Masters Theses in the Pure and Applied Sciences: Accepted by Colleges and Universities of the United States and Canada Volume 39

426 Pages·1996·12.05 MB·English

by  Wade H. Shafer (auth.), Wade H. Shafer (eds.)

MASTERS THESES IN THE
PURE AND APPLIED SCIENCES
ACCEPTED BY COLLEGES AND UNIVERSITIES
OF THE UNITED STATES AND CANADA
VOLUME 39
MASTERS THESES IN THE
PURE AND APPLIED SCIENCES
ACCEPTED BY COLLEGES AND UNIVERSITIES
OF THE UNITED STATES AND CANADA
VOLUME 39
Edited by
Wade H. Shafer
Center for Information and Numerical Data Analysis and Synthesis
PLENUM PRESS • NEW YORK AND LONDON
The Library of Congress cataloged the first volume of this title as follows:
Masters theses in the pure and applied sciences accepted by colleges and univer
sities of the United States. v. [1)-1955-56 -
Lafayette, Ind., School of Mechanical Engineering, Purdue University.
v. 29 cm.
Title varies: 1955-56 - 1957, Master's theses accepted by U.S. colleges and
universities in the fields of chemical engineering, chemistry, mechanical engineering,
metallurgical engineering, and physics.-1958, Master's theses and doctoral dis
sertations in the pure and applied sciences accepted by colleges and universities
of the United States.
Vols. for 1955-56- issued by Purdue University's Thermophysical Properties
Research Center (1955-56 as its TPRC publication)
QC251.P8
1. Science-Bibl. 2. Engineering--Bibl. 3. Dissertations, Academic-U.S.--Bibl.
I. Purdue University, Lafayette, Ind. Thermophysical Properties Research Center.
(Series: Purdue University, Lafayette, Ind. Thermophysical Properties Research
Center. TPRC publication)
Z7401.M35 58-62673
Library of Congress Catalog Card Number 58-62673
ISBN-13: 978-1-4613-8032-0 e-ISBN-13: 978-1-4613-0393-0
001:10.1007/978-1-4613-0393-0
© 1996 Plenum Press, New York
Softcover reprint of the hardcover 1s t edition 1996
A Division of Plenum Publishing Corporation
233 Spring Street, New York, N.Y. 10013
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
PREFACE
Masters Theses in the Pure and Applied Sciences was first conceived, published,
and disseminated by the Center for Information and Numerical Data Analysis and
Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses
with the academic year 1955. Beginning with Volume 13, the printing and dis
semination phases of the activity were transferred to University Microfilms/Xerox
of Ann Arbor, Michigan, with the thought that such an arrangement would be
more beneficial to the academic and general scientific and technical community.
After five years of this joint undertaking we had concluded that it was in the
interest of all concerned if the printing and distribution of the volumes were
handled by an international publishing house to assure improved service and
broader dissemination.
Hence, starting with Volume 18, Masters Theses in the Pure and Applied
Sciences has been disseminated on a worldwide basis by Plenum Publishing
Corporation of New York, and in the same year the coverage was broadened to
include Canadian universities. All back issues can also be ordered from Plenum.
We have reported in Volume 39 (thesis year 1994) a total of 13,953 thesis titles
from 21 Canadian and 159 United States universities. We are sure that this
broader base for these titles reported will greatly enhance the value of this impor
tant annual reference work.
While Volume 39 reports theses submitted in 1994, on occasion, certain uni
versities do report theses submitted in previous years but not reported at the time.
This fact is indicated for each thesis citation by the thesis year shown in paren
theses.
The organization of Volume 39 is identical to that of past years. It consists of
theses titles arranged by discipline and by university within each discipline. Any
accredited university or college with a graduate program in the pure and applied
sciences (excluding mathematics and the life sciences) is invited to contribute
titles in the fields presently covered. Inquiries concerning interlibrary loan or pur
chase of any title mentioned in this volume should be sent directly to the institu
tion responsible for the thesis.
Some theses may be shifted in their listing to best reflect their contents with
respect to the 44 different study disciplines. For example, a thesis in civil engi
neering may be listed in this publication under disciplines 09-Civil Engineering,
23-lrrigation Engineering, 42-Sanitary Engineering, Water Pollution, and Water
Resources, or 44-Transportation Engineering.
