The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3D SYSTEMS CORP COM 88554D205 110,113 2,508,278 SH   SOLE   2,508,278 0 0
3M CO COM 88579Y101 478 4,367 SH   SOLE   4,367 0 0
ABBOTT LABORATORIES COM 002824100 706 20,247 SH   SOLE   20,247 0 0
ABBVIE INC COM 00287Y109 825 19,947 SH   SOLE   19,947 0 0
ACTUANT CORP A COM 00508X203 2,488 75,472 SH   SOLE   75,472 0 0
ALTERA CORP COM 021441100 376 11,408 SH   SOLE   11,408 0 0
AMERICAN PUBLIC EDUCATION INC COM 02913V103 26,607 716,005 SH   SOLE   716,005 0 0
AMERICAN TOWER CORP COM 03027X100 73,436 1,003,636 SH   SOLE   1,003,636 0 0
ANADARKO PETROLEUM CORP COM 032511107 627 7,300 SH   SOLE   7,300 0 0
ANSYS INC COM 03662Q105 171,951 2,352,269 SH   SOLE   2,352,269 0 0
APACHE CORP COM 037411105 243 2,899 SH   SOLE   2,899 0 0
APPLE COMPUTER INC COM 037833100 692 1,745 SH   SOLE   1,745 0 0
APPLIED MINERALS COM 03823m100 259 217,600 SH   SOLE   217,600 0 0
ATRION CORP COM 049904105 921 4,209 SH   SOLE   4,209 0 0
AUTOMATIC DATA PROCESSING COM 053015103 2,233 32,425 SH   SOLE   32,425 0 0
BECTON DICKINSON & CO COM 075887109 217 2,200 SH   SOLE   2,200 0 0
BERKSHIRE HATHAWAY INC COM 084670108 1,180 7 SH   SOLE   7 0 0
BERKSHIRE HATHAWAY INC. DEL CL COM 084670702 2,751 24,579 SH   SOLE   24,579 0 0
CANADIAN NATIONAL RAILROAD CO COM 136375102 973 10,000 SH   SOLE   10,000 0 0
CAPITAL ONE FINANCIAL COM 14040H105 1,759 28,009 SH   SOLE   28,009 0 0
CARMAX INC COM 143130102 1,258 27,250 SH   SOLE   27,250 0 0
CARTERS, INC. COM 146229109 25,263 341,064 SH   SOLE   341,064 0 0
CELGENE CORP COM 151020104 74,870 640,024 SH   SOLE   640,024 0 0
CHEVRON CORP COM 166764100 1,580 13,350 SH   SOLE   13,350 0 0
CISCO SYSTEMS INC COM 17275R102 2,643 108,614 SH   SOLE   108,614 0 0
CLEAN HARBORS INC COM 184496107 55,047 1,089,399 SH   SOLE   1,089,399 0 0
COCA COLA CO COM 191216100 1,089 27,162 SH   SOLE   27,162 0 0
COLGATE-PALMOLIVE COM 194162103 573 10,000 SH   SOLE   10,000 0 0
COMCAST CORP - A COM 20030N101 548 13,125 SH   SOLE   13,125 0 0
COMCAST CORP - A - SPL COM 20030N200 3,361 84,713 SH   SOLE   84,713 0 0
CONCHO RESOURCES INC COM 20605P101 79,617 950,997 SH   SOLE   950,997 0 0
CONCUR TECHNOLOGIES, INC. COM 206708109 96,519 1,186,032 SH   SOLE   1,186,032 0 0
CORE LABORATORIES NV COM N22717107 52,501 346,173 SH   SOLE   346,173 0 0
COSTAR GROUP INC. COM 22160n109 75,063 581,567 SH   SOLE   581,567 0 0
CROWN CASTLE INTL CORP COM 228227104 5,242 72,409 SH   SOLE   72,409 0 0
DEALERTRACK TECHNOLOGIES INC COM 242309102 67,555 1,906,715 SH   SOLE   1,906,715 0 0
DENTSPLY INTL COM 249030107 756 18,466 SH   SOLE   18,466 0 0
DONALDSON INC COM 257651109 4,846 135,907 SH   SOLE   135,907 0 0
DUKE REALTY CORP COM 264411505 242 15,550 SH   SOLE   15,550 0 0
