our revenue growth is dependent on our ability to develop and introduce new products to meet the changing technology and performance requirements of our customers , the diversification and expansion of our revenue base , and our ability to market our products in a manner that increases awareness for microinverter technology and differentiates us in the marketplace . 30 cost of revenues and gross profit cost of revenues is comprised primarily of product costs , warranty , manufacturing personnel and logistics costs , freight costs , depreciation and amortization of test equipment and hosting services costs . our product costs are impacted by technological innovations , such as advances in semiconductor integration and new product introductions , economies of scale resulting in lower component costs , and improvements in production processes and automation . certain costs , primarily personnel and depreciation and amortization of test equipment , are not directly affected by sales volume . we outsource our manufacturing to third-party contract manufacturers and generally negotiate product pricing with them on a quarterly basis . we believe our contract manufacturing partners have sufficient production capacity to meet the growing demand for our products for the foreseeable future . however , shortages in the supply of certain key raw materials could adversely affect our ability to meet customer demand for our products . in addition , third parties , including one of our contract manufacturers , serve as our logistics providers by warehousing and delivering our products in north america , europe , australia and new zealand . gross profit may vary from quarter to quarter and is primarily affected by our average selling prices , product cost , product mix , warranty costs ( including changes in estimates ) and sales volume fluctuations resulting from seasonality . operating expenses operating expenses consist of research and development , sales and marketing and general and administrative expenses . personnel-related costs are the most significant component of each of these expense categories and include salaries , benefits , payroll taxes , recruiting costs , sales commissions , incentive compensation and stock-based compensation . we expect personnel costs to continue to increase as we hire new employees to support our anticipated growth . we expect that each of the categories of operating expenses discussed below will increase in absolute dollars , but will decline as a percentage of total revenues in the long term . research and development expense includes personnel-related expenses such as salaries , incentive compensation , stock-based compensation and employee benefits . research and development employees are engaged in the design and development of power electronics , semiconductors , powerline communications and networking and software functionality . research and development expense also includes third-party design and development costs , testing and evaluation costs , depreciation expense and other indirect costs . we devote substantial resources in ongoing research and development programs that focus on enhancements to and cost efficiencies in our existing products and timely development of new products that utilize technological innovation to drive down product costs , improve functionality , and enhance reliability . we intend to continue to invest substantial resources in our research and development efforts because we believe they are critical to maintaining our competitive position . sales and marketing expense consists primarily of personnel-related expenses such as salaries , commissions , incentive compensation , stock-based compensation , employee benefits and travel . it also includes trade shows , marketing , customer support and other indirect costs . we expect to continue to make the necessary investments to enable us to execute our strategy to increase our market penetration geographically and enter into new markets by expanding our customer base of distributors , large installers , oems and strategic partners . historically , substantially all of our sales have been in the united states and canada . we began selling into france , italy and the benelux region in the fourth quarter of 2011 and commenced volume shipments to such regions in the second quarter of 2012. in addition , we opened a sales office in the united kingdom during the second quarter of 2012 and began shipping products to the united kingdom in the third quarter of 2012. in late 2013 , we expanded into the australia and new zealand markets by opening a sales office in australia . we expect to continue to expand the geographic reach of our product offerings and explore new sales channels in addressable markets in the future . general and administrative expense consists primarily of salaries , incentive compensation , stock-based compensation and employee benefits for personnel related to our