On September 28 2011, the HIT Standards Committee (HITSC) will officially deliver to ONC its 6 months of hard work from Standards Summer Camp. HITSC subcommittees and workgroups have met every other day since April to prepare the standards recommendations needed to support Meaningful Use Stage 2 rule making.
The S&I Framework teams have been working in parallel on important issues - Certificates, Provider Directories, Lab Result Reporting, and Transfer of Care Summaries.
Here's how it all fits together.
Certificate Recommendations - HITSC recommended specific implementation guidance for X.509 certificates. The S&I Framework teams developed a strategy for certificate authorities to issue trusted credentials that will eventually be cross-certified with the Federal Bridge Certificate Authority (FBCA), enabling exchange with Federal agencies.
Metadata recommendations - HITSC recommended CDA R2 headers for patient, provenance, and security metadata. These were included in the Advanced Notice of Proposed Rulemaking. HIEs should use these standards as metadata envelopes for content payloads that are sent between different organizations.
Provider Directory recommendations - HITSC considered LDAP but noted that federated LDAP directories and internet-based LDAP queries between organizations have not yet been widely deployed. HITSC also considered microdata and web search engine retrieval of structured directory data. The S&I Framework teams concluded that pilots of federated LDAP queries and microdata are a reasonable next step, because no provider directory standard is mature. Additionally the S&I Framework teams recommended DNS for certificate distribution with the addition of LDAP if an organization's implementation of DNS does not support certificate discovery.
Vocabulary recommendations - HITSC recommended a parsimonious set of standards for vocabularies supporting quality measures including SNOMED-CT for problems, LOINC for labs, and RxNorm for medications. The September HITSC meeting will include a transition plan for those vocabulary standards required for Stage 1 that are being retired/replaced in Stage 2.
Patient Matching recommendations - HITSC recommended a set of best practices that will guide implementors who want to match patients using demographic data elements with appropriate specificity and sensitivity.
ePrescribing of Discharged Medications recommendations - HITSC recommended NCPDP and HL7 standards that are widely implemented and compliant with Medicare Part D requirements.
Public Health recommendations - HITSC recommended HL7 2.51 implementation guides for syndromic surveillance, reportable lab, and immunizations - one highly constrained implementation guide for each transaction.
NwHIN recommendations - At September's meeting, HITSC will recommend one set of building blocks to support Nationwide Health Information Network Exchange transactions (pull/push) and Direct transactions (push).
Lab Results recommendations - The S&I Framework teams recommended an HL7 2.51 transaction that is very similar to the public health implementation guides already approved by HITSC. It also includes vocabularies and code sets that constrain the optionality of the transaction. The Implementation Guide is broadly supported by ELINCS developers, commercial labs, and numerous informatics experts. It will be balloted by HL7 in the next few weeks and then piloted before any regulations are written.
Transitions of Care recommendations - The S&I Framework teams recommended a transfer of care summary that is a natural stepwise evolution of the work we've done for the past 10 years - CDA --> CCD --> C32 --> transfer of care CDA templates. These CDA templates are easier to implement than C32 and more flexible, Given that CCR is a declining standard (little new work is being done on it), CDA templates are a reasonable next step. The HITSC will be asked to comment on the trajectory of this work and will evaluate the results of pilot testing.
At the September meeting of the HITSC, we'll review all the work we've done as well as the S&I Framework efforts on Certificates, Provider Directories, Reportable Lab and Transfers of Care.
What evaluation criteria should we use? In the words of Doug Fridsma, who oversees the ONC Office of Standards and Interoperability
"While it might not be perfect, does it represent the best we have so far?
Does it point us in the right direction?
Is it the next step in an incremental approach to refining the standards and implementation guides?
Does it support our policy objectives?
Can we update it as needed through the SDO community?
All standards, even those that have wide-spread uptake, require constant updating and refinement. Vocabularies, terminologies, and other existing standards will require piloting to make sure that we maintain relevance.
We can't let the perfect be the enemy of good. Standards will require continued support and community refinement. If we can generally answer 'yes' to the questions above, then we need to continue to push forward toward the goals of interoperable health exchange."
I look forward to the September meeting and the delivery of all the great work done by the HITSC and S&I framework teams, bringing closure to this phase of Stage 2 preparation activities.
Wednesday, August 31, 2011
Tuesday, August 30, 2011
Lessons Learned from Steve Jobs
I recently spoke with several reporters about Steve Jobs' impact on healthcare , thanking him for the past 15 years of innovation. In preparing for those interviews, I reviewed Steve's career milestones,
In 1997, Apple Computer was in trouble. Its sales had declined from 11 billion in 1995 to 7 billion in 1997. Its energies were focused on battling Microsoft. It had lost its way.
