is more sensitive to task difficulty manipulated by a flanker task than behavioral measures, and P3 latency during trials requiring greater executive control processes might be more sensitive to the effects of acute exercise than tasks requiring minimal effort.
Measurements: The Short Physical Performance Battery (SPPB), gait speed, Berg Balance Scale (BBS), grip strength, and Timed Up and Go Test (TUG) were evaluated at baseline. Seven ADL items were assessed at baseline and 6, 12, and 18 months. The onset of ADL disability was self-report of difficulty in any of the seven ADL items. Logistic regression models were fitted for each of the physical performance measures to predict onset of ADL difficulty at 6, 12, and 18 months.
Results: After controlling for age, comorbid conditions, and sex, the BBS was the most consistent and best predictor for the onset of ADL difficulty over an 18-month period (6 months, c-statistic=0.725, (95% confidence interval (CI)=0.60-0.85; 12 months, c-statistic=0.840 95% CI=0.75, 0.93; 18 months, c-statistic=0.821, 95% CI=0.71, 0.93). The SPPB showed excellent predictive value for the onset of difficulty at 12 months. Ninety-five, 89, and 75 older adults completed the 6, 12, and 18-month follow-up visits, respectively.
Conclusion: BBS, followed by SPPB, TUG, gait speed, and grip strength, were predictive of the onset of ADL difficulty over an 18-month period in community-dwelling older adults. Screening nondisabled older adults with simple performance tests could allow clinicians to identify those at risk for ADL difficulty and may help to detect early functional decline.
Robert Enders, can you see how those complaints might be easiest to dismiss from the lowest difficulty setting? And how it might seem as though the complainers are likely to lose when actually those who are losing because the game is rigged are those who are most likely to have something to complain about?
That leaves us with societal action, which usually means government intervention. Mechanisms include progressive taxes, guaranteed access to the necessities of life, quality education, customs and laws that prevent discrimination and profiling, protections and guarantees for those on other difficulty settings, etc.
For those who are asking now what. We know we are playing on easy, but what do you want us to do about it? James King brought something up earlier. Each of us is an NPC in the lives of everyone around us, and as such we actually SET the difficulty level of the game for everyone else. You want to make a difference then start examining your own life and behavior for ways that you treat Straight White Men differently from everyone else, and try resetting your defaults. The problem is that it is harder then you might think because the bias is so deeply ingrained in our culture that many people apply it completely unintentionally. Overt sexism/racism, etc. is relatively easy to fight, both in other people and in yourself. It is much more subtle stuff that really does the damage. Like this blog post about how women are not crazy, society just sets out to make us think we are. -message-to-women-from-a-man-you-are-not-%E2%80%9Ccrazy%E2%80%9D/. That is just one example (that came quickly to both mind and google), but it is the kind of thing that gets under the skin and really adds up over time. So you are playing on easy and you really want to make a difference, just remember that you are on of the characters handing out experience to other players, you can ignore their difficulty setting if you want to.
Funny story: know a dude, SWM, liberal, graduated from college and professional school, married a fellow professional, felt properly guilty about his SWM privilege (lowest difficulty settings) and set out to make up for that guilt and make the playing field more fair for everyone. In the process he gave up, voluntarily, a more lucrative career and time he would have preferred investing in a family to work for political and economic equality for women. Became a towering beacon of straight white male sensitivity for the entire community. Marched, voted, organized, agitated, used his Whiteness and Maleness for good, all the while being a devoted husband and respected (as well as a SWM can be) member of his fairly liberal community. He wanted to start a family, but his wife persuaded him to wait until they had better established themselves and struck a blow for justice before they settled down. He reluctantly agreed, but he agreed. And he put everything he had into it.
Many of my friends and family who did not have the SWM difficulty switch set for them are still stuck in the same (or nearly the same) situation into which they were born. In fact, most of the people I went to elementary school with (my family were the white minority in school) are either dead, strung out, or still living in the same conditions they were born to.
1. Based on your point of view, the difficulty setting of life is most impacted not by gender, race and sexual orientation, but simply by the country and circumstances into which an individual is born. For example, it is quite conceivable that a gay black female born in the USA would have an easier setting than a straight white male born in a rural area of Russia. Now, if birth country is always the same, then absolutely the straight white male has the easiest time of it.
Occasional difficulty swallowing, such as when you eat too fast or don't chew your food well enough, usually isn't cause for concern. But ongoing dysphagia can be a serious medical condition that needs treatment.
Although swallowing difficulties can't be prevented, you can reduce your risk of occasional difficulty swallowing by eating slowly and chewing your food well. However, if you have symptoms of dysphagia, see a healthcare professional.
Swallowing difficulty is the inability to swallow foods or liquids with ease. People who have a hard time swallowing may choke on their food or liquid when trying to swallow. Dysphagia is the medical name for difficulty swallowing.
According to the National Institute on Deafness and Other Communication Disorders (NIDCD), there are 50 pairs of muscles and nerves used to help you swallow. In other words, there are lots of things that can go wrong and lead to problems swallowing. Some conditions related to difficulty swallowing include:
The Montana Department of Public Health and Human Services summarizes which foods to eat and which to avoid if you have swallowing difficulty. Here are some of its recommendations for foods to avoid or use only when carefully prepared:
The POST-DISCHARGE COPING DIFFICULTY SCALE (PDCDS) is a patient self-report tool measuring difficulty with coping at home following discharge from the hospital. This is a unidimensional scale that is administered by phone typically between two and three weeks post-discharge.
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