on 24-Oct-2020 (Sat)

if, over your lifetime, you will spend more than 5 minutes looking something up or will lose more than 5 minutes as a result of not knowing something, then it’s worthwhile to memorize it with spaced repetition.

don’t use spaced repetition if you need it sooner than 5 days or it’s worth less than 5 minutes

The musician and comedian Martin Mull has observed that “writing about music is like dancing about architecture”.

This takes advantage of a fundamental fact about human memory: as we are repeatedly tested on a question, our memory of the answer gets stronger, and we are likely to retain it for longer The literature on this effect is vast. A useful entrée is: Gwern Branwen, Spaced Repetition for Efficient Learning. .

This is the big, counterintuitive advantage of spaced repetition: you get exponential returns for increased effort.

The more transformative the tool, the larger the gap that is opened.

Definicja 1.1 (iloczyn skalarny). (Standardowym) iloczynem skalarnym w R n nazy- wamy funkcję R n × R n 3 (x, y) 7−→ hx, yi := n X i=1 x i y i ∈ R . Jak wiadomo z wykładów Algebry Liniowej, iloczyn skalarny jest dwuliniowy (liniowy względem każdej zmiennej z osobna), symetryczny (tzn. hx , yi = hy, xi dla wszystkich

Natomiast dowolny ruch chaotyczny, np. ruchy Browna, czy wszelkie postacie ruchu postępowego są przykładami ruchu nie będącego ruchem drgającym.

istnieje położenie równowagi trwałej (tzn. istnieje minimum energii potencjalnej, a więc istnieje siła zwrotna przywracająca stan równowagi), 2. układ ma bezwładność (dla układów mechanicznych jest to masa), 3. układ nie traci energii (nie ma żadnych sił oporu)

dx Ud k =

Dyspnea is a common and often debilitating symptom that affects up to 50% of patients admitted to acute, tertiary care hospitals and a quarter of patients seeking care in ambulatory settings.

Specific physiological processes may be linked to corresponding sensory descriptors, the best characterized of which are sensations of work or effort, tightness, and air hunger/unsatisfied inspiration

TABLE 3.

DESCRIPTORS FOR AIR HUNGER COMMONLY CHOSEN FROM LISTS

Urge to breathe (115)	Unsatisfied inspiration (83)
Like breath hold (115)	Feeling of suffocation (115)
Starved for air (115)	Need for more air (37)
Hunger for air (115)	Breath does not go in all the way (37)
Breaths felt too small (115)	Cannot get enough air (58)

evidence has emerged that dyspnea is a predictor of hospitalization (13) and mortality in patients with chronic lung disease (14), and in some cases is more closely correlated with 5-year survival than forced expiratory volume in 1 second (FEV₁) (15). Dyspnea is also more closely associated with cardiac mortality than angina (16).

We define dyspnea as “a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity,”

(1) distinct mechanisms and afferent pathways are reliably associated with different sensory qualities (notably work/effort, tightness, and air hunger/unsatisfied inspiration), (2) distinct sensations most often do not occur in isolation, and (3) dyspnea sensations also vary in their unpleasantness and in their emotional and behavioral significance

Perception entails conscious recognition and interpretation of sensory stimuli and their meaning. Therefore, as is the case with pain, adequate assessment of dyspnea depends on self-report

Distinctive sensory qualities are important in considering the physiological mechanisms underlying the breathing discomfort, but the definition of dyspnea should be neutral with respect to any particular quality

There is evidence that different physiological derangements lead to qualitatively different sensations (27, 29–32), and attention to these qualities may be helpful in the evaluation of the cause and treatment of the patient's discomfort

With encouraging support from family, friends, and health care providers, symptoms may not seem so bad, and disabilities may be overcome or ameliorated

In addition to traditionally defined sensory afferents, information on the state of respiration is available from respiratory motor areas of the brain, which can send an ascending copy of their descending motor activity to perceptual areas (corollary discharge)

Perceptions of work and effort probably arise through some combination of respiratory muscle afferents and perceived cortical motor command or corollary discharge (50). Similar mechanisms give rise to sensations of work and effort from exercising limb muscles (reviewed in References 42 and 51)

As long as sensations of increased work or effort in breathing and the achieved ventilation are consistent with expected responses to exercise, they are not necessarily unpleasant (52, 53), and may not even be the primary reason for stopping

“Tightness” is commonly experienced during bronchoconstriction (27, 65–69). Some studies suggest that chest tightness is the dominant experience in the early stages of an asthma attack, but as airway narrowing worsens, patients also report work/effort and air hunger/unsatisfied inspiration (65, 68).

There is also evidence in patients with asthma that perception of increased work/effort does not respond as rapidly as tightness to treatment with nebulized albuterol (67), suggesting that work/effort may be more related to increased respiratory motor output needed to overcome airflow obstruction (e.g., due to inflammation), whereas tightness may be more specifically related to stimulation of airway receptors. Together, these findings suggest that tightness arises from pulmonary afferents rather than being a work-related sensation

A perception of not getting enough (or of needing more) air, which has been variously labeled as air hunger, unsatisfied inspiration, or an unpleasant urge to breathe, can be induced experimentally by increasing inspiratory drive (e.g., with exercise, hypercapnia, or hypoxia), especially if the capacity to satisfy the increased ventilatory demand is limited.

