on 28-Apr-2021 (Wed)

Many of Oxman's projects use new platforms and techniques for 3D printing and fabrication.

Many of Oxman's

сделал петли голубого цвета на краю од ного покрывала, где оно соединяется с другим; так же сделал он и на краю по следнего покрывала, для соединения его с другим;

Acute cough exists for less than three weeks and is most commonly due to an acute respiratory tract infection. Other considerations include an acute exacerbation of underlying chronic pulmonary disease, pneumonia, and pulmonary embolism.

Patients who seek medical attention for chronic cough are more likely to be female [3-5]. Among patients with chronic cough, women tend to cough more often and to have heightened cough reflex sensitivity compared to men [4].

Each cough occurs through the stimulation of a complex reflex arc. This is initiated by the irritation of cough receptors that exist not only in the epithelium of the upper and lower respiratory tracts, but also in the pericardium, esophagus, diaphragm, and stomach.

The most common etiologies of chronic cough are upper airway cough syndrome (due to postnasal drip), asthma, and gastroesophageal reflux [1-3,15-20]. However, a number of other important etiologies must also be considered in patients presenting with persistent cough.

One study showed that in nearly half of patients, subacute cough was post infectious and resolved without specific therapy [21].

Other less common causes of chronic cough include a number of disorders affecting the airways (nonasthmatic eosinophilic bronchitis, chronic bronchitis, bronchiectasis, neoplasm, foreign body) or the pulmonary parenchyma (interstitial lung disease, lung abscess) (table 1). A cause is identified in 75 to 90 percent of patients with chronic cough [2,15,17]. However, some patients may experience chronic cough of unclear etiology for years, despite extensive evaluation. The etiology of so-called "chronic idiopathic cough" is unknown; exaggerated cough reflex sensitivity has been suggested [5,22].

Symptoms of postnasal drip include frequent nasal discharge, a sensation of liquid dripping into the back of the throat, and frequent throat clearing [2]. However, postnasal drip may also be "silent," so that the absence of these symptoms does not necessarily exclude the diagnosis [17]. Clues on physical examination are a cobblestone appearance to the nasopharyngeal mucosa and the presence of secretions in the nasopharynx.

Asthma is the second leading cause of persistent cough in adults, and the most common cause in children [25]. Cough due to asthma is commonly accompanied by episodic wheezing and dyspnea; however, it can also be the sole manifestation of a form of asthma called "cough variant asthma" [26-28]. Cough variant asthma can progress to include wheezing and dyspnea [29]

A diagnosis of asthma is suggested when the patient is atopic or has a family history of asthma. Asthma-related cough may be seasonal, may follow an upper respiratory tract infection, or may worsen upon exposure to cold, dry air, dust, mold, or to certain fumes or fragrances. A cough accompanied by wheezing or dyspnea, or one that occurs following initiation of beta-blocker therapy also suggests asthma.

Patients with active asthma typically have eosinophilic bronchitis. The diagnosis of nonasthmatic eosinophilic bronchitis should be considered in atopic patients with an idiopathic chronic cough and sputum eosinophilia in the absence of airway hyperreactivity.

Thus, the best way to confirm asthma as a cause of cough is to demonstrate improvement in the cough with appropriate therapy for asthma (eg, two to four weeks of inhaled glucocorticoids [31]).

Gastroesophageal reflux is often reported to be the second or third most common cause of persistent cough [1,2,15,17], although it is the most common cause in some reports, occurring in 30 to 40 percent of patients [18,35]. Many patients complain of symptoms of gastroesophageal reflux (heartburn or a sour taste in the mouth); however, these symptoms are absent in more than 40 percent of patients in whom cough is due to reflux [2,15,36,37].

Gastroesophageal reflux can also contribute to asthma symptoms

Laryngopharyngeal reflux (LPR) is the retrograde movement of gastric contents (acid and enzymes such as pepsin) into the laryngopharynx leading to symptoms referable to the larynx/hypopharynx [46]. Most patients are relatively unaware of LPR with only 35 percent reporting heartburn. Typical LPR symptoms include dysphonia/hoarseness, chronic cough, mild dysphagia and nonproductive throat clearing.

LPR is seen as primarily an upper esophageal sphincter (UES) problem that mainly occurs in the upright position during periods of physical exertion (eg, bending over, Valsalva, exercise). In contrast, GERD is felt to be a problem of the lower esophageal sphincter and mainly occurs in a recumbent position. There appears to be a lower incidence of esophageal dysmotility in LPR versus GERD.

