28 our clinicians are also responsible for managing and operating our patient-care centers and are compensated , in part , based on their success in managing costs and collecting accounts receivable . we provide centralized administrative , marketing and materials management services to take advantage of economies of scale and to increase the time clinicians have to provide patient-care . in areas where we have multiple patient-care centers , we also utilize shared fabrication facilities where technicians fabricate devices for clinicians in that region . distribution services we distribute o & p components to our customers and to our own patient-care centers through our wholly-owned subsidiary , sps , which is the nation 's largest o & p distributor . we are also a leading manufacturer and distributor of therapeutic footwear for diabetic patients in the podiatric market . for the year ended december 31 , 2011 , 34.6 % or approximately $ 100.5 million of sps distribution sales were to third-party o & p services providers , and the balance of approximately $ 190.3 million represented intercompany sales to our patient-care centers . sps maintains in inventory approximately 29,000 individual skus manufactured by more than 300 different companies . sps maintains distribution facilities in california , florida , georgia , illinois , pennsylvania , and texas , which allows us to deliver products via ground shipment anywhere in the contiguous united states typically within two business days . our distribution business enables us to : centralize our purchasing and thus lower our material costs by negotiating purchasing discounts from manufacturers ; reduce our patient-care center inventory levels and improve inventory turns ; perform inventory quality control ; encourage our patient-care centers to use clinically appropriate products that enhance our profit margins ; and coordinate new product development efforts with key vendor `` partners `` . marketing of our distribution services is conducted on a national basis through a dedicated sales force , print and e-commerce catalogues , and exhibits at industry and medical meetings and conventions . we direct specialized catalogues to segments of the healthcare industry , such as orthopedic surgeons , physical and occupational therapists , and podiatrists . therapeutic solutions we provide therapeutic solutions to the o & p market and post-acute rehabilitation market through our subsidiaries in , inc. and acp . on december 1 , 2010 we acquired acp , which is the nation 's leading provider of rehabilitation technologies and integrated clinical programs to rehabilitation providers . acp 's unique value proposition is to provide its customers with a full-service `` total solutions `` approach encompassing proven medical technology , evidence based clinical programs , and continuous onsite therapist education and training . acp 's services support increasingly advanced treatment options for a broader patient population and more medically complex conditions . acp has contracts to serve more than 4,000 skilled nursing facilities nationwide , including 21 of the 25 largest national providers . acp 's contracts contain negotiated pricing and service levels with terms ranging from one to five years . acp generally bills its customers monthly and revenue is recognized based upon the contractual terms of the agreements . in , inc. specializes in product development and commercialization of emerging products . working with the inventors under licensing and consulting agreements , in , inc. commercializes the design , obtains regulatory approvals , develops clinical protocols for the technology , and then introduces the 29 devices to the marketplace through a variety of distribution channels . in , inc. has two products ; the walkaide system which benefits patients with a condition referred to as drop foot and the v-hold which is active suction technology used in lower extremity prosthetic devices . the walkaide system is currently reimbursable from medicare beneficiaries with foot drop due to incomplete spinal cord injuries . in , inc. is currently conducting clinical trials in an effort to gain additional coverage for stroke patients with foot drop which represents the largest potential patient population . in , inc. anticipates that these trials will be fully enrolled by the end of the second quarter of 2011 with submission of data to cms in the fourth quarter of 2011 or early 2012. in addition to reimbursement from medicare and medicaid , in , inc. has been working with commercial insurance companies and has had limited success in receiving coverage for the walkaide . the walkaide and v-hold are sold in the united states through our patient-care centers and sps . in , inc. is also marketing the walkaide internationally through licensed distributors . results and outlook net sales for the year ended december 31 , 2011 increased by $ 101.2 million , or 12.4 % , to $ 918.5 million from $ 817.4 million for the year ended december 31 , 2010. the sales increase was principally the result of an $ 18.4 million , or 2.6 % , increase in same-center sales in our patient-care services segment , a $ 4.9 million , or 5.1 % , increase in sales of our distribution segment , $ 57.4 million in increased sales from our therapeutic solutions segment , resulting