The editor gratefully acknowledges the cooperation of the librarians and gradu
ate school officials whose continued interest in this work makes its publication
possible. Also, CINDAS has played a key part in the publication of this reference
work since thesis year 1955.
"Formerly the Thermophysical Properties Research Center (TPRC)
CONTENTS
Preface ................... . .v
Comparative Data on the Series ..... . viii
Participating Universities . . . . . . . . . . . . xi
Masters Theses Listed by Study Discipline*
1. Aerospace Engineering .. . . . . . . . . 1
2. Agricultural Economics, Sciences and Engineering 11
3. Architectural Engineering and Urban Planning . 39
4. Astronomy . . . . . . 48
5. Astrophysics . . . . . . . . . 49
6 Ceramic Engineering. . . . . 50
7. Chemical Engineering . . . . 52
8. Chemistry and Biochemistry . 69
9. Civil Engineering . . . . . . . 95
10. Communications Engineering and Computer Science . 116
11. Cryogenic Engineering . 148
12. Electrical Engineering . 149
13. Engineering Mechanics ....... . 199
14. Engineering Physics . . . . . . . . . . 202
15. Engineering Science . . . . . . . . . . 204
16. Fuels, Combustion and Air Pollution . 217
17. General and Environmental Engineering 218
18. Geochemistry and Soil Science . . . .. ... 237
19. Geological Sciences and Geophysical Engineering 242
20. Geology and Earth Science ........... . 245
21. Geophysics . . . . . . . . . . . . . . . . . . . . . 261
22. Industrial Engineering and Operations Research 264
23. Irrigation Engineering ............ . . None
24. Marine and Ocean Engineering . . . . . . . . 278
25. Materials Science and Engineering . . . . . . 281
26. Mechanical Engineering and Bioengineering . 291
27. Metallurgy ............... . 339
28. Meteorology and Atmospheric Science . . 342
29. Mineralogy and Petrology . . . . . . . . . 347
30. Mining and Metallurgical Engineering. . . 348
31. Missile and Space Systems Engineering. 351
32. Nuclear Engineering . . . . . . . . . 355
33. Nuclear Physics . . . . . . . . . . . . . . 358
34. Nuclear Science . . . . . . . . . . . . . . . None
35. Oceanography and Marine Science ... 359
36. Petroleum and Natural Gas Engineering . 363
37. Photogrammetric and Geodetic Engineering 366
38. Physics and Biophysics . . . . . . . . . . . 367
39. Plastics Engineering ............ . 380
40. Wood Technology, Forestry and Forest Science 382
41. Reactor Science . . . . . . . . . . . . . . . . . . 389
42. Sanitary Engineering, Water Pollution and Resources 390
43. Textile Technology .................. . 399
44. Transportation Engineering .... . . . . . . . . . . . 401
Theses without Specification of School or Department .. 410
"Mathematics and most life sciences have been excluded from this publication, on a purely arbitrary
basis, simply to limit the scope of the work. Biochemistry, biophysics, and bioengineering are in
cluded in the coverage when titles in these areas are reported together with chemistry, physics,
and engineering and not as a separate discipline.
COMPARATIVE DATA ON THE SERIES
Thesis Contributing Titles
Volume Publication Date Year Institutions Reported
Oct. 1957 1955 93 1,002
1956 93 1,027
2 Aug. 1958 1957 154 1,727
3 Oct. 1959 1958 139 3,736
4 Dec. 1960 1959 162 4,984
5 Dec. 1961 1960 183 5,708
6 Dec. 1966 1961 186 5,911
7 Aug. 1966 1962 186 6,321
8 Aug. 1966 1963 175 6,505
9 Jan. 1968 1964 174 6,940
10 Jan 1968 1965 170 7,310
11 Jan. 1968 1966 173 7,099
12 Jul. 1968 1967 167 6,909
13 Jul. 1969 1968 174 7,802
14 Jan. 1971 1969 175 7,160
15 Jul. 1971 1970 183 7,437
16 Jul. 1972 1971 182 7,170
17 Jul. 1973 1972 250 8,513
18t Dec. 1974 1973 251 10,381
19 Dec. 1975 1974 229 10,045
20 Dec. 1976 1975 267 10,374
21 Dec. 1977 1976 244 10,586
22 Oct. 1978 1977 255 10,658
23 Nov. 1979 1978 247 10,432
24 Nov. 1980 1979 241 10,033
25 Dec. 1981 1980 241 10,308
26 Dec. 1982 1981 242 11,048
27 Dec. 1983 1982 227 10,918
28 Dec. 1984 1983 223 10,611
29 Dec. 1985 1984 225 12,637
30 Aug. 1987 1985 212 12,400
31 Aug. 1988 1986 206 11,480
32 Dec. 1989 1987 198 12,483
33 Jul. 1990 1988 208 13,273
34 Mar. 1992 1989 210 13,377
35 Oct. 1992 1990 200 12,026
36 Mar. 1993 1991 184 11,024
37 Nov. 1993 1992 178 12,549
38 Dec. 1994 1993 186 13,787
39 Mar. 1996 1994 180 13,953
'Part Two of Volume 3 included doctoral dissertations from the 1956-1957 academic year, citing
2,846 titles from 103 universities.
