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Medium 9781449332426

7. Outside Connectivity

Russell Bryant O'Reilly Media ePub

You cannot always control what goes on outside. But you can always control what goes on inside.

In the previous chapters, we have covered a lot of important information that is essential to a working Asterisk system. However, we have yet to accomplish the one thing that is vital to any useful PBX: namely, connecting it to the outside world. In this chapter we will rectify that situation.

The architecture of Asterisk is significant, due in large part to the fact that it treats all channel types as equal. This is in contrast to a traditional PBX, where trunks (which connect to the outside world) and extensions (which connect to users and resources) are very different. The fact that the Asterisk dialplan treats all channels in a similar manner means that in an Asterisk system you can accomplish very easily things that are much more difficult (or impossible) to achieve on a traditional PBX.

This flexibility does come with a price, however. Since the system does not inherently know the difference between an internal resource (such as a telephone set) and an external resource (such as a telco circuit), it is up to you to ensure that your dialplan handles each type of resource appropriately.

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Medium 9781855753532

CHAPTER EIGHT: Trauma, memory, and the brain

Anne Kearns Karnac Books ePub

In my early teens I, like most other Americans, was bombarded night after night on the six o’clock news by the atrocities taking place in Vietnam. It was hard to imagine then that anything good would come out of America’s extended ‘police action’ there. Once the Americans pulled out of Vietnam and turned their attention to the Middle East, and to the oil that replaced Communism as the new national obsession, Vietnam was rapidly forgotten. In New York, where I lived, returning war veterans were usually honoured by a hero’s welcome complete with what’s known as a ‘ticker-tape’ parade through the financial district. This did not happen for the Vietnam veterans until ten or so years after they came home, once someone made the connection that the way the young men who had fought in Vietnam were ignored on their return by a nation that was on some level ashamed to acknowledge them contributed to their posttraumatic experience. Just like the soldiers who returned from the First World War suffering from ‘shell shock spurred an interest in the clinical treatment of trauma, so id the Vietnam vets. Three out of four who had experiénced heavy combat with its associated atrocities suffered symptoms of what came to be known as post-traumatic stress disorder (PTSD).

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Medium 9780253211859

The Problem of Logical Subject-Matter from Logic: The Theory of Inquiry (1938)

Larry A Hickman Indiana University Press ePub

Contemporary logical theory is marked by an apparent paradox. There is general agreement as to its proximate subject-matter. With respect to this proximate subject-matter no period shows a more confident advance. Its ultimate subject-matter, on the other hand, is involved in controversies which show little sign of abating. Proximate subject-matter is the domain of the relations of propositions to one another, such as affirmation-negation, inclusion-exclusion, particular-general, etc. No one doubts that the relations expressed by such words as is, is-not, if-then, only (none but), and, or, some-all, belong to the subject-matter of logic in a way so distinctive as to mark off a special field.

When, however, it is asked how and why the matters designated by these terms form the subject-matter of logic, dissension takes the place of consensus. Do they stand for pure forms, forms that have independent subsistence, or are the forms in question forms of subject-matter? If the latter, what is that of which they are forms, and what happens when subject-matter takes on logical form? How and why?

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Medium 9781626563377

Resource 1: The Case for SRI

Hal Brill Berrett-Koehler Publishers ePub

AS CHAMPIONS OF SUSTAINABLE AND RESPONSIBLE INVESTING FOR 25 years, we embrace the goal of bringing your financial investment portfolio into harmony with the choices you are making across the entire Resilient Investing Map. As we noted in chapter 3, we feel that in this time of global challenges, it is crucial for corporations, financial institutions, and investors to take responsibility for the social and environmental consequences of their actions. SRI’s combination of community investing, positive and negative screening (filtering companies based on issues and activities investors wish to support or avoid), and shareholder advocacy (direct engagement with corporate management) has helped reform capitalism while providing investors with an avenue to bring their money and their values into closer alignment.

SRI emerged in the early 1970s as a protest against the Vietnam War and a desire to avoid investing in military contractors; today a wide array of environmental, social, and governance (ESG) factors are assessed by SRI and conventional money managers as metrics that add value to their investment selection process. Environmental and resource-related concerns are increasingly being seen by the financial world as risks to corporate strategy.

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Medium 9780596513986

24. Class Coding Details

Mark Lutz O'Reilly Media ePub

If you did not understand all of Chapter23, don't worry; now that we've had a quick tour, we're going to dig a bit deeper and study the concepts introduced earlier in further detail. In this chapter, we'll take another look at classes and methods, inheritance, and operator overloading, formalizing and expanding on some of the class coding ideas introduced in Chapter23. Because the class is our last namespace tool, we'll summarize the concepts of namespaces in Python here as well. This chapter will also present some larger and more realistic classes than those we have seen so far, including a final example that ties together much of what we've learned about OOP.

Although the Python class statement may seem similar to tools in other OOP languages on the surface, on closer inspection, it is quite different from what some programmers are used to. For example, as in C++, the class statement is Python's main OOP tool, but unlike in C++, Python's class is not a declaration. Like a def, a class statement is an object builder, and an implicit assignmentwhen run, it generates a class object, and stores a reference to it in the name used in the header. Also, like a def, a class statement is true executable codeyour class doesn't exist until Python reaches and runs the class statement that defines it (typically while importing the module it is coded in, but not before).

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