primarily from the december 2010 acquisition of acp , and a $ 20.5 million increase principally related to sales from acquired patient-care entities . income from operations and net income were $ 116.8 million and $ 55.0 million , respectively , in 2011 compared to $ 81.4 million and $ 21.4 million , respectively , in the prior year . our cash flow from operations increased $ 7.6 million to $ 61.8 million in 2011 , from $ 54.2 million in 2010 primarily due to normal changes in working capital . as of december 31 , 2011 , $ 297.0 million , or 58.5 % , of our total debt of $ 508.0 million was subject to variable interest rates . story_separator_special_tag although we believe the measurement of our liabilities for uncertain tax positions is reasonable , no assurance can be given that the final outcome of these matters will not be different than what is reflected in the historical income tax provisions and accruals . if additional taxes are assessed as a result of an audit or litigation , it could have a material effect on the income tax provision and net income in the period or periods for which that determination is made . we operate within multiple taxing jurisdictions and are subject to audit in these jurisdictions . these audits can involve complex issues which may require an extended period of time to resolve and could result in additional assessments of income tax . we believe adequate provisions for income taxes have been made for all periods . supplemental executive retirement plan : benefit costs and liabilities balances are calculated based on certain assumptions including benefits earned , discount rates , interest costs , mortality rates and other factors . actual results that differ from the assumptions are accumulated and amortized over future periods , affecting the recorded obligation and expense in future periods . the following assumptions were used in the calculation of the net benefit cost and obligation at december 31 : replace_table_token_11_th we believe the assumptions used are appropriate . however , changes in assumptions or differences in actual experience may affect our benefit obligation and future expenses . new accounting guidance in may 2011 , the fasb issued accounting standards update ( `` asu `` ) 2011-04 , `` amendments to achieve common fair value measurement and disclosure requirements in u.s. gaap and ifrss , `` which amends asc 820 , `` fair value measurement . `` the amended guidance changes the wording used to describe many requirements in u.s. gaap for measuring fair value and for disclosing information about fair value measurements . additionally , the amendments clarify the fasb 's intent about the application of existing fair value measurement requirements . the guidance provided in asu no . 2011-04 is effective for interim and annual periods beginning after december 15 , 2011 and is applied prospectively . the provisions are effective for the company 's year ended december 31 , 2012. the company does not expect the adoption of these provisions to have a material effect on the consolidated financial statements . 35 in june 2011 , the fasb issued accounting standards update ( `` asu `` ) 2011-05 , `` comprehensive income ( topic 220 ) , `` which changes the presentation of comprehensive income . the amended guidance gives companies the option to present the total of comprehensive income , the components of net income , and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements . in december 2011 , the fasb issued an amendment to asu 2011-05 which deferred the effective date for amendments to the presentation of reclassifications of items out of accumulated other comprehensive income . the deferral date is undetermined at this time . all other requirements of asu 2011-05 are not affected by this update . the guidance provided in asu no . 2011-05 is effective for interim and annual periods beginning after december 15 , 2011 and is applied retrospectively . the provisions are effective for the company 's year ended december 31 , 2012. the company does not expect the adoption of these provisions to have a material effect on the consolidated financial statements . in july 2011 , the fasb issued `` presentation and disclosures of patient service revenue , provision for bad debts and the allowance for doubtful accounts for certain health care entities . `` the objective of this update is to provide financial statement users with greater transparency about a health care entity 's net patient service revenue and the related allowance for doubtful accounts . this update provides information to assist financial statement users in assessing an entity 's sources of net patient service revenue and related changes in its allowance for doubtful accounts . the amendments require health care entities that recognize significant amounts of patient service revenue at the time the services are rendered even though they do not assess the patient 's ability to pay to present the provision for bad debts related to patient service revenue as a deduction from patient service revenue ( net of contractual allowances and discounts ) on their statement of operations . the amendments in this update require certain health care entities to change the presentation of their statement of operations by reclassifying the provision for bad debts associated with patient service revenue from an operating expense to a deduction from patient service revenue ( net of contractual allowances and discounts ) . additionally , those health care entities are required to provide enhanced disclosure about their policies for recognizing revenue and assessing bad debts . the amendments also require disclosures of patient service revenue ( net of contractual allowances and discounts ) as well as qualitative and quantitative information about changes in the allowance for doubtful accounts . the guidance provided in asu no . 