executive , finance , human resources , information technology and legal organizations . general and administrative expense also includes facilities costs and fees for professional services . professional services consist primarily of outside legal , accounting and information technology consulting costs . other income ( expense ) , net other income ( expense ) , net includes interest expense on amounts outstanding under our term loans , convertible note facility and non-cash interest expense related to the amortization of debt discounts and deferred financing costs . other income ( expense ) , net also includes gains or losses upon conversion of non-u.s. dollar transactions into u.s. dollars and from foreign currency forward contracts . 31 provision for income taxes we are subject to income taxes in the countries where we sell our products . historically , we have primarily been subject to taxation in the united states because we have sold the vast majority of our products to customers in the united states . as we have expanded the sale of products to customers outside the united states , we have become subject to taxation based on the foreign statutory rates in the countries where these sales took place . as sales in foreign jurisdictions increase in the future , our effective tax rate may fluctuate accordingly . story_separator_special_tag revenues from sales of microinverters and related accessories , and communication gateways are recognized when : ( i ) persuasive evidence of an arrangement exists ; ( ii ) delivery of the products has occurred in accordance with the terms of the sales agreement and title and risk of loss have passed to the customer ; ( iii ) the sale price is fixed or determinable ; and ( iv ) collection is reasonably assured . provisions for rebates , sales incentives , and discounts to customers are accounted for as reductions in revenue in the same period the related sales are recorded . sales of an envoy communications gateway device include the enlighten web-based monitoring service . the allocation of revenue between the two deliverables is based on our best estimate of selling price determined by considering multiple factors including , internal costs , gross margin and historical pricing practices . after allocating the overall consideration from such sale to each deliverable using a best estimate of the selling price , ( i ) revenue from the sale of envoy devices is recognized upon shipment , assuming all other revenue recognition criteria have been met and ( ii ) revenue from the web-based monitoring service is recognized ratably over the estimated economic life of the related envoy devices of 10 years . inventory inventory is valued at the lower of cost or market . we determine cost on a first-in first-out basis . certain factors could affect the realizable value of its inventory , including customer demand and market conditions . management assesses the valuation on a quarterly basis and writes down the value for any excess and obsolete inventory based upon expected demand , anticipated sales price , effect of new product introductions , product obsolescence , customer concentrations , product merchantability and other factors . inventory write-downs are equal to the difference between the cost of inventories and their estimated net realizable market value . in 2014 and 2013 , write-downs of inventories were insignificant . in 2012 , we recorded write-downs of inventories of $ 0.8 million . business combinations we allocate the fair value of purchase consideration to the tangible and intangible assets acquired , and liabilities assumed based on their estimated fair values at the acquisition date . we use judgment to estimate the fair value of contingent consideration ( a component of the purchase consideration ) , identify all the tangible and intangible assets acquired , estimate the fair value of these assets , estimate the useful life of the assets , and assess the appropriate method for recognizing depreciation or amortization expense over the asset 's useful life . we believe that the accounting estimates related to purchase price allocations are critical accounting estimates because the assumptions impact the amounts and classifications of assets and liabilities presented in our consolidated balance sheets , the future amount of amortization and depreciation expense that will be recorded in our consolidated statements of operations , and the amount of goodwill which will be subject to impairment testing performed in subsequent periods . critical estimates in valuing contingent consideration include but are not limited to probabilities applied to multiple payout scenarios and a risk-adjusted discount rate . critical estimates in valuing intangible assets ( i.e . customer relationships ) include but are not limited to future expected cash flows from customer relationships and customer attrition rates . management 's estimates of fair value are based upon assumptions believed to be reasonable , but which are inherently uncertain and unpredictable and , as a result , actual results may differ from estimates . 