System Processes and Memory Management Objectives Upon completion of this module, you should be able to: • Identify processes on your system using the ps command • Find a process using the pgrep command • Control processes using the jobs command • Terminate unwanted processes using the kill and pkill commands Discussion – At times an application that you are running will freeze or cause your system to become inaccessible. How would you regain control of your workstation? System Process Overview Each task you perform in the Linux environment starts a process. An example of a process is using vi to edit a letter, or sending a file to the printer. Each process is assigned a unique process identification number (PID), which is used by the system to identify the process. The following pages define useful commands on how to locate a process and terminate processes. Process Hierarchy There are five types of processes on a Linux system: • Daemon • Parent • Child • Orphan • Zombie or defunct Daemon processes are processes that are started by the kernel and exist for a specific purpose. For instance, the lpd daemon exists for the sole purpose of handling print jobs. When no printing is taking place on the system, the lpd daemon is running but inactive. When a print job is submitted, this daemon becomes active until the job is finished. The login daemon provides the CDE login screen at the beginning of a user’s session and again after the user exits CDE. Following system boot-up, a process called init is invoked. This process is at the top of the process hierarchy and is responsible for spawning many system processes. The login daemon is spawned by init and init is, therefore, referred to as the parent process of the login daemon. When a user is working in a terminal window in CDE, that terminal’s PID is the parent process ID (PPID) of any commands issued in the terminal. These commands are child processes of the terminal process. The parent process receives and displays the output from the child process and then “kills” the process. If a command is issued in a terminal window and the window is closed before the command returns output, that process becomes an orphan. The system passes the orphan process to init which then becomes the parent process and terminates the child process. Occasionally a child process does not return to the parent process with its output. This process becomes “lost” in the system. The only resource this process uses is a slot in the process table; it cannot be stopped in a conventional manner. This type of process is called a zombie or defunct process. The only way to kill a defunct process is to reboot the system. Processes and PIDs Use the ps command to list the processes currently running on the system. The output of this command will display the PID number and the command associated with it. Many times a PID number is needed for use with the kill command . Command Format ps [-options] Options -e Print information about every process on the system. -f Generate a full listing. (Refer to the man pages for a description of the headings displayed.) Because of the number of processes usually running on a system, it is useful to pipe the ps -ef command to more so that the output can be read a page at a time, as in the example on the next page. Displaying a Full Listing of All Processes $ ps -ef | more UID PID PPID C STIME TTY TIME CMD root 0 0 80 16:46:41 ? 0:01 sched root 1 0 80 16:46:44 ? 0:40 /etc/init - root 2 0 27 16:46:44 ? 0:00 pageout root 3 0 80 16:46:44 ? 4:33 fsflush root 236 1 80 16:48:08 ? 0:01 /usr/lib/saf/sac root 844 1 54 12:12:10 ? 0:00 /usr/lib/lpsched aster 1292 1 80 06:48:51 console 0:01 -ksh root 241 236 69 16:48:14 ? 0:01 /usr/lib/saf/ttymon rose Digestive System Processes and Regulation Digestive System Processes and Regulation Bởi: OpenStaxCollege The digestive system uses mechanical and chemical activities to break food down into absorbable substances during its journey through the digestive system [link] provides an overview of the basic functions of the digestive organs Visit this site for an overview of digestion of food in different regions of the digestive tract Note the route of non-fat nutrients from the small intestine to their release as nutrients to the body Functions of the Digestive Organs Organ Mouth Major functions • Ingests food • Chews and mixes food • Begins chemical breakdown of carbohydrates • Moves food into the pharynx • Begins breakdown of lipids via lingual lipase Other functions • Moistens and dissolves food, allowing you to taste it • Cleans and lubricates the teeth and oral cavity • Has some antimicrobial activity 1/9 Digestive System Processes and Regulation Functions of the Digestive Organs Organ Major functions Other functions Pharynx • Propels food from the oral cavity to the esophagus • Lubricates food and passageways Esophagus • Propels food to the stomach • Lubricates food and passageways Stomach • Mixes and churns food with gastric juices to form chyme • Begins chemical breakdown of proteins • Releases food into the duodenum as chyme • Absorbs some fat-soluble substances (for example, alcohol, aspirin) • Possesses antimicrobial functions • Stimulates proteindigesting enzymes • Secretes intrinsic factor required for vitamin B12 absorption in small intestine Small