2011-07 is effective for interim and annual periods beginning after december 15 , 2011 and is applied prospectively , except for the provision for bad debts related to patient service revenue as a deduction from patient service revenue ( net of contractual allowances and discounts ) on the statement of operations . the provisions are effective for the company 's year ended december 31 , 2012. the company is currently evaluating the requirements of this update and has not yet determined the impact on its consolidated financial statements . 36 results of operations the following table sets forth , for the periods indicated , certain items from our statements of operations as a percentage of our net sales : replace_table_token_12_th year-ended december 31 , 2011 compared with the year ended

cash flows our working capital at december 31 , 2011 was $ 241.7 million , compared to $ 185.8 million at december 31 , 2010. the increase in working capital is primarily due to the increase in inventory , accounts receivable and reduced levels of incentive compensation payable . days sales outstanding ( `` dso '' ) , which is the number of days between the billing for our o & p services and the date of our receipt of payment thereof , for the year ended december 31 , 2011 increased to 54 days compared to 52 days for the same period last year . the increase in dso is primarily due to an increase in accounts receivable at the cares pilot program within our patient-care services segment which is experiencing delays in its billing and collections processes . net cash provided by operating activities was $ 61.8 million for the year ended december 31 , 2011 , compared to $ 54.2 million in the prior year . the increase in current year operating cash flows resulted primarily from increased net sales in 2011 , and the absence of cash paid related to the acquisition costs of acp in 2010 , and the expenses related to relocation of corporate headquarters in 2010. net cash used in investing activities was $ 46.9 million for the year ended december 31 , 2011 compared to $ 186.0 million in the prior year . in 2011 , 2010 , and 2009 , we invested $ 28.1 million , $ 30.6 million , and $ 21.3 million , respectively , in improvements to our patient-care centers , upgrades to our computer hardware and software , and purchases of equipment leased to third parties by our therapeutic solutions segment . in 2011 , we acquired eight o & p companies operating a total of 21 patient-care centers at an aggregate purchase price of $ 24.9 million . in 2010 , we acquired five o & p companies operating a total of six patient-care centers at an aggregate purchase price of $ 10.6 million , and we completed the acquisition of acp for a purchase price of approximately $ 157.8 million .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```cash flows our working capital at december 31 , 2011 was $ 241.7 million , compared to $ 185.8 million at december 31 , 2010. the increase in working capital is primarily due to the increase in inventory , accounts receivable and reduced levels of incentive compensation payable . days sales outstanding ( `` dso '' ) , which is the number of days between the billing for our o & p services and the date of our receipt of payment thereof , for the year ended december 31 , 2011 increased to 54 days compared to 52 days for the same period last year . the increase in dso is primarily due to an increase in accounts receivable at the cares pilot program within our patient-care services segment which is experiencing delays in its billing and collections processes . net cash provided by operating activities was $ 61.8 million for the year ended december 31 , 2011 , compared to $ 54.2 million in the prior year . the increase in current year operating cash flows resulted primarily from increased net sales in 2011 , and the absence of cash paid related to the acquisition costs of acp in 2010 , and the expenses related to relocation of corporate headquarters in 2010. net cash used in investing activities was $ 46.9 million for the year ended december 31 , 2011 compared to $ 186.0 million in the prior year . in 2011 , 2010 , and 2009 , we invested $ 28.1 million , $ 30.6 million , and $ 21.3 million , respectively , in improvements to our patient-care centers , upgrades to our computer hardware and software , and purchases of equipment leased to third parties by our therapeutic solutions segment . in 2011 , we acquired eight o & p companies operating a total of 21 patient-care centers at an aggregate purchase price of $ 24.9 million . in 2010 , we acquired five o & p companies operating a total of six patient-care centers at an aggregate purchase price of $ 10.6 million , and we completed the acquisition of acp for a purchase price of approximately $ 157.8 million .