EAST WEST BANCORP INC COM 27579R104 421 15,300 SH   SOLE   15,300 0 0
ECOLAB INC COM 278865100 93,225 1,094,315 SH   SOLE   1,094,315 0 0
ELI LILLY & CO COM 532457108 494 10,054 SH   SOLE   10,054 0 0
EMERSON COM 291011104 349 6,401 SH   SOLE   6,401 0 0
ENTERPRISE PRODUCTS PARTNERS L COM 293792107 544 8,750 SH   SOLE   8,750 0 0
EQT CORPORATION COM 26884L109 4,357 54,901 SH   SOLE   54,901 0 0
EQUITY RESIDENTIAL PROPERTYS I COM 29476l107 447 7,696 SH   SOLE   7,696 0 0
EUROSEAS LTD COM Y23592200 12 11,400 SH   SOLE   11,400 0 0
EXAMWORKS GROUP INC. COM 30066a105 12,728 599,551 SH   SOLE   599,551 0 0
EXONE COM 302104104 309 5,000 SH   SOLE   5,000 0 0
EXPEDITORS INTERNATIONAL COM 302130109 114,904 3,020,611 SH   SOLE   3,020,611 0 0
EXPONENT INC. COM 30214U102 31,135 526,726 SH   SOLE   526,726 0 0
EXPRESS SCRIPTS INC COM 30219G108 1,114 18,036 SH   SOLE   18,036 0 0
EXXON MOBIL CORP COM 30231G102 1,822 20,169 SH   SOLE   20,169 0 0
FASTENAL CO COM 311900104 240,936 5,261,769 SH   SOLE   5,261,769 0 0
FINANCIAL ENGINES INC COM 317485100 49,465 1,084,989 SH   SOLE   1,084,989 0 0
FISERV INC COM 337738108 3,191 36,501 SH   SOLE   36,501 0 0
FORTINET INC COM 34959e109 1,194 68,222 SH   SOLE   68,222 0 0
FREEPORT MCMORAN COPPER & GOLD COM 35671D857 423 15,314 SH   SOLE   15,314 0 0
GARDNER DENVER INC COM 365558105 420 5,590 SH   SOLE   5,590 0 0
GENERAL ELECTRIC COM 369604103 3,022 130,313 SH   SOLE   130,313 0 0
GENUINE PARTS COMPANY COM 372460105 273 3,499 SH   SOLE   3,499 0 0
GILEAD SCIENCES INC. COM 375558103 318 6,200 SH   SOLE   6,200 0 0
GOOGLE INC CL A COM 38259P508 396 450 SH   SOLE   450 0 0
HCP INC COM 40414L109 5,654 124,432 SH   SOLE   124,432 0 0
HEALTHCARE SERVICES GROUP INC COM 421906108 54,730 2,232,049 SH   SOLE   2,232,049 0 0
HESS CORPORATION COM 42809h107 359 5,402 SH   SOLE   5,402 0 0
HOME DEPOT COM 437076102 213 2,750 SH   SOLE   2,750 0 0
HOVNANIAN ENTERPRISES INC COM 442487203 252 45,000 SH   SOLE   45,000 0 0
IDEXX LABORATORIES, INC. COM 45168D104 423 4,718 SH   SOLE   4,718 0 0
ILLUMINA INC COM 452327109 24,396 325,982 SH   SOLE   325,982 0 0
INNERWORKINGS INC COM 45773Y105 28,539 2,630,352 SH   SOLE   2,630,352 0 0
INTEL CORP COM 458140100 16,256 670,918 SH   SOLE   670,918 0 0
INTERMAP TECHNOLOGIES CORP COM 458977204 35 75,000 SH   SOLE   75,000 0 0
INTL BUSINESS MACH CORP COM 459200101 2,946 15,413 SH   SOLE   15,413 0 0
J P MORGAN CHASE & CO COM 46625H100 613 11,604 SH   SOLE   11,604 0 0
JACOBS ENGINEERING CP INC COM 469814107 101,252 1,836,611 SH   SOLE   1,836,611 0 0
JAMBA, INC. COM 47023A101 224 15,000 SH   SOLE   15,000 0 0
JOHNSON & JOHNSON COM 478160104 8,958 104,329 SH   SOLE   104,329 0 0
JOHNSON CONTROLS INC COM 478366107 276 7,716 SH   SOLE   7,716 0 0
KINDER MORGAN MGT LLC COM 49455U100 791 9,458 SH   SOLE   9,458 0 0