tEffective with Volume 18, the coverage was extended to include Canadian universities.
PARTICIPATING UNIVERSITIES
PARTICIPATING UNIVERSITIES xi
1. ACADIA UNIVERSITY 26. CARLETON UNIVERSITY
WOLFVILLE, NOVA SCOTIA OITAWA,CANADAK1S5B6
CANADA BOP IXO
27. CARNEGIE-MELLON UNIVERSITY
2. AKRON, UNIVERSITY OF PITTSBURG, PENNSYLVANIA 15213
AKRON, omo 44304
28. CASE WESTERN RESERVE UNIVERSITY
3. ALABAMA A -M UNIVERSITY CLEVELAND, omo 44106
NORMAL, ALABAMA 35762
29. CENTRAL FLORIDA, UNIVERSITY OF
4. ALABAMA, UNIVERSITY OF ORLANDO, FLORIDA 32816-0450
HUNTSVILLE, ALABAMA 35899
30. CITY COLLEGE OF NEW YORK
5. ALABAMA, UNIVERSITY OF NEW YORK, NEW YORK 10031
BIRMINGHAM, ALABAMA 35294
31. CLARK ATLANTA UNIVERSITY
6. ALBERTA, UNIVERSITY OF ATLANTA, GEORGIA 30314
EDMONTON, ALBERTA
CANADA T6G 2E8 32. CLARKSON COLLEGE OF TECHNOLOGY
POTSDAM, NEW YORK 13676
7. ALFRED UNIVERSITY
ALFRED, NEW YORK 14802 33. CLEMSON UNIVERSITY
CLEMSON, SOUTH CAROUNA 2%31
8. AMERlCANUNIVERSITY
WASHINGTON, D.C. 20016 34. CLEVELAND STATE UNlVERSITY
CLEVELAND, omo 44115
9. ARKANSAS, UNIVERSITY OF
FAY ETIESVILLE, ARKANSAS 72701 35. COLORADO SCHOOL OF MINES
GOLDEN, COLORADO 80401
10. AUBURN UNIVERSITY
AUBURN, ALABAMA 36849 36. COLORADO STATE UNIVERSITY
FORT COLUNS, COLORADO 80523
11. BALL STATE UNIVERSITY
MUNCIE, INDlANA 47306-0160 37. CONCORDIA UNIVERSITY
MONTREAL, QUEBEC,
12. BOSTON COLLEGE CANADA H3G 1MB
CHESTNUT HlLL, MASSACHUSETTS 02167
38. DALHOUSIE UNIVERSITY
13. BRlGHAM YOUNG UNIVERSITY HALIFAX, NOVA SCOTIA
PROVO, UTAH 84602 CANADA B3H 4H6
14. BROCK UNlVERSITY 39. DE PAUL UNIVERSITY
ST. CATHARINES,ONTARlO CmCAGOZ ILLINOIS 60614-3214
CANADA L2S 3A1
40. DELAW ARE, UNIVERSITY OF
15. BROOKLYN COLLEGE NEWARK, DELAWARE 19711
BROOKLYN, NEW YORK 11210
41. DREXEL UNIVERSITY
16. BROWN UNIVERSITY PHlLADELPmA,PENNSYLVANIA 19104
PROVIDENCE, RHODE ISLAND 02912
42. DUKE UNlVERSITY
17. BUCKNELL UNIVERSITY DURHAM, NORTH CAROUNA 27706
LEWISBURG, PENNSYLVANIA 17837
43. DUQUESNE UNIVERSITY
18. CALGARY, UNIVERSITY OF PITTSBURGH, PENNSYLVANIA 15219
CALGARY, ALBERTA, CANADA T2N 1N4
44. EAST CAROUNA UNIVERSITY
19. CALIFORNIA STATE UNIVERSITY GREENVILLE, NORTH CAROUNA 27834
LONG BEACH, CAUFORNIA 90840
45. EAST TENNESSEE STATE UNIVERSITY