38 warranty obligations microinverters sold through december 31 , 2013 our warranty accrual provides for the replacement of microinverter units that fail during the product 's warranty term ( 15 years for first and second generation microinverters and up to 25 years for third and fourth generation microinverters ) . on a quarterly basis , we employ a consistent , systematic and rational methodology to assess the adequacy of its warranty liability . this assessment includes updating all key estimates and assumptions for each generation of product , based on historical results , trends and the most current data available as of the filing date . the key estimates and assumptions used in the warranty liability are thoroughly reviewed by management on a quarterly basis . the key estimates used by us to estimate its warranty liability are : ( 1 ) the number of units expected to fail over time ( i.e . failure rate ) ; ( 2 ) the number of failed units expected to result in warranty claims over time ( i.e . claim rate ) ; and ( 3 ) the per unit cost of replacement units , including outbound shipping and limited labor costs , expected to be incurred to replace failed units over time ( i.e . replacement cost ) . estimated failure rates— our quality and reliability department has primary responsibility to determine the estimated failure rates for each generation of microinverter . to establish initial failure rate estimates for each generation of microinverter , our quality engineers use a combination of industry standard mtbf ( mean time between failure ) estimates for individual components contained in its microinverters , third party data collected on similar equipment deployed in outdoor environments similar to those in which our microinverters are installed , and rigorous long term reliability and accelerated life cycle testing which simulates the service life of the microinverter in a short period of time . as units are deployed into operating environments , we continue to monitor product performance via our enlighten monitoring platform . it typically takes three to nine months between the date of sale and date of end-user installation . consequently , our ability to monitor actual failures of units sold similarly lags by three to nine months . when a microinverter fails and is returned , we performs diagnostic root cause

cash flows from operating activities for 2014 , net cash provided by operating activities was $ 24.2 million . our net loss of $ 8.1 million was more than offset by non-cash charges and net changes in operating assets and liabilities . non-cash charges included $ 9.7 million of stock-based compensation , $ 8.3 million of depreciation and amortization and $ 1.4 million of other non-cash charges . in addition , cash provided by net changes in operating assets and liabilities was $ 12.8 million . sources of cash totaled $ 34.1 million resulting from an increase of $ 25.3 million in accounts payable , accrued and other liabilities , an increase of $ 5.3 million in deferred revenues and an increase of $ 3.5 million in warranty obligations . the increases in accounts payable , deferred revenues and warranty obligations were primarily attributable to higher sales volume and inventory purchases . accrued and other liabilities increased primarily due to amounts due under our annual incentive compensation plan . uses of cash included a $ 13.7 million increase in accounts receivable , a $ 5.0 million increase in inventory and a $ 2.5 million increase in prepaid expenses and other assets .


 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 from operating activities for 2014 , net cash provided by operating activities was $ 24.2 million . our net loss of $ 8.1 million was more than offset by non-cash charges and net changes in operating assets and liabilities . non-cash charges included $ 9.7 million of stock-based compensation , $ 8.3 million of depreciation and amortization and $ 1.4 million of other non-cash charges . in addition , cash provided by net changes in operating assets and liabilities was $ 12.8 million . sources of cash totaled $ 34.1 million resulting from an increase of $ 25.3 million in accounts payable , accrued and other liabilities , an increase of $ 5.3 million in deferred revenues and an increase of $ 3.5 million in warranty obligations . the increases in accounts payable , deferred revenues and warranty obligations were primarily attributable to higher sales volume and inventory purchases . accrued and other liabilities increased primarily due to amounts due under our annual incentive compensation plan . uses of cash included a $ 13.7 million increase in accounts receivable , a $ 5.0 million increase in inventory and a $ 2.5 million increase in prepaid expenses and other assets .