Respiratory tract infection — Cough following viral or other upper respiratory tract infection can persist for more than eight weeks after the acute infection [52]. Such cases increase in frequency during outbreaks of Mycoplasma pneumoniae, Chlamydia pneumoniae, and Bordetella pertussis [1,53,54].

Pertussis is a common, but under recognized, cause of persistent cough in adolescents and adults [59]. In the United States, the recognition of pertussis in adolescents and adults has increased dramatically over the past decade [60,61]. In one series of 75 adults with cough lasting more than two weeks, 21 percent met serologic criteria for pertussis infection despite a negative culture for Bordetella pertussis [62].

Some patients appear to have unsuspected bacterial suppurative disease of the large airways, in the absence of bronchiectasis, as a cause of chronic cough. Bronchoscopic evaluation and microbiologic sampling of the airways led to this diagnosis in a series of 15 patients undergoing evaluation at a single center for cough that remained unexplained after extensive evaluation [65]. While four of these patients had underlying systemic disease, the remainder had no evidence of immune compromise. Aggressive antibiotic therapy, based upon the results of bronchoscopic culture, led to improvement or elimination of the cough in all patients. The prevalence of this disorder, and the appropriate duration of antibiotic therapy, remains to be determined.

The important observation that cough does not appear to occur with increased frequency in patients treated with angiotensin II receptor antagonists (which do not increase kinin levels) is consistent with the kinin hypothesis. A review of clinical trials found that the incidence of cough with losartan was similar to that with placebo (3 to 3.4 percent) and well below that seen with ACE inhibitors (10.6 percent) [68].

ACE inhibitor-induced cough has the following general features [66]:

● It usually begins within one week of instituting therapy, but the onset can be delayed up to six months.

● It often presents with a tickling, scratchy, or itchy sensation in the throat [1].

● It typically resolves within one to four days of discontinuing therapy, but can take up to four weeks.

● It generally recurs with rechallenge, either with the same or a different ACE inhibitor.

● It is a more common complication in women than in men, and is also more common in those of Chinese ancestry [70].

● It does not occur more frequently in asthmatics than in non-asthmatics.

● It is generally not accompanied by airflow obstruction [71]. In one study, for every 10 patients with cough induced by ACE inhibitors, there was approximately one patient with development or aggravation of asthma, bronchospasm, or dyspnea [72]. Cough did not necessarily accompany these other respiratory problems.

Chronic bronchitis is defined as the presence of cough and sputum production on most days over at least a three-month period for more than two consecutive years in a patient without other explanations for cough. Almost all patients are smokers, except a small number who have chronic exposure to and airway inflammation due to other fumes or dusts. Because of the high prevalence of smoking, chronic bronchitis remains one of the most frequent causes of chronic cough

However, most smokers with chronic bronchitis do not seek medical attention for their cough, and in most series of chronic cough, chronic bronchitis accounts for 5 percent or less of cases [2].

The sputum produced is usually clear or white. A purulent appearance to sputum often suggests a concomitant upper or lower respiratory infection, such as acute bronchitis, bronchiectasis, or sinusitis.

Bronchiectasis results from severe, repeated, or persistent airway inflammation that leads to progressive airway damage. Bronchi become dilated and cystic, leading to poor mucus clearance, secretion pooling, and chronic infection of the lower respiratory tract. This, in turn, serves to worsen airway inflammation and bronchial destruction.

Cough is a major symptom of bronchiectasis, and in some studies, bronchiectasis is the cause of chronic cough in 4 percent of patients [2,73]. While some patients with bronchiectasis have only a dry cough, most produce chronic sputum that is mucopurulent, and which becomes frankly purulent during an exacerbation. The lung examination may be surprisingly normal, but more often reveals focal or bilateral rhonchi, crackles, or wheezes.

Once bronchiectasis is diagnosed, one should attempt to define its cause. Focal bronchiectasis is often the result of a prolonged or severe remote lower respiratory infection. Multifocal bronchiectasis, especially in a middle aged woman, is often due to chronic lower airway infection with Mycobacterium avium complex (MAC). More diffuse bronchiectasis, especially in a younger individual, raises the possibility of cystic fibrosis or an immunoglobulin deficiency state.

Bronchogenic carcinoma is a feared diagnosis in which cough is present in a significant number of cases [74]. However, lung cancer is the etiology in less than 2 percent of the cases of chronic cough [1,2,74]. Most cases of lung cancer that manifest with cough are due to neoplasms originating in the large central airways, where cough receptors are common

Physical examination may reveal focal wheezing or diminished breath sounds, indicative of focal airway obstruction from tumor. Pulmonary lymphangitic carcinomatosis from extrapulmonary malignancies can also present as cough, but is generally accompanied by dyspnea.