[Air hunger]

Similar sensations have been reported during symptom-limited exercise testing by patients with restrictive (32) or obstructive (31, 32, 65) lung disease (in particular, when dynamic hyperinflation restricts inspiratory capacity among the latter)

Air hunger/unsatisfied inspiration is intensified by stimuli that increase spontaneous ventilatory drive (84, 89, 90), such as hypoxia, hypercapnia, acidosis, and signals arising from exercise-related drive (91, 92), especially if ventilatory response is constrained (52, 53).

In contrast, increased voluntary motor drive to respiratory muscles, which originates in the cerebral cortex (95, 96), predominantly evokes a perception of respiratory effort (58, 61), which, in healthy volunteers, is not as unpleasant as air hunger (97).

Mechanoreceptors in the lungs, airways, and chest wall provide afferent information about achieved pulmonary ventilation and can inhibit (relieve) air hunger/unsatisfied inspiration (98–103)

Unsatisfied inspiration or air hunger is not specific to any particular disease or stimulus

A consistent finding across experimental exercise and clinical studies is that patients with a variety of conditions (or normal subjects with chest wall corseting) report greater difficulty and discomfort during inspiration compared with expiration (inspiratory difficulty)

This suggests that, in susceptible individuals, air hunger may occur even in the absence of reduced ventilatory capacity. Factors such as excessive ventilatory drive or impaired perception of achieved ventilation may play a role. There also may be a role for increased sensitivity to CO₂ (which may, in turn, have a component of genetic predisposition) or excessive response to cerebral alkalosis or hypoxia due to hyperventilation-induced hypocapnia (118, 124)

A core pattern has emerged: dyspnea activates cortico-limbic structures (134–143) that also subserve interoceptive awareness of homeostatic threats such as thirst and hunger (144–148) or pain (134, 137–140, 149–152)

There is good evidence that opioid drugs reduce dyspnea (see E valuation and T reatment ). Laboratory studies in healthy subjects show that opioids reduce the discomfort of air hunger (166) but not the discomfort of work or effort (167).

Opioids likely act both by depressing spontaneous respiratory drive (thus reducing corollary discharge), and by modulating cortical activity, as they do in pain

In addition to laboratory, radiographic, and clinical studies, the words or phrases patients use to describe the quality of the breathing discomfort ( Table 3 ) may provide insight into the underlying pathophysiological mechanisms (27, 29–32, 36).

Chest tightness may be relatively specific for dyspnea due to bronchoconstriction ( 30, 67, 68, 74, 132). Sensations of “air hunger” and “inability to get a deep breath,” which probably represent the combined effects of increased drive to breathe and limited tidal volume, are commonly seen in association with dynamic hyperinflation (31, 86) and other conditions characterized by restrictive mechanics (e.g., heart failure or pulmonary fibrosis). Sensations of effort, suffocation, and rapid breathing have been found to characterize CO₂-induced panic attacks in patients diagnosed with panic disorder (119), but are nonspecific (200)

Although supplemental oxygen improves mortality in chronically hypoxemic patients with COPD, there are conflicting data about its ability to relieve breathlessness (220–224)

Oxygen therapy may be useful for patients with advanced heart or lung disease, in particular those who are hypoxemic at rest or with minimal activity (204, 212, 213, 224, 230)

“The term mindful learning is used here in a very specific way, drawn from the concept of mindfulness that I defined in an earlier book by that name. A mindful approach to any activity has three characteristics: the continuous creation of new categories; openness to new information; and an implicit awareness of more than one perspective. Mindlessness, in contrast, is characterized by an entrapment in old categories; by automatic behavior that precludes attending to new signals; and by action that operates from a single perspective. Being mindless, colloquially speaking, is like being on autopilot. In Mindfulness, I described the benefits of a mindful approach for our psychological and physical well-being. For instance, elderly adults given mindfulness treatments were shown to live longer than their peers who were not given such treatments. In this book I use the concept of mindfulness as a lens through which to explore its importance in the world I know best, teaching and learning.”

THE SEVEN PERVASIVE MYTHS “Certain myths and fairy tales help advance a culture by passing on a profound and complex wisdom to succeeding generations. Others, however, deserve to be questioned. This book is about seven pervasive myths, or mindsets, that undermine the process of learning and how we can avoid their debilitating effects in a wide variety of settings. 1. The basics must be learned so well that they become second nature. 2. Paying attention means staying focused on one thing at a time. 3. Delaying gratification is important. 4. Rote memorization is necessary in education. 5. Forgetting is a problem. 6. Intelligence is knowing ‘what’s out there.’ 7. There are right and wrong answers.”

For instance, elderly adults given mindfulness treatments were shown to live longer than their peers who were not given such treatments. In this book I use the concept of mindfulness as a lens through which to explore its importance in the world I know best, teaching and learning.”