intestine • Mixes chyme with digestive juices • Propels food at a rate slow enough for digestion and absorption • Absorbs breakdown products of carbohydrates, proteins, lipids, and nucleic acids, along with vitamins, minerals, and water • Performs physical digestion via segmentation • Provides optimal medium for enzymatic activity Accessory organs • Liver: produces bile salts, which emulsify lipids, aiding their digestion and absorption • Gallbladder: stores, concentrates, and releases bile • Bicarbonate-rich pancreatic juices help neutralize acidic chyme and provide optimal environment for enzymatic activity 2/9 Digestive System Processes and Regulation Functions of the Digestive Organs Organ Major functions Other functions • Pancreas: produces digestive enzymes and bicarbonate Large intestine • Further breaks down food residues • Absorbs most residual water, electrolytes, and vitamins produced by enteric bacteria • Propels feces toward rectum • Eliminates feces • Food residue is concentrated and temporarily stored prior to defecation • Mucus eases passage of feces through colon Digestive Processes The processes of digestion include six activities: ingestion, propulsion, mechanical or physical digestion, chemical digestion, absorption, and defecation The first of these processes, ingestion, refers to the entry of food into the alimentary canal through the mouth There, the food is chewed and mixed with saliva, which contains enzymes that begin breaking down the carbohydrates in the food plus some lipid digestion via lingual lipase Chewing increases the surface area of the food and allows an appropriately sized bolus to be produced Food leaves the mouth when the tongue and pharyngeal muscles propel it into the esophagus This act of swallowing, the last voluntary act until defecation, is an example of propulsion, which refers to the movement of food through the digestive tract It includes both the voluntary process of swallowing and the involuntary process of peristalsis Peristalsis consists of sequential, alternating waves of contraction and relaxation of alimentary wall smooth muscles, which act to propel food along ([link]) These waves also play a role in mixing food with digestive juices Peristalsis is so powerful that foods and liquids you swallow enter your stomach even if you are standing on your head 3/9 Digestive System Processes and Regulation Peristalsis Peristalsis moves food through the digestive tract with alternating waves of muscle contraction and relaxation Digestion includes both mechanical and chemical processes Mechanical digestion is a purely physical process that does not change the chemical nature of the food Instead, it makes the food smaller to increase both surface area and mobility It includes mastication, or chewing, as well as tongue movements that help break food into smaller bits and mix food with saliva Although there may be a tendency to think that mechanical digestion is limited to the first steps of the digestive process, it occurs after the food leaves the mouth, as well The mechanical churning of food in the stomach serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme Segmentation, which occurs mainly in the small intestine, consists of localized contractions of circular muscle of the muscularis layer of the alimentary canal These contractions ...Presence and regulation of the endocannabinoid system in human dendritic cells Isabel Matias 1 , Pierre Pochard 2 , Pierangelo Orlando 3 , Michel Salzet 4 , Joel Pestel 2 and Vincenzo Di Marzo 1 1 Endocannabinoid Research Group, 1 Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli (Napoli), Italy; 2 Inflammatory Reaction and Allergic diseases Department, INSERM unit, Pasteur Institute, Lille, France; 3 Istituto di Biochimica delle Proteine ed Enzimologia, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli (Napoli), Italy; 4 Laboratoire de Neuroimmunite ´ des Anne ´ lides, UMR 8017 CNRS, Universite ´ des Sciences et Technologies de Lille, Villeneuve d’Ascq, France Cannabinoid receptors and their endogenous ligands, the endocannabinoids, have been detected in several blood immune cells, including monocytes/macrophages, basophils and lymphocytes. However, their presence in dendritic cells, which play a key role in the initiation and development of the immune response, has never been in- vestigated. Here we have analyzed human dendritic cells for the presence of the endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG), the cannabinoid CB 1 and CB 2 receptors, and one of the enzymes mostly responsible for endocannabinoid hydrolysis, the fatty acid amide hydrolase (FAAH). By using a very sensitive liquid chromatography-atmospheric pressure chemical ioniza- tion-mass spectrometric (LC-APCI-MS) method, lipids extracted from immature dendritic cells were shown to contain 2-AG, anandamide and the anti-inflammatory anandamide congener, N-palmitoylethanolamine (PalEtn) (2.1 ± 1.0, 0.14 ± 0.02 and 8.2 ± 3.9 pmolÆ10 )7 cells, respectively). The amounts of 2-AG, but not anandamide or PalEtn, were significantly increased following cell maturation induced by bacterial lipopolysaccharide (LPS) or the allergen Der p 1 (2.8- and 1.9-fold, respectively). By using both RT-PCR and Western immunoblotting, den- dritic cells were also found to express measurable