Difference between revisions of "Step 3.8"

Revision as of 11:19, 21 March 2013

STEP 3.8 : MESH MATCHING

MARS 2.0 can match bibliographic headings against headings in the National Library of Medicine Medical Subjects Authority File (hereafter referred to as MESH). The current Medical authority file contains just over 615,000 authority records for descriptors, qualifiers, and descriptor/qualifier combinations.

fields matched

The following fields are matched against MESH:

Note: Only those with a 2nd indicator of 2 are MESH

ignore or remove without processing

Some libraries have catalogs that do not contain subject headings coded as MESH. Other libraries have bibliographic records in their catalog that contain MESH, but their local system is profiled to exclude them from the OPAC indexes.

Most libraries in which the MESH are not used and are not causing any problems for patrons choose to ignore these headings.

Alternatively, you can choose to remove without processing any MESH that MARS 2.0 encounters during processing.

DATABASES AND SEARCH ORDER

If you choose to have your MESH processed, you also have the choice of which database to search against as well as in which order the databases should be searched. The two databases available to search are:

• MESH Authority File
• LC Authority File

search mesh authority file only

In this option, MARS 2.0 matches MESH against MESH only. For those headings that match a heading in MESH, the indicator remains as 2.

Headings that match a cross-reference in MESH are flipped to the established form of the heading and the 2nd indicator is again retained as a 2.

After the matching is completed, all remaining MESH (i.e., those that did not match a heading in MESH) are retained in the records.

search mesh against lc only

In the catalogs at some libraries, the presence of MESH in their bibliographic records creates duplicate and sometimes confusing index entries for patrons. These libraries may wish to consider choosing this option:



In this option, MARS 2.0 first matches the MESH against the LC Authority File as if the headings had a 2nd indicator of 0 instead of 2.

For those headings that match a heading in LC, the indicator is changed from 2 to 0. Headings that match a cross-reference in LC are flipped to the established form of the heading and the 2nd indicator is again changed from 2 to 0.

After the matching is completed, all remaining MESH (i.e., those that did not match a heading in an LC authority record) are removed from the records.

Or, you could choose that any MESH that fail to match an LC authority record are retained in the bibliographic record with the original 2nd indicator value of 2.

 
 original bib medical heading:
 650  2 $a Neoplasms.
 
 MARS 2.0 compares the heading against the LC Subjects file.
 The heading would match a cross-reference (4XX) in LC sh 850138553:
 150    $a Tumors
 450    $a Neoplasms
 
 updated bib medical heading:
 650  0 $a Tumors.
 

When subject headings are converted from MESH to LC, MESH subdivisions that are not part of the matching LC authority are retained in their original form. For example, the heading below does not have an LC record for the full MESH:

 
 650  2 $a Neoplasms $x diagnosis.
 

The main part of the heading $a would match on the same LC authority listed above. A higher-level conversion would occur in which the $a is converted to LC, while $x is retained in its original form:

 
 650  0 $a Tumors $x diagnosis.

search mesh 1st, lc 2nd

Some libraries prefer to search their MESH against the MESH Authority File first. Any matches found will update the heading, but the 2nd indicator value will remain as 2.

However, unmatched MESH could then be searched against LC. Any matches found during this procedure would change the value of the 2nd indicator from 2 to 0:



In this option, MARS 2.0 processes would retain unmatched MESH, with a 2nd indicator value of 2, to be searched at a later date by the library (of course, remove unmatched could instead be chosen above if the library preferred that option).

Matched headings for this option could either have a 2nd indicator value of 2 for matches found within MESH or a 2nd indicator value of 0 for matches found within LC.

Changing the search order (LC=1, MESH=2) reverses the order in which headings are matched:

 
 original bib medical heading:
 610 22 $a Johns Hopkins University. $b School of Medicine. $b Division of Medical Genetics.
 
 matches LC n 85363832:
 110 2  $a Johns Hopkins University. $b Division of Medical Genetics.
 410 2  $a Johns Hopkins University. $b School of Medicine. $b Division of Medical Genetics.
 
 updated bib MESH:
 610 20 $a Johns Hopkins University. $b Division of Medical Genetics.
 

RETAIN OR SPLIT MEDICAL SUBDIVISION FORMS

MARS 2.0 offers you the option of retaining your MESH subdivision forms as they exist within the heading, or to split them out into a separate field: topical (650), geographic (651), or form (655):

 
 original MESH bib heading:
 650  2 $a Ethics, Medical $x legislation
 
 updated MESH bib headings:
 650  0 $a Ethics, Medical
 655  7 $a Legislation $2 mesh
 

Currently the National Library of Medicine uses this faceted approach in LocatorPlus but combines all headings and subheadings into one string in their bibliographic utilities.

faceted medical subdivision forms

MESH AUTHORITY CONTROL NUMBERS

MESH authority records carry the control number in field 001. However, some systems use the 010 field as the only control number, or include the 010 field in a system control number index:

 
 MESH control number in 001 field only:
 001    D0206980D0009
 150 $a Duodenoscopes $x adverse effects
 
 MESH control number in 001 and 010 fields:
 001    D0206980D0009
 010 $a D0206980D0009
 150 $a Duodenoscopes $x adverse effects

LINKS