LABORATORY CORP OF AMERICA HOL COM 50540R409 6,966 69,586 SH   SOLE   69,586 0 0
LANDAUER, INC. COM 51476k103 300 6,212 SH   SOLE   6,212 0 0
LINCOLN NATL CORP COM 534187109 246 6,736 SH   SOLE   6,736 0 0
LKQ CORP COM 501889208 125,336 4,867,405 SH   SOLE   4,867,405 0 0
LYNAS CORP LTD COM Q5683J103 49 135,000 SH   SOLE   135,000 0 0
M&T BANK CORP COM 55261F104 351 3,138 SH   SOLE   3,138 0 0
MACY'S, INC. COM 55616P104 281 5,863 SH   SOLE   5,863 0 0
MAG SILVER CORP COM 55903Q104 88 15,000 SH   SOLE   15,000 0 0
MAGELLAN MIDSTREAM PARTNERS LP COM 559080106 327 6,000 SH   SOLE   6,000 0 0
MARKEL CORP COM 570535104 109,496 207,792 SH   SOLE   207,792 0 0
MARKET VECTORS JUNIOR GOLD MIN COM 57061r544 150 16,350 SH   SOLE   16,350 0 0
MASTERCARD INC CL A COM 57636Q104 1,445 2,515 SH   SOLE   2,515 0 0
McCORMICK & CO COM 579780206 993 14,110 SH   SOLE   14,110 0 0
MERCK & CO COM 58933Y105 1,142 24,587 SH   SOLE   24,587 0 0
MERIDIAN BIOSCIENCE INC. COM 589584101 297 13,800 SH   SOLE   13,800 0 0
MHI HOSPITALITY CORP COM 55302L102 53 12,125 SH   SOLE   12,125 0 0
MICROSOFT CORP COM 594918104 2,967 85,876 SH   SOLE   85,876 0 0
MIDDLEBY CORP COM 596278101 1,686 9,914 SH   SOLE   9,914 0 0
MONRO MUFFLER BRAKE COM 610236101 466 9,691 SH   SOLE   9,691 0 0
MONSANTO CO COM 61166W101 13,325 134,868 SH   SOLE   134,868 0 0
MOSIAC COMPANY COM 61945C103 9,114 169,367 SH   SOLE   169,367 0 0
NANOSPHERE INC COM 63009f105 138 45,000 SH   SOLE   45,000 0 0
NATIONAL AMERICAN UNIV HOLDING COM 63245Q105 6,413 1,714,780 SH   SOLE   1,714,780 0 0
NATIONAL INFORMATION CONSORTIU COM 62914b100 21,298 1,288,448 SH   SOLE   1,288,448 0 0
NEOGEN CORP COM 640491106 400 7,200 SH   SOLE   7,200 0 0
NESTLE S.A. COM 641069406 280 4,274 SH   SOLE   4,274 0 0
NYMOX PHARMACEUTICAL CORP COM 67076p102 76 15,000 SH   SOLE   15,000 0 0
O REILLY AUTOMOTIVE INC COM 67103H107 13,861 123,079 SH   SOLE   123,079 0 0
ODYSSEY MARINE EXPLORATION COM 676118102 133 45,000 SH   SOLE   45,000 0 0
ONEBEACON INSURANCE GP COM G67742109 305 21,040 SH   SOLE   21,040 0 0
PAYCHEX COM 704326107 5,954 163,088 SH   SOLE   163,088 0 0
PEPSICO INC COM 713448108 355 4,345 SH   SOLE   4,345 0 0
PFIZER INC COM 717081103 1,147 40,934 SH   SOLE   40,934 0 0
PHILIP MORRIS INTL COM 718172109 457 5,275 SH   SOLE   5,275 0 0
PINNACLE WEST CAPITOL CORP COM 723484101 244 4,400 SH   SOLE   4,400 0 0
PNC FINANCIAL SVCS INC COM 693475105 1,902 26,087 SH   SOLE   26,087 0 0
POLYPORE INTERNATIONAL INC. COM 73179V103 10,922 271,023 SH   SOLE   271,023 0 0
POTASH CORP OF SASKATCHEWAN COM 73755L107 64,127 1,681,812 SH   SOLE   1,681,812 0 0
PRECISION CASTPARTS CORP COM 740189105 407 1,800 SH   SOLE   1,800 0 0
PRICE SMART INC COM 741511109 23,941 273,209 SH   SOLE   273,209 0 0