20. CALIFORNIA STATE UNIVERSITY JOHNSON CITY, TENNESSEE 37614-0002
FRESNO, CAUFORNIA 93740-0034
46. EASTERN ILLINOIS UNIVERSITY
21. CALIFORNIASTATEUNIVERSITY CHARLESTON, ILLINOIS 61920
SACRAMENTO, CALIFORNIA 95819-2695
47. EASTERNKENTUCKYUNIVERSITY
22. CALIFORNIA STATE UNIVERSITY RlCHMOND, KENTUCKY 40475-3101
FULLERTON, CALIFORNIA 92634-4080
48. EASTERN NEW MEXICO UNIVERSITY
23. CALIFORNIA, UNIVERSITY OF PORTALES, NEW MEXICO 88130
IRW!NE, CALIFORNIA 92717
49. EASTERN WASHINGTON UNlVERSITY
24. CALIFORNIA, UNIVERSITY OF CHENEYZ WASHINGTON 99004
DAVIS, CALIFORNIA 95616
SO. FLORIDA ATLANTIC UNIVERSITY
25. CALIFORNIA, UNIVERSITY OF BOCA RATON, FLORIDA 33431-0991
LA JOLLA, CALIFORNIA 92093
51. FLORIDA STATE UNIVERSITY
TALLAHASSEE, FLORIDA 32306
xii PARTICIPATING UNIVERSITIES (continued)
52. FLORIDA, UNIVERSITY OF 78. LOYOLA UNIVERSITY
GAINESVILLE, FLORIDA 32611 CHICAGO, ILLINOIS 60611
53. FORT HAYS STATE UNIVERSITY 79. MANITOBA, UNIVERSITY OF
HAYS, KANSAS 67601-4099 WINNIPEG, MANITOBA
CANADA R3T 2N2
54. GEORGIA INSTI11JTE OF TECHNOLOGY
ATLANTA, GEORGIA 30332 80. MARQUETTE UNIVERSITY
MILWAUKEE, WISCONSIN 53233
55. GUAM, UNIVERSITY OF
GUAM 96923 81. MARSHALL UNIVERSITY
HUNTINGTON, WEST VIRGINIA 25755-2100
56. GUELPH, UNIVERSITY OF
GUELPH, ONTARIO, CANADA NIG 2WI 82. MASSACHUSETTS INSTI11JTE OF
TECHNOLOGY
57. HOUSTON, UNIVERSITY OF CAMBRIDGE, MASSACHUSETTS 02139
HOUSTON, TEXAS 77004
83. MASSACHUSETTS, UNIVERSITY OF
58. HOWARD UNIVERSITY AMHERST, MASSACHUSETTS 010003
WASHINGTON, D.C. 20059
84. MC MASTER UNIVERSITY
59. IDAHO STATE UNIVERSITY HAMILTON ONTARIOZ CANADA L8S 4K8
POCATELLO, IDAHO 83209-0009
85. MC NEESE STATE UNIVERSITY
60. IDAHO, UNIVERSITY OF LAKE CHARLES, LOUISIANA 70609-2180
MOSCOW, IDAHO 83843
86. MIAMI, UNIVERSITY OF
61. ILLINOIS STATE UNIVERSITY CORAL GABLES, FLORIDA 33124
NORMAL, ILLINOIS 61761-6901
87. MICHIGAN TECHNOLOGICAL UNIVERSITY
62. INDIANA STATE UNIVERSITY HOUGHTON, MICHIGAN 49931
TERRE HAUTE, INDIANA 47809
88. MINNESOTA, UNIVERSITY OF
63. INDIANA UNIVERSITY MINNEAPOLIS, MINNESOTA 55455
BLOOMINGTON, INDIANA 47405
89. MISSISSIPPI, UNIVERSITY OF
64. INDIANA UNIVERSITY OF PENNSYLVANIA UNIVERSITY, MISSISSIPPI 38677
INDIANA, PENNSYLVANIA 15705-1087
90. MISSOURI, UNIVERSITY OF