amounts of CB 1 and CB 2 receptors and of FAAH. Cell maturation did not consistently modify the expression of these pro- teins, although in some cell preparations a decrease of the levels of both CB 1 and CB 2 mRNA transcripts was observed after LPS stimulation. These findings demon- strate for the first time that the endogenous cannabinoid system is present in human dendritic cells and can be regulated by cell activation. Keywords: anandamide; 2-arachidonoylglycerol; cannabi- noid; receptor; fatty acid amide hydrolase. The D 9 -tetrahydrocannabinol (THC), the major psychoac- tive component of Cannabis sativa, has been reported to have beneficial effects on the treatment of nausea, glauco- ma, hypertension, migraine, neurological disorders (i.e. epilepsy, Huntington’s disease, Tourette’s syndrome, dys- tonia and Parkinson’s disease) and pain [1], and to play a down-regulatory role on the immune system [2]. Indeed, cannabinoids exhibit immunosuppressive properties and in vitro they weaken humoral immunity [3,4], cell-mediated immunity [5,6] and cellular defenses against infectious agents [7,8]. A modulation of the cytokine network and a decrease of T- and B-cell proliferation have been described in vitro [9]. A reduction of the cytolytic activity of natural killer cells and of antigen presentation was also observed, again in vitro [9]. The endocannabinoid system, comprising membrane receptors 1 Processes and Threads Chapter 2 2.1 Processes 2.2 Threads 2.3 Interprocess communication 2.4 Classical IPC problems 2.5 Scheduling 2 Processes The Process Model • Multiprogramming of four programs • Conceptual model of 4 independent, sequential processes • Only one program active at any instant 3 Process Creation Principal events that cause process creation 1. System initialization • Execution of a process creation system 1. User request to create a new process 2. Initiation of a batch job 4 Process Termination Conditions which terminate processes 1. Normal exit (voluntary) 2. Error exit (voluntary) 3. Fatal error (involuntary) 4. Killed by another process (involuntary) 5 Process Hierarchies • Parent creates a child process, child processes can create its own process • Forms a hierarchy – UNIX calls this a "process group" • Windows has no concept of process hierarchy – all processes are created equal 6 Process States (1) • Possible process states – running – blocked – ready • Transitions between states shown 7 Process States (2) • Lowest layer of process-structured OS – handles interrupts, scheduling • Above that layer are sequential processes 8 Implementation of Processes (1) Fields of a process table entry 9 Implementation of Processes (2) Skeleton of what lowest level of OS does when an interrupt occurs 10 Threads The Thread Model (1) (a) Three processes each with one thread (b) One process with three threads [...]... construct a server 16 Implementing Threads in User Space A user-level threads package 17 Implementing Threads in the Kernel A threads package managed by the kernel 18 Hybrid Implementations Multiplexing user-level threads onto kernel- level threads 19 Scheduler Activations • Goal – mimic functionality of kernel threads – gain performance of user space threads • Avoids unnecessary user/kernel transitions •... runtime system allocate threads to processors • Problem: Fundamental reliance on kernel (lower layer) calling procedures in user space (higher layer) 20 Pop-Up Threads • Creation of a new thread when message arrives (a) before message arrives (b) after message arrives 21 Making Single-Threaded Code Multithreaded (1) Conflicts between threads over the use of a global variable 22 Making Single-Threaded... Exclusion with Busy Waiting (3) Entering and leaving a critical region using the TSL instruction 29 Sleep and Wakeup Producer-consumer problem with fatal race condition 30 Semaphores The producer-consumer problem using semaphores 31 Mutexes Implementation of mutex_lock and mutex_unlock 32 Monitors (1) Example of a monitor 33 Monitors (2) • Outline of producer-consumer problem with monitors – only one... Making Single-Threaded Code Multithreaded (2) Threads can have private global variables 23 Interprocess Communication Race Conditions Two processes want to access shared memory at same time 24 Critical Regions (1) Four conditions to provide mutual exclusion 1 2 3 4 No two processes simultaneously in critical region No assumptions made about speeds or numbers of CPUs No process running outside its critical... shared by all threads in a process • Items private to each thread 11 The Thread Model (3) Each thread has its own stack 12 Thread Usage (1) A word processor with three threads 13 Thread Usage (2) A multithreaded Web server 14 Thread Usage (3) • Rough outline of code for previous slide (a) Dispatcher thread (b) Worker thread 15 Thread Usage (4) Three ways to construct a server 16 Implementing Threads in... Monitors (2) • Outline of producer-consumer problem with monitors – only one monitor procedure active at one time – buffer has N slots 34 Monitors (3) Solution to producer-consumer problem in Java (part 1) 35 Monitors (4) Solution to producer-consumer problem in Java (part 2) 36 [...]