```    
 Suspicious Activity Report : 28 our clinicians are also responsible for managing and operating our patient-care centers and are compensated , in part , based on their success in managing costs and collecting accounts receivable . we provide centralized administrative , marketing and materials management services to take advantage of economies of scale and to increase the time clinicians have to provide patient-care . in areas where we have multiple patient-care centers , we also utilize shared fabrication facilities where technicians fabricate devices for clinicians in that region . distribution services we distribute o & p components to our customers and to our own patient-care centers through our wholly-owned subsidiary , sps , which is the nation 's largest o & p distributor . we are also a leading manufacturer and distributor of therapeutic footwear for diabetic patients in the podiatric market . for the year ended december 31 , 2011 , 34.6 % or approximately $ 100.5 million of sps distribution sales were to third-party o & p services providers , and the balance of approximately $ 190.3 million represented intercompany sales to our patient-care centers . sps maintains in inventory approximately 29,000 individual skus manufactured by more than 300 different companies . sps maintains distribution facilities in california , florida , georgia , illinois , pennsylvania , and texas , which allows us to deliver products via ground shipment anywhere in the contiguous united states typically within two business days . our distribution business enables us to : centralize our purchasing and thus lower our material costs by negotiating purchasing discounts from manufacturers ; reduce our patient-care center inventory levels and improve inventory turns ; perform inventory quality control ; encourage our patient-care centers to use clinically appropriate products that enhance our profit margins ; and coordinate new product development efforts with key vendor `` partners `` . marketing of our distribution services is conducted on a national basis through a dedicated sales force , print and e-commerce catalogues , and exhibits at industry and medical meetings and conventions . we direct specialized catalogues to segments of the healthcare industry , such as orthopedic surgeons , physical and occupational therapists , and podiatrists . therapeutic solutions we provide therapeutic solutions to the o & p market and post-acute rehabilitation market through our subsidiaries in , inc. and acp . on december 1 , 2010 we acquired acp , which is the nation 's leading provider of rehabilitation technologies and integrated clinical programs to rehabilitation providers . acp 's unique value proposition is to provide its customers with a full-service `` total solutions `` approach encompassing proven medical technology , evidence based clinical programs , and continuous onsite therapist education and training . acp 's services support increasingly advanced treatment options for a broader patient population and more medically complex conditions . acp has contracts to serve more than 4,000 skilled nursing facilities nationwide , including 21 of the 25 largest national providers . acp 's contracts contain negotiated pricing and service levels with terms ranging from one to five years . acp generally bills its customers monthly and revenue is recognized based upon the contractual terms of the agreements . in , inc. specializes in product development and commercialization of emerging products . working with the inventors under licensing and consulting agreements , in , inc. commercializes the design , obtains regulatory approvals , develops clinical protocols for the technology , and then introduces the 29 devices to the marketplace through a variety of distribution channels . in , inc. has two products ; the walkaide system which benefits patients with a condition referred to as drop foot and the v-hold which is active suction technology used in lower extremity prosthetic devices . the walkaide system is currently reimbursable from medicare beneficiaries with foot drop due to incomplete spinal cord injuries . in , inc. is currently conducting clinical trials in an effort to gain additional coverage for stroke patients with foot drop which represents the largest potential patient population . in , inc. anticipates that these trials will be fully enrolled by the end of the second quarter of 2011 with submission of data to cms in the fourth quarter of 2011 or early 2012. in addition to reimbursement from medicare and medicaid , in , inc. has been working with commercial insurance companies and has had limited success in receiving coverage for the walkaide . the walkaide and v-hold are sold in the united states through our patient-care centers and sps . in , inc. is also marketing the walkaide internationally through licensed distributors . results and outlook net sales for the year ended december 31 , 2011 increased by $ 101.2 million , or 12.4 % , to $ 918.5 million from $ 817.4 million for the year ended december 31 , 2010. the sales increase was principally the result of an $ 18.4 million , or 2.6 % , increase in same-center sales in our patient-care services segment , a $ 4.9 million , or 5.1 % , increase in sales of our distribution segment , $ 57.4 million in increased sales from our therapeutic solutions segment , resulting primarily from the december 2010 acquisition of acp , and a $ 20.5 million increase principally related to sales from acquired patient-care entities . income from operations and net income were $ 116.8 million and $ 55.0 million , respectively , in 2011 compared to $ 81.4 million and $ 21.4 million , respectively , in the prior year . our cash flow from operations increased $ 7.6 million to $ 61.8 million in 2011 , from $ 54.2 million in 2010 primarily due to normal changes in working capital . as of december 31 , 2011 , $ 297.0 million , or 58.5 % , of our total debt of $ 508.0 million was subject to variable interest rates . story_separator_special_tag