Ten output devices, advantages and disadvantages, inter-site back-up mechanism, Expert systems for medical diagnosis,information systems security

(i)Printer

Printer enables us to produce information output on paper. It is one of the most popular computer output devices we often use to get information on paper - called hard copy.

Advantage

They produce high quality paper output for presentation at a speedy rate.

It is also possible to share the printer among different users in a network.

Disadvantage

The cost for maintenance of the printer equipment as well printing ink is cumulatively high.

(ii) Plotters

These devices are used to produce graphical outputs on paper. They have automated pens that make line drawings on paper

Advantage

They can produce neat drawings on a piece of paper based on user commands. In Computer Aided Design (CAD) they are used to produce paper prototypes that aid in design of the final system.

Disadvantage

They are more expensive than printers.

Further, the command based interface is difficult to use.

(iii)Monitor

It is the screen that is used to display soft copy output to users. It the most common output devices for a computer

Advantage

Most computing devices come with an inbuilt display unit (monitors)

Disadvantage

The older versions which used CRT technology consume a lot of power while others produce harmful radiations that can be injurious to long term users.

(iv) Projector

This is a computer output device that projects a video signal on to a surface

Advantage

It can project output to a larger audience as compared to the limited display size of a monitor.

Disadvantage

They require to be used in dark rooms for clarity to be achieved

(v) Braille embosser

This is a device capable of producing Braille output for the visually impaired.

Advantage

It offers an effective output alternative for the visually impaired hence improving their ease of access to computer outputs.

Disadvantage

It is fully dedicated to the visually impaired and can therefore not be used for any other users.

(vi) Speakers

This are output devices either connected externally or inbuilt to transmit audio outputs from a computing device.

Advantage

They are easy to operate as no additional functions are required to play sound through them(plug and play)

Disadvantage

They may distract other people from their work and hence not favorable for work environment especially where offices are shared.

(vii)Holograms

Holograms are advanced technologies  used to generate 3D outputs

Advantage

Can produce 3D graphics which are hard to generate on other output devices

Disadvantage

The equipment required to achieve this function is highly complex and difficult to operate.

(viii) Electronic paper

These are devices designed to mimic the appearance of ordinary ink on paper on a computer

Advantage

Electronic paper displays reflect light like ordinary paper, theoretically making it more comfortable to read, and giving the surface a wider viewing angle compared to conventional displays.

Disadvantage

They result to more power consumption and are expensive to acquire.

(ix) Fax Machine

Advantage

Using a fax machine is much faster than sending an item through the Postal Service.

Disadvantage

If there is a network outage for either of these the fax machine is compromised.

(x)Heptatic displays

These are smaller display screens used in hand held devices and most mobile computing devices e.g touch screens.

Advantage
They are easy to use for smaller devices

Disadvantage

They offer low resolution and have a limited display screen.

inter-site back-up mechanism 

Virtual Office Space

  The distributed sites cooperate in an inter-site back-up mechanism to provide for system recovery from a variety of failures within the system. Failure recovery is both automatic and timely through cooperation among sites. Back-up sites associated with a given primary site are identified. 
 

The non-transitory computer-readable storage medium

 Involves using the inter-site back-up mechanism comprising:

 identifying a primary site from the plurality of distributed sites; and selecting a plurality of back-up sites from the plurality of distributed sites to provide failure recovery for the identified primary site.

Using Checkpoints

When a system fails, the log is consulted to determine those transactions that need to be redone and those that need to be undone. A search of the entire log is performed to determine this information. Checkpoints are introduced to reduce the overheads i.e. search process is time consuming. The following is the sequence of actions in checkpoints

Using Shadow paging

When a transaction starts the two pages are same, the shadow page table is never changed thereafter and is used to restore the database in the event of a system failure. This comes in handy when overcoming the overhead in the log file based recovery and it is faster.

Using logs

Whenever a transaction performs a write, it is essential that the log record for that write be created before the database is modified. In order for log records to be used for recovery the log must reside in stable storage.

In the event of system failure the database can be correctly recovered using these logs.

Expert systems for medical diagnosis

Expert systems for medical diagnosis are necessary because of the influx of new information which is so massive that these expert systems must be specialized. The processes can be broken down as below:

The doctor is simulated by a large medical database.

 An inquiry consists of symptoms and signs and lab results.

This is matched against known conditions and a short list is produced (the database is so large this is rarely a short "short list" but there are options to focus the resultant short list).

The matching is performed using a number of mathematical like "expert system" functions. Thus say we have the inquiry "facial paralysis, poor horizontal gaze, tingling sensations in left side of the body".

The expert system modules use various combinations in an attempt to find the disease pattern that best satisfies the inquiry.

How common a disorder is enters the equation.

History can enter the equation.

Lab results can enter the equation (however, there is a function just for lab results).

 Physicians who use it tend to comment that the software is a memory aid usually listing a huge number of potential conditions in response to an inquiry.

Despite these advances, further major research and developmental efforts will be necessary before expert performance by the computer becomes a reality.

information systems security

Involves protecting information and information systems from unauthorized access, use, disclosure, disruption, modification, or destruction..

The first action of a management program to implement information security is to have a security program in place. The objectives include:

• Protect the company and its assets.
• Manage Risks by Identifying assets, discovering threats and estimating the risk
• Provide direction for security activities by framing of information security policies, procedures, standards, guidelines and baselines
• Information Classification
• Security Organization and
• Security Education

Security Controls

Security Controls can be classified into three categories

Administrative Controls which include

• Developing and publishing of policies, standards, procedures, and guidelines.
• Screening of personnel.
• Conducting security-awareness training and
• Implementing change control procedures.

Technical or Logical Controls which include

• Implementing and maintaining access control mechanisms.
• Password and resource management.
• Identification and authentication methods
• Security devices and
• Configuration of the infrastructure.

Physical Controls which include

• Controlling individual access into the facility and different departments
• Locking systems and removing unnecessary floppy or CD-ROM drives
• Protecting the perimeter of the facility
• Monitoring for intrusion and
• Environmental controls.

References

Daniel Mellado, David G. Rosado (2012) An Overview of Current Information Systems Security Challenges and Innovations. Journal of Universal Computer Science.

Thomas C, Carolyn B (2005). Database Systems 4^th Edition “A practical approach to design, implementation and management” (p. 614). Addison Wesley