... rubric, and they were indeed unregulated Because of the complexity of the topic and the surprisingly small quantities of mortgage-backed bonds in OBSEs, we confine a discussion of their regulation to Appendix II We shall treat each of the other aspects of deregulation or nonregulation here, with sections covering subprime mortgage origination, derivatives, and the repeal of those sections of the GlassSteagall... accessible; therefore the sponsor could vary the width of the tranches to suit investor demand for risk (and thus yield) But the rating agencies’ models, while not conservative enough in the end, constituted the ultimate limit on the supply of the tranches that were most in demand the AAA tranches—because the starting points of the rating models were predictions of the rate of default on the entire pool Had the. .. agencies—Moody’s, S&P, and Fitch; and older regulations, at both the state and federal level, compelled two of the three largest classes of institutional investors—pension funds and insurance companies—to buy only highly rated securities There was no change in the legal status of the rating agencies in the run-up to the Bonuses, Irrationality, and Too-Bigness 23 crisis, so the effect of deregulation cannot... Until then, the GSEs’ spread spiked above 80 bps only twice, and usually was closer to 60 bps (ibid.) Roughly speaking, then, it seems that investors were about three times as concerned about the default risk of the banks as they were about the default risk of Fannie and Freddie As we discuss toward the end of the chapter (when we consider the ‘‘too big to fail’’ theory as a cause of the crisis), the. .. OCC OTS OTTI PLMBS SEC SIV S&P SPE SPV TARP TBTF Glossary loan-to-value ratio (of a mortgage) mark-to-market (or ``fair value'') accounting mortgage-backed security Nationally Recognized Statistical Rating Organization off balance-sheet entity Office of the Comptroller of the Currency Office of Thrift Supervision other-than-temporarily impaired private-label MBS Securities and Exchange Commission Structured... to shift the ‘‘deregulation’’ narrative toward other targets: first, the failure to regulate the practices of subprime mortgage originators, and second, the failure to regulate ‘ the derivatives market.’’ The trio of deregulatory (GLBA) and nonregulatory actions (nonregulation of subprime lending and of derivatives) fingered by Leonhardt remain, as we write, the three primary meanings of ‘‘deregulation’’... instead, the set of regulations governing banks’ capital levels known as the Basel rules When we began researching the financial crisis in the early months of 2009, we were driven by our dissatisfaction with the analyses then on offer At the time, there were (understandably) only hypotheses that lacked evidence, and many of them, while equally plausible, contradicted each other Additionally, there were... that they ‘‘went crazy.’’ Our criticisms of the conventional wisdom may seem unfair Journalists first popularized many of the dominant claims about the crisis, and under the pressure of 01-ffirs.qxd 7/4/04 8:24 PM Page i AUDITOR’S DICTIONARY Terms, Concepts, Processes, and Regulations David O’Regan John Wiley & Sons Inc 01-ffirs.qxd 7/4/04 8:24 PM Page iv 01-ffirs.qxd 7/4/04 8:24 PM Page i AUDITOR’S DICTIONARY Terms, Concepts, Processes, and Regulations David O’Regan John Wiley & Sons Inc 01-ffirs.qxd 7/4/04 8:24 PM Page ii This book is printed on acid-free paper ∞ Copyright © 2004 by John Wiley & Sons All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be 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Data: O’Regan, David Auditor’s dictionary : terms, concepts, processes, and regulations / David O’Regan p cm ISBN 0-471-53118-9 (cloth) Auditing—Dictionaries I Title HF5667.O6728 2004 657'.03 — dc22 2004003665 Printed in the United States of America 10 01-ffirs.qxd 7/4/04 8:24 PM Page iii To Abhishikta and my parents 01-ffirs.qxd 7/4/04 8:24 PM Page iv 01-ffirs.qxd 7/4/04 8:24 PM Page v Acknowledgments When this dictionary was under preparation a great deal of assistance, generosity, and razor-sharp comment came my way I wish to acknowledge my gratitude to all those who helped me by answering queries, giving opinions, drawing attention to valuable sources, and supplying information and documents from private collections All of this led to a better book I thank the following (with apologies for the inadvertent omission of any academic or professional titles): Lynne Alexander, Chris Allen, Rachel Alterator, Professor Urton Anderson, John Marnie Angeles, Dolores Argo, Susannah Bolton, Barbara Brady, Fergus Brown, Geordie Cassin, Professor Andrew Chambers, Chiba Kanan, Danielle Cohen, Dr Robert Colson, Charlie Culkin, Shirley Davies, Stefan de Greling, Wendeline Dill, Aslam Dossa, Sheila Doyle, Kim Ellis, Professor Serge Evraert, Michael Feland, Professor Dale L ... ([link]) 5/9 Digestive System Processes and Regulation Digestive Processes The digestive processes are ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and defecation Some... food with digestive juices Peristalsis is so powerful that foods and liquids you swallow enter your stomach even if you are standing on your head 3/9 Digestive System Processes and Regulation. .. enzymatic activity 2/9 Digestive System Processes and Regulation Functions of the Digestive Organs Organ Major functions Other functions • Pancreas: produces digestive enzymes and bicarbonate Large