65. IOWA STATE UNIVERSITY ROLLA, MISSOURI 65401
AMES, IOWA 50011-2140
91. MONTANA COLLEGE OF MINERAL
66. JOHN CARROLL UNIVERSITY SCIENCE AND TECHNOLOGY
CLEVELAND, OHIO 44118 BUTTE, MONTANA 59701
67. JOHNS HOPKINS UNIVERSITY 92. MONTANA STATE UNIVERSITY
BALTIMORE, MARYLAND 21218 BOZEMAN, MONTANA 59717-0022
68. KANSAS STATE UNIVERSITY 93. MONTANA, UNIVERSITY OF
MANHAT TA NZ KANSAS 66506-1103 MISSOULA, MONTANA 59812
69. KANSAS, UNIVERSITY OF 94. MONTREAL, UNIVERSITY OF
LAWRENCE, KANSAS 66045-2800 MONTREAL, QUEBEC
CANADA H3C 3J7
70. KENTUCKY, UNIVERSITY OF
LEXINGTON, KENTUCKY 40506 95. MURRAY STATE UNIVERSITY
MURRAY, KENTUCKY 42071-3308
71. LAKE HEAD UNIVERSITY
THUNDER BAY, ONTARIO, 96. NEBRASKA, UNIVERSITY OF
CANADA P7B 5EI LINCOLN, NEBRASKA 68588-0410
72. LAMAR UNIVERSITY 97. NEW BRUNSWICK, UNIVERSITY OF
BEAUMONT, TEXAS 77710 FREDERICTON, NEW BRUNSWICK
CANADA E3B 5H5
73. LAURENTIEN UNIVERSITY
SUDBURY, ONTARIO 98. NEW JERSEY INSTITUTE OF TECHNOLOGY
CANADA P3E 2C6 NEWARK, NEW JERSEY 07102
74. LEHIGH UNIVERSITY 99. NEW MEXICO STATE UNIVERSITY
BETHLEHEM,PENNSYLVANIA 18015 LAS CRUCES, NEW MEXICO 88003-0006
75. LONG ISLAND UNIVERSITY 100. NEW MEXICO, UNIVERSITY OF
BROOKLYN, NEW YORK 11201-5372 ALBUQUERQUE. NEW MEXICO 87131
76. LOUISVILLE, UNIVERSITY OF 101. NEW YORK, STATE UNIVERSITY OF
LOUISVILLE, KENTUCKY 40292 BUFFALO, NEW YORK 14260
77. LOWELL, UNIVERSITY OF 102. NEW YORK, STATE UNIVERSITY OF
LOWELL, MASSACHUSETTS 01854 FREDONIA, NEW YORK 14063
PARTICIPATING UNIVERSITIES (continued) xiii
103. NEW YORK, STATE UNIVERSITY OF 128. ROSE-HULMAN INSTITUTE OF
ALBANY, NEW YORK 12222 TECHNOLGY
TERRE HAUTE, INDIANA 47803-3999
104. NIAGARA UNIVERSITY
NIAGARA, NEW YORK 14109 129. SAINT LOUIS UNIVERSITY
SAINT LOUIS, MISSOURI 63108
105. NORTH CAROLINA STATE UNIVERSITY
RALEIGH, NORTH CAROLINA 27695-7102 130. SAN JOSE STATE UNIVERSITY
SAN JOSE, CALIFORNIA 95192
106. NORTH CAROLINA, UNIVERSITY OF
CHAPEL HILL, NORTH CAROLINA 27599-3922 131. SHERBROOKE, UNIVERSITY OF
SHERBROOKE, QUEBEC,
107. NORTH DAKOTA STATE UNIVERSITY CANADA JIK 2RI
FARGO, NORTH DAKOTA 58105-5599
132. SOUTH CAROLINA, UNIVERSITY OF
108. NORTH DAKOTA, UNIVERSITY OF COLUMBIA, SOUTH CAROLINA 29208
GRAND FORKS, NORTH DAKOTA 58202
133. SOUTH DAKOTA STATE UNIVERSITY