although we believe the measurement of our liabilities for uncertain tax positions is reasonable , no assurance can be given that the final outcome of these matters will not be different than what is reflected in the historical income tax provisions and accruals . if additional taxes are assessed as a result of an audit or litigation , it could have a material effect on the income tax provision and net income in the period or periods for which that determination is made . we operate within multiple taxing jurisdictions and are subject to audit in these jurisdictions . these audits can involve complex issues which may require an extended period of time to resolve and could result in additional assessments of income tax . we believe adequate provisions for income taxes have been made for all periods . supplemental executive retirement plan : benefit costs and liabilities balances are calculated based on certain assumptions including benefits earned , discount rates , interest costs , mortality rates and other factors . actual results that differ from the assumptions are accumulated and amortized over future periods , affecting the recorded obligation and expense in future periods . the following assumptions were used in the calculation of the net benefit cost and obligation at december 31 : replace_table_token_11_th we believe the assumptions used are appropriate . however , changes in assumptions or differences in actual experience may affect our benefit obligation and future expenses . new accounting guidance in may 2011 , the fasb issued accounting standards update ( `` asu `` ) 2011-04 , `` amendments to achieve common fair value measurement and disclosure requirements in u.s. gaap and ifrss , `` which amends asc 820 , `` fair value measurement . `` the amended guidance changes the wording used to describe many requirements in u.s. gaap for measuring fair value and for disclosing information about fair value measurements . additionally , the amendments clarify the fasb 's intent about the application of existing fair value measurement requirements . the guidance provided in asu no . 2011-04 is effective for interim and annual periods beginning after december 15 , 2011 and is applied prospectively . the provisions are effective for the company 's year ended december 31 , 2012. the company does not expect the adoption of these provisions to have a material effect on the consolidated financial statements . 35 in june 2011 , the fasb issued accounting standards update ( `` asu `` ) 2011-05 , `` comprehensive income ( topic 220 ) , `` which changes the presentation of comprehensive income . the amended guidance gives companies the option to present the total of comprehensive income , the components of net income , and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements . in december 2011 , the fasb issued an amendment to asu 2011-05 which deferred the effective date for amendments to the presentation of reclassifications of items out of accumulated other comprehensive income . the deferral date is undetermined at this time . all other requirements of asu 2011-05 are not affected by this update . the guidance provided in asu no . 2011-05 is effective for interim and annual periods beginning after december 15 , 2011 and is applied retrospectively . the provisions are effective for the company 's year ended december 31 , 2012. the company does not expect the adoption of these provisions to have a material effect on the consolidated financial statements . in july 2011 , the fasb issued `` presentation and disclosures of patient service revenue , provision for bad debts and the allowance for doubtful accounts for certain health care entities . `` the objective of this update is to provide financial statement users with greater transparency about a health care entity 's net patient service revenue and the related allowance for doubtful accounts . this update provides information to assist financial statement users in assessing an entity 's sources of net patient service revenue and related changes in its allowance for doubtful accounts . the amendments require health care entities that recognize significant amounts of patient service revenue at the time the services are rendered even though they do not assess the patient 's ability to pay to present the provision for bad debts related to patient service revenue as a deduction from patient service revenue ( net of contractual allowances and discounts ) on their statement of operations . the amendments in this update require certain health care entities to change the presentation of their statement of operations by reclassifying the provision for bad debts associated with patient service revenue from an operating expense to a deduction from patient service revenue ( net of contractual allowances and discounts ) . additionally , those health care entities are required to provide enhanced disclosure about their policies for recognizing revenue and assessing bad debts . the amendments also require disclosures of patient service revenue ( net of contractual allowances and discounts ) as well as qualitative and quantitative information about changes in the allowance for doubtful accounts . the guidance provided in asu no . 2011-07 is effective for interim and annual periods beginning after december 15 , 2011 and is applied prospectively , except for the provision for bad debts related to patient service revenue as a deduction from patient service revenue ( net of contractual allowances and discounts ) on the statement of operations . the provisions are effective for the company 's year ended december 31 , 2012. the company is currently evaluating the requirements of this update and has not yet determined the impact on its consolidated financial statements . 36 results of operations the following table sets forth , for the periods indicated , certain items from our statements of operations as a percentage of our net sales : replace_table_token_12_th year-ended december 31 , 2011 compared with the year ended

