The Question of a Balanced Budget

The Duality of Memory and Communicationin the Implementation of aMultiprocessor Operating SystemMichael Young, Avadis Tevanian, Richard Rashid, David Golub,Jeffrey Eppinger, Jonathan Chew, William Bolosky, David Black and Robert BaronComputer Science DepartmentCarnegie-Mellon UniversityPittsburgh, PA 15213Appeared in Proceedings of the 11th Operating Systems Principles,November, 1987AbstractMach is a multiprocessor operating system being implemented at Carnegie-Mellon University. An importantcomponent of the Mach design is the use of memory objects which can be managed either by the kernel or by userprograms through a message interface. This feature allows applications such as transaction management systems toparticipate in decisions regarding secondary storage management and page replacement.This paper explores the goals, design and implementation of Mach and its external memory management facility.The relationship between memory and communication in Mach is examined as it relates to overall performance,applicability of Mach to new multiprocessor architectures, and the structure of application programs.This research was sponsored by the Defense Advanced Research Projects Agency (DOD), ARPA Order No.4864, monitored by the Space and Naval Warfare Systems Command under contract N00039-85-C-1034. Theviews expressed are those of the authors alone.Permission to copy without fee all or part of this material is granted provided that the copies are not madeor distributed for direct commercial advantage, the ACM copyright notice and the title of the publication andits date appear, and notice is given that copying is by permission of the Association of Computing Machinery.To copy otherwise, or to republish, requires a fee and/or specific permission. 11. IntroductionIn late 1984, we began implementation of an operating system called Mach. Our goals for Mach were:• an object oriented interface with a small number of basic system objects,• support for both distributed computing and multiprocessing,• portability to a wide range of multiprocessor and uniprocessor architectures,• compatibility with Berkeley UNIX, and• performance comparable to commercial UNIX offerings.Most of these early goals have been met. The underlying Mach kernel is based on five interrelated abstractions;operations on Mach objects are invoked through message passing. Mach runs on the majority of workstations andmainframes within the Department of Computer Science, and supports projects in distributed computing and parallelprocessing such as the Camelot distributed transaction processing system [21], the Agora parallel speechunderstanding system [3] and a parallel implementation of OPS5 [7]. Mach has already been ported to more than a1dozen computer systems including ten members of the VAX family of uniprocessors and multiprocessors , the IBMRT PC, the SUN 3, the 16-processor Encore MultiMax , and the 26-processor Sequent Balance 21000. Mach isbinary compatible with Berkeley UNIX 4.3bsd and has The Question of a Balanced Budget The Question of a Balanced Budget By: OpenStaxCollege For many decades, going back to the 1930s, proposals have been put forward to require that the U.S government balance its budget every year In 1995, a proposed constitutional amendment that would require a balanced budget passed the U.S House of Representatives by a wide margin, and failed in the U.S Senate by only a single vote (For the balanced budget to have become an amendment to the Constitution would have required a two-thirds vote by Congress and passage by three-quarters of the state legislatures.) Most economists view the proposals for a perpetually balanced budget with bemusement After all, in the short term, economists would expect the budget deficits and surpluses to fluctuate up and down with the economy and the automatic stabilizers Economic recessions should automatically lead to larger budget deficits or smaller budget surpluses, while economic booms lead to smaller deficits or larger surpluses A requirement that the budget be balanced each and every year would prevent these automatic stabilizers from working and would worsen the severity of economic fluctuations Some supporters of the balanced budget amendment like to argue that, since households must balance their own budgets, the government should too But this analogy between household and government behavior is severely flawed Most households not balance their budgets every year Some years households borrow to buy houses or cars or to pay for medical expenses or college tuition Other years they repay loans and save funds in retirement accounts After retirement, they withdraw and spend those savings Also, the government is not a household for many reasons, one of which is that the government has macroeconomic responsibilities The argument of Keynesian macroeconomic policy is that the government needs to lean against the wind, spending when times are hard and saving when times are good, for the sake of the overall economy There is also no particular reason to expect a government budget to be balanced in the medium term of a few years For example, a government may decide that by running large budget deficits, it can make crucial long-term investments