109. NORTH TEXAS, UNIVERSITY OF BROOKINGS, SOUTH DAKOTA 57007-1098
DENTON, TEXAS 76203
134. SOUTH FLORIDA, UNIVERSITY OF
110. NORTHERN ARIZONA UNIVERSITY TAMPA, FLORIDA 33620-5350
FLAGSTAFF, ARIZONA 86011
135. SOUTHERN ILLINOIS UNIVERSITY
111. NORTHERN ILLINOIS UNIVERSITY EDWARDSVILLE, ILLINOIS 62026-1046
DEKALB, ILLINOIS 60115-2854
136. SOUTHERN METHODIST UNIVERSITY
112. NORTHERN IOWA, UNIVERSITY OF DALLAS, TEXAS 75275
CEDAR FALLS, lOW A 50613
137. SOUTHWEST TEXAS STATE UNIVERSITY
113. OKLAHOMA STATE UNIVERSITY SAN MARCOS, TEXAS 78666-4604
STILLWATER, OKLAHOMA 74074
138. SOUTHWESTERN LOUISIANA, UNIV. OF
114. OKLAHOMA, UNIVERSITY OF LAFAYETTE, LOUISIANA 70503-2038
NORMAN, OKLAHOMA 73069
139. STEPHAN F. AUSTIN STATE UNIVERSITY
115. OLD DOMINION UNIVERSITY NACOGDOCHES, TEXAS 75962-3024
NORFOLK, VIRGINIA 23508-8506
140. STEVENS INSTITUTE OFTECHNOLOGY
116. OREGON, UNIVERSITY OF HOBOKEN, NEW JERSEY 07030
EUGENE, OREGON 97403-1219
141. TEMPLE UNIVERSITY
117. PENNSYLVANIA STATE UNIVERSITY PHILADELPHIA, PENNSYLV ANlA 19122
UNIVERSITY PARK, PENNSYLVANIA
16802 142. TENNESSEE TECHNOLOGICAL
UNIVERSITY
118. PITTSBURGH, UNIVERSITY OF COOKEVILLE, TENNESSEE 38501
PITTSBURGH, PENNSYLVANIA 15261
143. TENNESSEE, UNIVERSITY OF
119. POLYTECHNIC UNIVERSITY TULLAHOMA, TENNESSEE 37388
BROOKLYN, NEW YORK 11201
144. TEXAS A AND M UNIVERSITY
120. PUERTO RICO, UNIVERSITY OF COLLEGE STATION, TEXAS 77843
RIO PIEDRAS, PUERTO RICO 00931-3346
145. TEXAS CHRISTIAN UNIVERSITY
121. PURDUE UNIVERSITY FORT WORTH, TEXAS 76129
WEST LAFAYETTE, INDIANA 47907
146. TEXAS SOUTHERN UNIVERSITY
122. QUEENS COLLEGE HOUSTON, TEXAS 77004-4814
FLUSHING, NEW YORK 11367
147. TEXAS TECH UNIVERSITY
123. QUEENS UNIVERSITY LUBBOCK, TEXAS 79409
KINGSTON, ONTARIO
CANADA K7L 3N6 148. TEXAS WOMEN S UNIVERSITY
DENTON, TEXAS 76204
124. REGINA, UNIVERSITY OF
REGINA, CANADA S4S OA2 149. TEXAS, UNIVERSITY OF
AUSTIN, TEXAS 78713-7330
125. RENSSELAER POLYTECHNIC INSTITUTE
TROY, NEW YORK 12180-3590 150. TEXAS, UNIVERSITY OF
ARLINGTON, TEXAS 76019
126. RHODE ISLAND, UNIVERSITY OF
KINGSTON, RHODE ISLAND 02881-0803 151. TOLEDO, UNIVERSITY OF
TOLEDO, OHIO 43606
127. ROCHESTER, UNIVERSITY OF
ROCHESTER, NEW YORK 14627 152. TORONTO, UNIVERSITY OF
TORONTO, ONTARIO
CANADAM5S 1M