PROCTER & GAMBLE CO COM 742718109 24,105 313,093 SH   SOLE   313,093 0 0
QUALCOMM INC COM 747525103 123,318 2,018,630 SH   SOLE   2,018,630 0 0
QUANTA SERVICES INC COM 74762e102 2,676 101,142 SH   SOLE   101,142 0 0
RANGE RESOURCES CORP COM 75281A109 62,311 805,890 SH   SOLE   805,890 0 0
REALPAGE, INC. COM 75606n109 10,940 596,502 SH   SOLE   596,502 0 0
RED HAT INC. COM 756577102 39,091 817,454 SH   SOLE   817,454 0 0
RENAISSANCE RE HOLDINGS LTD COM G7496G103 860 9,910 SH   SOLE   9,910 0 0
RESMED INC COM 761152107 90,630 2,008,197 SH   SOLE   2,008,197 0 0
ROPER INDUSTRIES, INC COM 776696106 94,188 758,237 SH   SOLE   758,237 0 0
SBA COMMUNICATIONS CORP COM 78388J106 1,750 23,609 SH   SOLE   23,609 0 0
SCHLUMBERGER LTD COM 806857108 99,779 1,392,393 SH   SOLE   1,392,393 0 0
SEI INVESTMENTS CO COM 784117103 103,599 3,643,996 SH   SOLE   3,643,996 0 0
SILVER WHEATON CORP COM 828336107 384 19,500 SH   SOLE   19,500 0 0
SOUTHWESTERN ENERGY CO COM 845467109 42,642 1,167,325 SH   SOLE   1,167,325 0 0
STERICYCLE INC COM 858912108 115,976 1,050,226 SH   SOLE   1,050,226 0 0
STONEMOR PARTNERS LP COM 86183Q100 302 12,000 SH   SOLE   12,000 0 0
STRYKER CORP COM 863667101 298 4,609 SH   SOLE   4,609 0 0
T ROWE PRICE GROUP INC COM 74144T108 98,525 1,345,969 SH   SOLE   1,345,969 0 0
TECHNE CORP COM 878377100 976 14,134 SH   SOLE   14,134 0 0
TELEFLEX INC COM 879369106 213 2,750 SH   SOLE   2,750 0 0
TRIMBLE NAVIGATION LTD COM 896239100 117,789 4,532,085 SH   SOLE   4,532,085 0 0
TYLER TECHNOLOGIES INC COM 902252105 41,964 612,171 SH   SOLE   612,171 0 0
U.S. BANCORP COM 902973304 1,141 31,567 SH   SOLE   31,567 0 0
UNDER ARMOUR, INC COM 904311107 239 4,000 SH   SOLE   4,000 0 0
UNITED TECHNOLOGIES CORP COM 913017109 351 3,776 SH   SOLE   3,776 0 0
VENTAS INC COM 92276f100 3,294 47,416 SH   SOLE   47,416 0 0
VERIZON COMMUNICATIONS COM 92343V104 266 5,285 SH   SOLE   5,285 0 0
VISA INC COM 92826C839 99,765 545,909 SH   SOLE   545,909 0 0
WAGEWORKS INC COM 930427109 58,798 1,706,764 SH   SOLE   1,706,764 0 0
WALT DISNEY CO COM 254687106 563 8,919 SH   SOLE   8,919 0 0
WASTE CONNECTIONS INC COM 941053100 85,485 2,077,899 SH   SOLE   2,077,899 0 0
WELLS FARGO & CO COM 949746101 275 6,655 SH   SOLE   6,655 0 0
WHOLE FOODS MARKET COM 966837106 813 15,800 SH   SOLE   15,800 0 0
WR BERKLEY CORP COM 084423102 3,578 87,578 SH   SOLE   87,578 0 0
VANGUARD DIVIDEND ETFS 921908844 488 7,375 SH   SOLE   7,375 0 0
VANGUARD FTSE ALL-WORLD EX-US ETFS 922042775 2,389 54,022 SH   SOLE   54,022 0 0
VANGUARD FTSE EMERGING MARKETS ETFS 922042858 501 12,925 SH   SOLE   12,925 0 0
VANGUARD HIGH DIVIDEND YIELD E ETFS 921946406 245 4,350 SH   SOLE   4,350 0 0
VANGUARD INDEX REIT ETF ETFS 922908553 383 5,580 SH   SOLE   5,580 0 0