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 Suspicious Activity Report : our revenue growth is dependent on our ability to develop and introduce new products to meet the changing technology and performance requirements of our customers , the diversification and expansion of our revenue base , and our ability to market our products in a manner that increases awareness for microinverter technology and differentiates us in the marketplace . 30 cost of revenues and gross profit cost of revenues is comprised primarily of product costs , warranty , manufacturing personnel and logistics costs , freight costs , depreciation and amortization of test equipment and hosting services costs . our product costs are impacted by technological innovations , such as advances in semiconductor integration and new product introductions , economies of scale resulting in lower component costs , and improvements in production processes and automation . certain costs , primarily personnel and depreciation and amortization of test equipment , are not directly affected by sales volume . we outsource our manufacturing to third-party contract manufacturers and generally negotiate product pricing with them on a quarterly basis . we believe our contract manufacturing partners have sufficient production capacity to meet the growing demand for our products for the foreseeable future . however , shortages in the supply of certain key raw materials could adversely affect our ability to meet customer demand for our products . in addition , third parties , including one of our contract manufacturers , serve as our logistics providers by warehousing and delivering our products in north america , europe , australia and new zealand . gross profit may vary from quarter to quarter and is primarily affected by our average selling prices , product cost , product mix , warranty costs ( including changes in estimates ) and sales volume fluctuations resulting from seasonality . operating expenses operating expenses consist of research and development , sales and marketing and general and administrative expenses . personnel-related costs are the most significant component of each of these expense categories and include salaries , benefits , payroll taxes , recruiting costs , sales commissions , incentive compensation and stock-based compensation . we expect personnel costs to continue to increase as we hire new employees to support our anticipated growth . we expect that each of the categories of operating expenses discussed below will increase in absolute dollars , but will decline as a percentage of total revenues in the long term . research and development expense includes personnel-related expenses such as salaries , incentive compensation , stock-based compensation and employee benefits . research and development employees are engaged in the design and development of power electronics , semiconductors , powerline communications and networking and software functionality . research and development expense also includes third-party design and development costs , testing and evaluation costs , depreciation expense and other indirect costs . we devote substantial resources in ongoing research and development programs that focus on enhancements to and cost efficiencies in our existing products and timely development of new products that utilize technological innovation to drive down product costs , improve functionality , and enhance reliability . we intend to continue to invest substantial resources in our research and development efforts because we believe they are critical to maintaining our competitive position . sales and marketing expense consists primarily of personnel-related expenses such as salaries , commissions , incentive compensation , stock-based compensation , employee benefits and travel . it also includes trade shows , marketing , customer support and other indirect costs . we expect to continue to make the necessary investments to enable us to execute our strategy to increase our market penetration geographically and enter into new markets by expanding our customer base of distributors , large installers , oems and strategic partners . historically , substantially all of our sales have been in the united states and canada . we began selling into france , italy and the benelux region in the fourth quarter of 2011 and commenced volume shipments to such regions in the second quarter of 2012. in addition , we opened a sales office in the united kingdom during the second quarter of 2012 and began shipping products to the united kingdom in the third quarter of 2012. in late 2013 , we expanded into the australia and new zealand markets by opening a sales office in australia . we expect to continue to expand the geographic reach of our product offerings and explore new sales channels in addressable markets in the future . general and administrative expense consists primarily of salaries , incentive compensation , stock-based compensation and employee benefits for personnel related to our executive , finance , human resources , information technology and legal organizations . general and administrative expense also includes facilities costs and fees for professional services . professional services consist primarily of outside legal , accounting and information technology consulting costs . other income ( expense ) , net other income ( expense ) , net includes interest expense on amounts outstanding under our term loans , convertible note facility and non-cash interest expense related to the amortization of debt discounts and deferred financing costs . other income ( expense ) , net also includes gains or losses upon conversion of non-u.s. dollar transactions into u.s. dollars and from foreign currency forward contracts . 