in human capital and 1/3 The Question of a Balanced Budget physical infrastructure that will build the long-term productivity of a country These decisions may work out well or poorly, but they are not always irrational Such policies of ongoing government budget deficits may persist for decades As the U.S experience from the end of World War II up to about 1980 shows, it is perfectly possible to run budget deficits almost every year for decades, but as long as the percentage increases in debt are smaller than the percentage growth of GDP, the debt/GDP ratio will decline at the same time Nothing in this argument should be taken as a claim that budget deficits are always a wise policy In the short run, a government that runs a very large budget deficit can shift aggregate demand to the right and trigger severe inflation Additionally, governments may borrow for foolish or impractical reasons The Macroeconomic Impacts of Government Borrowing will discuss how large budget deficits, by reducing national saving, can in certain cases reduce economic growth and even contribute to international financial crises A requirement that the budget be balanced in each calendar year, however, is a misguided overreaction to the fear that in some cases, budget deficits can become too large No Yellowstone Park? The federal budget shutdown of 2013 illustrated the many sides to fiscal policy and the federal budget In 2013, Republicans and Democrats could not agree on which spending policies to fund and how large the government debt should be Due to the severity of the recession in 2008–2009, the fiscal stimulus, and previous policies, the federal budget deficit and debt was historically high One way to try to cut federal spending and borrowing was to refuse to raise the legal federal debt limit, or tie on conditions to appropriation bills to stop the Affordable Health Care Act This disagreement led to a two-week shutdown of the federal government and got close to the deadline where the federal government would default on its Treasury bonds Finally, however, a compromise emerged and default was avoided This shows clearly how closely fiscal policies are tied to politics Key Concepts and Summary Balanced budget amendments are a popular political idea, but the economic merits behind such proposals are questionable Most economists accept that fiscal policy needs to be flexible enough to accommodate unforeseen expenditures, such as wars or recessions While persistent, large budget deficits can indeed be a problem, a balanced budget amendment prevents even small, temporary deficits that might, in some cases, be necessary 2/3 The Question of a Balanced Budget Self-Check Questions How would a balanced budget amendment affect a decision by ...Wireless CommunicationsUnderstanding Radio Frequency Communications 2Objectives•List the components of a radio system•Describe how different factors affect the design of a radio system•Explain the radio frequency spectrum 3Components of a Radio System•Components include:–Filters–Mixers–Amplifiers–Antennas 4Filters•Filter–Removes unwanted RF signals•RF filter–Either passes or rejects a signal based on frequency•Types of filters–Low-pass filter–High-pass filter–Bandpass filter 5Mixers•Combine two radio frequency inputs to create a single output–Output is in the range of the highest sum and the lowest difference of the two frequencies–Sum and differences are known as the sidebands of the frequency carrier•Shield transmitted signal from “stray” signals•Used to convert an input frequency to a specific desired output frequency 6Mixers (continued) 7Amplifiers•Increase the amplitude of an RF signal•RF signals tend to lose intensity (amplitude)–When they move through circuits, air, or space•Amplifier is an active device–Must be supplied with electricity•Increases a signal’s intensity or strength–By using the input signal to control a circuit that “shapes” the output•To reflect the shape of the input signal exactly 8Amplifiers (continued) 9Antennas•Transmit or receive an RF signal 10Multiple Access•Only a limited number of frequencies are available for radio transmission–Conserving the use of frequencies is important•Conserving a frequency–Share a frequency among several individual users•Methods that allow multiple access–Frequency Division Multiple Access (FDMA)–Time Division Multiple Access (TDMA)–Code Division Multiple Access (CDMA) [...]... signal strength falls near the level of noise – Interference can take place • To reduce the interference of noise – Boost the strength of the signal – Use of filters when receiving the signal • Attenuation – A loss of signal strength • Multipath distortion – As a radio signal is transmitted, the electromagnetic waves spread out 13 Multiple Access (continued) • Time Division Multiple Access (TDMA) – Divides... (TDMA) – Divides the transmission time into several slots – Each user is assigned the entire frequency for the transmission • For a fraction of time on a fixed, rotating basis – Advantages • Uses the bandwidth more efficiently • Allows both data and voice transmissions to be mixed using the same frequency 14 Multiple Access (continued) 3 Components of a Radio System • Components include: – Filters – Mixers – Amplifiers – Antennas ... include: – Filters – Mixers – Amplifiers – Antennas 22 Signal Strength • Strength of the signal in a radio system – Must be sufficient for the signal to reach its destination • With enough amplitude to be picked up by the antenna • And for the information to be extracted from it • Electromagnetic interference (EMI) – One factor that affects radio P1: RNK0521864381pre CUNY780B-African 978 0 521 68297 8 May 15, 2007 19:34iiThis page intentionally left blank P1: RNK0521864381pre CUNY780B-African 978 0 521 68297 8 May 15, 2007 19:34africans, second editionInavast and all-embracing studyof Africa, from the origins of mankind to the AIDSepidemic, John Iliffe refocuses its history on the peopling of an environmentallyhostile continent.Africanshavebeenpioneersstrugglingagainstdiseaseandnature,and their social, economic, and political institutions have been designed to ensuretheir survival. In the context of medical progress and other twentieth-centuryinnovations, however, the same institutions have bred the most rapid populationgrowth the world has ever seen. The history of the continent is thus a single storybinding living Africans to their earliest human ancestors.John Iliffe was Professor of African History at the University of Cambridge and is aFellow of St. John’s College. He is the author of several books on Africa, includingAmodern history of Tanganyika and The African poor: A history,which was awardedthe Herskovits Prize of the African Studies Association of the United States. Bothbooks were published by Cambridge University Press.i P1: RNK0521864381pre CUNY780B-African 978 0 521 68297 8 May 15, 2007 19:34ii P1: RNK0521864381pre CUNY780B-African 978 0 521 68297 8 May 15, 2007 19:34african studiesThe African Studies Series,founded in 1968 in collaboration with the African StudiesCentre of the University of Cambridge, is a prestigious series of monographs andgeneral studies on Africa covering history, anthropology, economics, sociology,and political science.editorial boardDr. David Anderson, St. Antony’s College, OxfordProfessor Carolyn Brown, Department of History, Rutgers UniversityProfessor Christopher Clapham, Centre of African Studies, Cambridge UniversityProfessor Michael Gomez, Department of History, New York UniversityProfessor David Robinson, Department of History, Michigan State UniversityProfessor Leonardo A. Villalon, Center for African Studies, University of FloridaA list of books in this series will be found at the end of this volume.iii P1: RNK0521864381pre CUNY780B-African 978 0 521 68297 8 May 15, 2007 19:34iv P1: RNK0521864381pre CUNY780B-African 978 0 521 68297 8 May 15, 2007 19:34AfricansTHE HISTORY OF ACONTINENTSecond Editionjohn iliffeFellow of St. John’s College, Cambridgev CAMBRIDGE UNIVERSITY PRESSCambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São PauloCambridge University PressThe Edinburgh Building, Cambridge CB2 8RU, UKFirst published in print formatISBN-13 978-0-521-86438-1ISBN-13 978-0-511-34916-4© John Iliffe 1995, 20072007Information on this title: www.cambridge.org/9780521864381This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.ISBN-10 0-511-34916-5ISBN-10 0-521-86438-0Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.Published in the United States of America by Cambridge University guest the meaning of a word Could you guest the sign of a new word? Yes, Of couse. This is 20 prefix and 14 root-word helping you improve your vocabulary.You can guest the meaning of 14.000 words , which is in the dictiônary for sutdents, and 100000 words in the big dictionary.( following to James Ị Brown , Minesota, Programmed Vocabulary, Meredith buplish , NewYork 1971). Here are 14 root_word:precept: pre- và capere [Mặc dù cep, cip, ceiv, ceipt, và ceit là các biến dạng của capere,nhưng dạng thông dụng nhất thường được dùng là cap (Latin: head, chief, get, receive)].detain: de-và tenere [Biến dạng của tenere là ten, tain, và tin (Latin: hold, grasp, have)].intermittent: inter-và mittere [Các biến dạng khác bao gồm mitt, mit, miss, mis, và mise(Latin:send, let go, cause to go; throw, hurl, cast)].offer: ob-và ferre [Gồm các biến dạng fer và lat (Latin: line, bring, carry)].insist: in-và stare [Các biến dạng của stare là sta, stat, sti, và sist (Greek: standing, stay,make firm, fixed)].monograph: mono-và graphein [Các biến dạng thông dụng bao gồm graph và gram (Greek:to scratch; write, record, draw, describe)].epilogue: epi-và legein [Gồm các biến dạng sau: log, logy, logo, logue, và ology (Greek: talk,speech, speak; word)].aspect: ad-và specere [Gồm có 2 dạng spec và spic (Latin: see, sight, look, appear, behold,and examine)].uncomplicated: un-, com-,và plicare [Có 11 biến dạng sau: plic, plicat, plicit, pli, ply, plex, ple,pleat, play, ploy, và plicity (Latin: layer, involved]nonextended: non-, ex-,và tendere [Gồm 3 dạng tend, tent, và tens (Latin: stretch)].reproduction: re-, pro-,và ducere [Mặc dù duit, duke, duct, duch, và duce là các biến dạng củaducere, nhưng tần suất cao nhất lại rơi vào duc (Latin: lead, leading, bring, take, draw)].indisposed: in-, dis-,và ponere [Hai dạng thông dụng nhất chỉ dùng 3 ký tự của ponere là ponvà pos (Latin: set, place); pound và post ít sử dụng hơn vì chúng có thể dẽ bị nhầm lẫn vớipost trong nghĩa “after, behind”(sau)].oversufficient: over-, sub-,và facere [Có các biến dạng fac, fact, fic, feat, feas, featur, và fair(Latin: make, do, build, cause, produce; forming, shaping)].mistranscribe: mis-, trans-,và scribere [Biến dạng thông dụng scrib, scrip, scrip, và biến dạngít dùng scriv (Latin: write, record)].Besides, 14 prefix usually use to form a word :ab- (away from)be- (on all sides, overly)de- (reversal, undoing, downward) dis-, dif- (not, reversal)ex- (out of, former)pre- (before)re- (again, restore)un- (do the opposite of)ad- (to, toward)com-, con-, co- (with, together)en-, em- (in, into, to cover or contain)in- (into, not)pro- (in favor of, before)sub- (under, beneath) A simple proof for the existence of exponentially balanced Gray codes I Nengah Suparta ∗ Department of Applied Mathematics Faculty of Electrical Engineering, Mathematics and Computer Science Delft University of Technology P.O. BOX 5031, 2600 GA Delft, The Netherlands N.Suparta@ewi.tudelft.nl Submitted: Apr 21, 2005; Accepted: Sep 9, 2005; Published: Oct 13, 2005 Mathematics Subject Classifications: 94A05, 94A12, 94A15, 94C30 Abstract AGraycodeoflengthn is a circular list of all 2 n bitstrings or binary codewords of length n such that successive codewords differ in only one bit position. The fre- quencies of the positions where these differences occur are called transition counts. An exponentially balanced Gray code is a Gray code the transition counts of which are all the same power of two, or are two successive powers of two. A proof for the existence of exponentially balanced Gray codes is derived. The proof is much sim- pler than an earlier proof presented by van Zanten and Suparta (Discrete Analysis and Operation Research, 11 (2004) 81-98 (Russian Journal)). Keywords: Gray codes, exponentially balanced Gray codes, transition count spec- trum. 1 Introduction A Gray code G(n)oflengthn is a circular list of all 2 n bitstrings or binary codewords of length n such that successive codewords differ in one bit position. The frequencies of the positions where these differences occur are called transition counts in [2, 4, 11]. If a Gray code is such that any two transition counts differ at most two, one says that this Gray code is balanced, and it is called totally balanced or uniform if all its transition counts are equal (cf. [2, 11]). The transition counts can be called exponentially close if they are all the same power of two, or are all two consecutive powers of two. We call a Gray code ∗ On leave from Dept. of Mathematics, IKIP Negeri Singaraja, Bali - Indonesia the electronic journal of combinatorics 12 (2005), #N19 1 with this property an exponentially balanced Gray code (cf. [10]), as a generalization of (totally) balanced Gray codes. Thus, for an exponentially balanced Gray code G(n)one has that the transition count of every bit position i,1≤ i ≤ n, is equal to 2 e(i) for some positive integer e(i), and |e(i) − e(j)|≤1, 1 ≤ i, j ≤ n. It was proved in [10, Theorem 4] that a Gray code G(n) is totally balanced if and only if e(i)=e(j) for all i, j. In [11], Wagner and West conjectured that exponentially balanced Gray codes exist for all length n. By extending the method of Robinson and Cohn for the construction of Gray codes in [5], van Zanten and Suparta in [10] proved the conjecture of Wagner and West in positive sense. In this note we present a proof based on Bakos’s construction of Gray codes in [1] which was reformulated in a simple way by Knuth in [4, Theorem D]. This proof is much simpler than the one given in [10]. In the sequel, codewords in a Gray code G(n) will be indexed from 0 to 2 n − 1. The codeword with index i,0≤ i ≤ 2 n − 1, is denoted by x i ,whereasx 0 is identified with x 2 n . Let s i ,1≤ i ≤ 2 n , be the bit position where codewords x i−1 and x i differ in the list of G(n). We call the integers s i , transition numbers or shortly transitions. The sequence of transitions s i ,1≤ i ≤ 2 n , denoted by ¯ S(n):=s 1 ,s 2 , , s 2 n , is called the transition sequence of G(n). The last transition s 2 n is occasionally called the closing transition of ¯ S(n). Moreover, we write ¯ S(n) j ,0≤ j ≤ 2 n − 1, for the cyclic shift of ¯ S(n)overj po- sitions to the left. For instance, the 3-bit Gray code 000, 001, 011, 010, 110, 111, 101, 100, has transition sequence ¯ S(3) = 3, 2, 3, 1, 3, 2, 3, 1, while ¯ S(3) 3 =1, 3, 2, 3, 1, 3, 2, 3. With respect to the transition sequence of G(n), the transition count of the integer i, denoted by TC n (i), is equal to the number of times the integer i occurs in ¯ S(n). The distribu- tion TC n :=(TC n (1),TC n (2), , T C n (n)) of the transition counts of G(n) is called the transition ... deficits that might, in some cases, be necessary 2/3 The Question of a Balanced Budget Self-Check Questions How would a balanced budget amendment affect a decision by Congress to grant a tax cut... reducing national saving, can in certain cases reduce economic growth and even contribute to international financial crises A requirement that the budget be balanced in each calendar year, however,... this argument should be taken as a claim that budget deficits are always a wise policy In the short run, a government that runs a very large budget deficit can shift aggregate demand to the right