Bronchogenic cancer should be considered as a possible etiology of cough in any current or former smoker, and should be particularly suspected in those with:

● A new cough or a recent change in chronic "smoker's cough"

● A cough that persists more than one month following smoking cessation

● Hemoptysis that does not occur in the setting of an airway infection

Nonasthmatic eosinophilic bronchitis is an increasingly recognized cause of chronic nonproductive cough, particularly in patients who lack any of the risk factors described above [75-79]. Patients with this disorder demonstrate atopic tendencies, with elevated sputum eosinophils and active airway inflammation in the absence of airway hyperresponsiveness [75]. These same findings with evidence of hyperresponsiveness are consistent with the diagnosis of cough-variant asthma [76].

In one series of 20 patients with chronic isolated (nonspecific) cough, no apparent cause, and no airway hyperresponsiveness, bronchial biopsy revealed eosinophilic bronchitis in 16 [75].

Although bronchial mucosal biopsies are required to definitively diagnose eosinophilic bronchitis, a trial of therapy is usually performed without biopsy, since most patients respond well to inhaled glucocorticoids [77,80]. Airway eosinophils and basement membrane thickening are present in both asthma and eosinophilic bronchitis, but mast cell infiltration is noted only in asthmatics, which may explain the differences in airway reactivity [81-83].

The natural history of nonasthmatic eosinophilic bronchitis is variable. One year follow-up of a cohort of 36 patients with normal lung function and eosinophilic inflammation noted that 17 (55 percent) remained symptomatic with normal lung function, 10 (32 percent) were free of symptoms, and 4 (13 percent) developed asthma [84]. Patients with recurrent episodes of symptomatic eosinophilic bronchitis appear to be at increased risk of asthma and chronic airway obstruction [85].

Linear Algebra Is Important in Machine Learning There is no doubt that linear algebra is important in machine learning. Linear algebra is the mathematics of data. It’s all vectors and matrices of numbers. Modern statistics is described using the notation of linear algebra and modern statistical methods harness the tools of linear algebra. Modern machine learning methods are described the same way, using the notations and tools drawn directly from linear algebra. Even some classical methods used in the field, such as linear regression via linear least squares and singular-value decomposition, are linear algebra methods, and other methods, such as principal component analysis, were born from the marriage of linear algebra and statistics. To read and understand machine learning, you must be able to read and understand linear algebra

Practitioners Study Linear Algebra Too Early If you ask how to get started in machine learning, you will very likely be told to start with linear algebra. We know that knowledge of linear algebra is critically important, but it does not have to be the place to start. Learning linear algebra first, then calculus, probability, statistics, and eventually machine learning theory is a long and slow bottom-up path. A better fit for developers is to start with systematic procedures that get results, and work back to the deeper understanding of theory, using working results as a context. I call this the top-down or results-first approach to machine learning, and linear algebra is not the first step, but perhaps the second or third

Practitioners Study Too Much Linear Algebra When practitioners do circle back to study linear algebra, they learn far more of the field than is required for or relevant to machine learning. Linear algebra is a large field of study that has tendrils into engineering, physics and quantum physics. There are also theorems and derivations for nearly everything, most of which will not help you get better skill from or a deeper understanding of your machine learning model. Only a specific subset of linear algebra is required, though you can always go deeper once you have the basics.

Welcome Welcome to Basics of Linear Algebra for Machine Learning. Linear algebra is a pillar of machine learning. The field started to be formalized about 150 years ago, but it was only about 70 years ago that modern linear algebra came into existence. It’s a huge field of study that has made an impact on other areas of mathematics, such as statistics, as well as engineering and physics. Thankfully, we don’t need to know the breadth and depth of the field of linear algebra in order to improve our understanding and application of machine learning. I designed this book to teach you step-by-step the basics of linear algebra with concrete and executable examples in Python

A = ((a 1,1 , a 1,2 ), (a 2,1 , a 2,2 ), (a 3,1 , a 3,2 ))

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A lease is a contractual arrangement calling for the lessee (user) to pay the lessor (owner) for use of an asset

The lessor is the legal owner of the asset, while the lessee obtains the right to use the asset in return for regular rental payments

Enfranchisement is the obtaining of the landlord's title and is most commonly negotiated with the landlord where a tenant pays only a ground rent.

Many organizations and companies use lease financing for the acquisition and use of many types of equipment, including manufacturing and mining machinery, vessels and containers, construction and off-road equipment, medical technology and equipment, agricultural equipment, aircraft, rail cars and rolling stock, trucks and transportation equipment, business, retail and office equipment, IT equipment and software.