31 provision for income taxes we are subject to income taxes in the countries where we sell our products . historically , we have primarily been subject to taxation in the united states because we have sold the vast majority of our products to customers in the united states . as we have expanded the sale of products to customers outside the united states , we have become subject to taxation based on the foreign statutory rates in the countries where these sales took place . as sales in foreign jurisdictions increase in the future , our effective tax rate may fluctuate accordingly . story_separator_special_tag revenues from sales of microinverters and related accessories , and communication gateways are recognized when : ( i ) persuasive evidence of an arrangement exists ; ( ii ) delivery of the products has occurred in accordance with the terms of the sales agreement and title and risk of loss have passed to the customer ; ( iii ) the sale price is fixed or determinable ; and ( iv ) collection is reasonably assured . provisions for rebates , sales incentives , and discounts to customers are accounted for as reductions in revenue in the same period the related sales are recorded . sales of an envoy communications gateway device include the enlighten web-based monitoring service . the allocation of revenue between the two deliverables is based on our best estimate of selling price determined by considering multiple factors including , internal costs , gross margin and historical pricing practices . after allocating the overall consideration from such sale to each deliverable using a best estimate of the selling price , ( i ) revenue from the sale of envoy devices is recognized upon shipment , assuming all other revenue recognition criteria have been met and ( ii ) revenue from the web-based monitoring service is recognized ratably over the estimated economic life of the related envoy devices of 10 years . inventory inventory is valued at the lower of cost or market . we determine cost on a first-in first-out basis . certain factors could affect the realizable value of its inventory , including customer demand and market conditions . management assesses the valuation on a quarterly basis and writes down the value for any excess and obsolete inventory based upon expected demand , anticipated sales price , effect of new product introductions , product obsolescence , customer concentrations , product merchantability and other factors . inventory write-downs are equal to the difference between the cost of inventories and their estimated net realizable market value . in 2014 and 2013 , write-downs of inventories were insignificant . in 2012 , we recorded write-downs of inventories of $ 0.8 million . business combinations we allocate the fair value of purchase consideration to the tangible and intangible assets acquired , and liabilities assumed based on their estimated fair values at the acquisition date . we use judgment to estimate the fair value of contingent consideration ( a component of the purchase consideration ) , identify all the tangible and intangible assets acquired , estimate the fair value of these assets , estimate the useful life of the assets , and assess the appropriate method for recognizing depreciation or amortization expense over the asset 's useful life . we believe that the accounting estimates related to purchase price allocations are critical accounting estimates because the assumptions impact the amounts and classifications of assets and liabilities presented in our consolidated balance sheets , the future amount of amortization and depreciation expense that will be recorded in our consolidated statements of operations , and the amount of goodwill which will be subject to impairment testing performed in subsequent periods . critical estimates in valuing contingent consideration include but are not limited to probabilities applied to multiple payout scenarios and a risk-adjusted discount rate . critical estimates in valuing intangible assets ( i.e . customer relationships ) include but are not limited to future expected cash flows from customer relationships and customer attrition rates . management 's estimates of fair value are based upon assumptions believed to be reasonable , but which are inherently uncertain and unpredictable and , as a result , actual results may differ from estimates . 38 warranty obligations microinverters sold through december 31 , 2013 our warranty accrual provides for the replacement of microinverter units that fail during the product 's warranty term ( 15 years for first and second generation microinverters and up to 25 years for third and fourth generation microinverters ) . on a quarterly basis , we employ a consistent , systematic and rational methodology to assess the adequacy of its warranty liability . this assessment includes updating all key estimates and assumptions for each generation of product , based on historical results , trends and the most current data available as of the filing date . the key estimates and assumptions used in the warranty liability are thoroughly reviewed by management on a quarterly basis . the key estimates used by us to estimate its warranty liability are : ( 1 ) the number of units expected to fail over time ( i.e . failure rate ) ; ( 2 ) the number of failed units expected to result in warranty claims over time ( i.e . claim rate ) ; and ( 3 ) the per unit cost of replacement units , including outbound shipping and limited labor costs , expected to be incurred to replace failed units over time ( i.e . replacement cost ) . estimated failure rates— our quality and reliability department has primary responsibility to determine the estimated failure rates for each generation of microinverter . to establish initial failure rate estimates for each generation of microinverter , our quality engineers use a combination of industry standard mtbf ( mean time between failure ) estimates for individual components contained in its microinverters , third party data collected on similar equipment deployed in outdoor environments similar to those in which our microinverters are installed , and rigorous long term reliability and accelerated life cycle testing which simulates the service life of the microinverter in a short period of time . as units are deployed into operating environments , we continue to monitor product performance via our enlighten monitoring platform . it typically takes three to nine months between the date of sale and date of end-user installation . consequently , our ability to monitor actual failures of units sold similarly lags by three to nine months . when a microinverter fails and is returned , we performs diagnostic root cause

