sc13g

CRANSHIRE CAPITAL, L.P.

Downsview Capital, Inc., its general partner

/s/ Mitchell P. Kopin

Mitchell P. Kopin, President

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. )*

ARCA biopharma, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

00211Y100

(CUSIP Number)

April 18, 2011

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

a.   o Rule 13d-1(b)
b.   þ Rule 13d-1(c)
c.   o Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).


CUSIP No.		00211Y100


1	NAMES OF REPORTING PERSONS I.R.S. Identification Nos. of above persons (entities only) Cranshire Capital, L.P.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) o

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Illinois

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			676,444

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			676,444

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	676,444 (see Item 4)

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	6.4% (see Item 4)

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	PN

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CUSIP No.		00211Y100


1	NAMES OF REPORTING PERSONS I.R.S. Identification Nos. of above persons (entities only) Downsview Capital, Inc.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) o

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	Illinois

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			753,078

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			753,078

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	753,078 (see Item 4)

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	7.2% (see Item 4)

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO; HC

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CUSIP No.		00211Y100


1	NAMES OF REPORTING PERSONS I.R.S. Identification Nos. of above persons (entities only) Mitchell P. Kopin


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) o

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States of America

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			753,078

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			753,078

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	753,078 (see Item 4)

10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)

	o

11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

	7.2% (see Item 4)

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	IN; HC

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Item 1.

(a) Name of Issuer

ARCA biopharma, Inc. (the “Issuer”)

(b) Address of Issuer’s Principal Executive Offices

8001 Arista Place, Suite 200
Broomfield, Colorado 80021

Item 2.

(a) Name of Person Filing
(b) Address of Principal Business Office or, if none, Residence
(c) Citizenship

This Schedule 13G is being filed on behalf of (i) Cranshire Capital, L.P., an Illinois limited partnership (“Cranshire”), (ii) Downsview Capital, Inc., an Illinois corporation (“Downsview”), and (iii) Mitchell P. Kopin, an individual who is a citizen of the United States of America (“Mr. Kopin,” together with Cranshire and Downsview, the “Reporting Persons”).

Downsview also serves as the investment manager to a managed account (the “Managed Account”). In such capacity, Downsview exercises voting and investment power over the shares of Common Stock held for the account of the Managed Account.

The Reporting Persons have entered into a Joint Filing Agreement, a copy of which is filed with this Schedule 13G as Exhibit 1, pursuant to which the Reporting Persons have agreed to file this Schedule 13G jointly in accordance with the provisions of Rule 13d-1(k) of the Securities Exchange Act of 1934, as amended.

The principal business office of all of the Reporting Persons is 3100 Dundee Road, Suite 703, Northbrook, Illinois 60062.

(d) Title of Class of Securities

Common stock, par value $0.001 per share, of the Issuer (the “Common Stock”).

(e) CUSIP Number

00211Y100

Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable.

Item 4. Ownership.

(a) and (b):

(i) As of the close of business on April 27, 2011, each of Downsview and Mr. Kopin may be deemed to have beneficial ownership of 753,078 shares of Common Stock, and all such shares of Common Stock represent beneficial ownership of approximately 7.2% of the Common Stock, based on (1) 8,834,535 shares of Common Stock issued and outstanding on April 15, 2011 as disclosed in the Form 424B5 Prospectus Supplement filed by the Issuer on April 18, 2011, plus (2) 1,680,672 shares of Common Stock in the aggregate issued on April 21, 2011 at the closing of the transaction described in the Form 8-K filed by the Issuer on April 18, 2011. The foregoing excludes (I) 529,411 shares of Common Stock issuable upon exercise of a warrant issued to Cranshire at the closing of the transaction described above (the “Warrant”) because the Warrant is not exercisable until the six (6) month anniversary of the date of issuance (and the Warrant also contains a blocker provision under which the holder thereof does not have the right to exercise the Warrant to the extent (but only to the extent) that such exercise would result in beneficial

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ownership by the holder thereof or any of its affiliates, of more than 4.9% of the Common Stock), and (II) 58,824 shares of Common Stock issuable upon exercise of a warrant issued to the Managed Account at the closing of the transaction described above (the “Managed Account Warrant”) because the Managed Account Warrant is not exercisable until the six (6) month anniversary of the date of issuance (and the Managed Account Warrant also contains a blocker provision under which the holder thereof does not have the right to exercise the Managed Account Warrant to the extent (but only to the extent) that such exercise would result in beneficial ownership by the holder thereof or any of its affiliates, of more than 4.9% of the Common Stock). Without such blocker provisions (and assuming the Warrant and Managed Account Warrant are currently exercisable), each of Downsview and Mr. Kopin may be deemed to have beneficial ownership of 1,341,313 shares of Common Stock.

(ii) As of the close of business on April 27, 2011, Cranshire may be deemed to have beneficial ownership of 676,444 shares of Common Stock, and all such shares of Common Stock represent beneficial ownership of approximately 6.4% of the Common Stock, based on (1) 8,834,535 shares of Common Stock issued and outstanding on April 15, 2011 as disclosed in the Form 424B5 Prospectus Supplement filed by the Issuer on April 18, 2011, plus (2) 1,680,672 shares of Common Stock in the aggregate issued on April 21, 2011 at the closing of the transaction described in the Form 8-K filed by the Issuer on April 18, 2011. The foregoing excludes 529,411 shares of Common Stock issuable upon exercise of the Warrant because the Warrant is not exercisable until the six (6) month anniversary of the date of issuance (and the Warrant also contains a blocker provision under which the holder thereof does not have the right to exercise the Warrant to the extent (but only to the extent) that such exercise would result in beneficial ownership by the holder thereof or any of its affiliates, of more than 4.9% of the Common Stock). Without such blocker provision (and assuming the Warrant is currently exercisable), Cranshire may be deemed to have beneficial ownership of 1,205,855 shares of Common Stock.

(i) Sole power to vote or to direct the vote: 0.

(ii) Shared power to vote or to direct the vote 753,078.

(iii) Sole power to dispose or to direct the disposition of 0.

(iv) Shared power to dispose or to direct the disposition of 753,078.

(ii) Number of shares as to which Cranshire has:

(i) Sole power to vote or to direct the vote: 0.

(ii) Shared power to vote or to direct the vote 676,444.

(iii) Sole power to dispose or to direct the disposition of 0.

(iv) Shared power to dispose or to direct the disposition of 676,444.

Item 5. Ownership of Five Percent or Less of a Class

Not applicable.

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Not applicable.

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company

Not applicable.

Item 8. Identification and Classification of Members of the Group

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Not applicable.

Item 9. Notice of Dissolution of Group

Not applicable.

Item 10. Certification

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: April 27, 2011


		DOWNSVIEW CAPITAL, INC.

		By: /s/ Mitchell P. Kopin Mitchell P. Kopin, President

		/s/ Mitchell P. Kopin Mitchell P. Kopin

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Exhibit 1

JOINT FILING AGREEMENT

The undersigned acknowledge and agree that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G may be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

Dated: April 27, 2011


		CRANSHIRE CAPITAL, L.P.

		By:		Downsview Capital, Inc., its general partner

		By:		/s/ Mitchell P. Kopin Mitchell P. Kopin, President

		DOWNSVIEW CAPITAL, INC.

		By:		/s/ Mitchell P. Kopin
		Mitchell P. Kopin, President

		/s/ Mitchell P. Kopin
		Mitchell P. Kopin

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