Steve Jobs made these remarks at MacWorld 1997, a few months before becoming Apple's CEO. He outlined a simple go forward plan:
1. Board of Directors
2. Focus on Relevance
3. Invest in Core Assets
4. Meaningful Partnerships
5. New Product Paradigm
How can we apply these 5 ideas to the work we're doing in HIT?
It's clear that Health Information Exchanges across the country are in trouble - CareSpark closed its doors, the CEO of Cal eConnect resigned, and Minnesota Health Information Exchange ceased operations.
Let's consider the application of Steve's principles to Healthcare Information Exchange in Massachusetts.
1. Board of Directors - Governance in general is very important to healthcare information exchange. HIEs need a multi-stakeholder governance body to set priorities, monitor progress, and ensure all stakeholders are engaged. In the past few months, state government and the private sector experts have worked together to define roles and responsibilities. The State's HIE coordinator, Rick Shoup, and I presented this consensus plan to the state's HIT Council, the decision making body established by state regulation Chapter 305. Governance will be done by the HIT Council plus an HIT HIE Advisory Group consisting of payers, providers, employers, patients, academics, and government. This "Board of Directors" of the Massachusetts HIE activities is top notch.
2. Focus on Relevance - HIEs can do many things. They can push data among payers, providers, patients, and public health. They can create master patient indexes, record locator services, and registries. However, what will the market pay for today? At the moment, simple secure transport that connects every stakeholder with easy to use web applications and native EHR interfaces seems to be the answer. Rather than do everything simultaneously, we need to tightly focus on just secure routing, making 2012 the year of the state "information highway".
3. Invest in Core Assets - Massachusetts already has production HIEs that serve the business needs of several customers. We have NEHEN, CHAPS, SafeHealth, North Adams HIE, and the MAeHC Quality Data Center. Rather than reinvent these, we need to focus on the gaps, creating a state backbone that will connect every stakeholder, establishing a network of networks that leverages existing investments.
4. Meaningful Partnerships - The State Medicaid Health Plan includes 14 projects that cover over 90% of the providers in Massachustets. Since Medicaid is eligible for 90/10 matching funds (90% Federal/10% State), it makes great sense to do as much as we can via Medicaid. Multiplying our purchasing power by 10 is a meaningful partnership!
5. New Products - Once connectivity from every stakeholder to every stakeholder is in place, we can create novel functionality such as clinical registries and the ability to query data to support the "unconscious in the emergency department" use case.
Thus, if 2011 was the year of governance, 2012 will be the year of connectivity, 2013 the year of registries, and 2014 the year of queries.
Thanks Steve, for an approach that gives us focus and momentum. I'm completely confident our Massachustets HIE activities will succeed by embracing your 5 principles.
In 1997, Apple Computer was in trouble. Its sales had declined from 11 billion in 1995 to 7 billion in 1997. Its energies were focused on battling Microsoft. It had lost its way.
Steve Jobs made these remarks at MacWorld 1997, a few months before becoming Apple's CEO. He outlined a simple go forward plan:
1. Board of Directors
2. Focus on Relevance
3. Invest in Core Assets
4. Meaningful Partnerships
5. New Product Paradigm
How can we apply these 5 ideas to the work we're doing in HIT?
It's clear that Health Information Exchanges across the country are in trouble - CareSpark closed its doors, the CEO of Cal eConnect resigned, and Minnesota Health Information Exchange ceased operations.
Let's consider the application of Steve's principles to Healthcare Information Exchange in Massachusetts.
1. Board of Directors - Governance in general is very important to healthcare information exchange. HIEs need a multi-stakeholder governance body to set priorities, monitor progress, and ensure all stakeholders are engaged. In the past few months, state government and the private sector experts have worked together to define roles and responsibilities. The State's HIE coordinator, Rick Shoup, and I presented this consensus plan to the state's HIT Council, the decision making body established by state regulation Chapter 305. Governance will be done by the HIT Council plus an HIT HIE Advisory Group consisting of payers, providers, employers, patients, academics, and government. This "Board of Directors" of the Massachusetts HIE activities is top notch.
2. Focus on Relevance - HIEs can do many things. They can push data among payers, providers, patients, and public health. They can create master patient indexes, record locator services, and registries. However, what will the market pay for today? At the moment, simple secure transport that connects every stakeholder with easy to use web applications and native EHR interfaces seems to be the answer. Rather than do everything simultaneously, we need to tightly focus on just secure routing, making 2012 the year of the state "information highway".
3. Invest in Core Assets - Massachusetts already has production HIEs that serve the business needs of several customers. We have NEHEN, CHAPS, SafeHealth, North Adams HIE, and the MAeHC Quality Data Center. Rather than reinvent these, we need to focus on the gaps, creating a state backbone that will connect every stakeholder, establishing a network of networks that leverages existing investments.
4. Meaningful Partnerships - The State Medicaid Health Plan includes 14 projects that cover over 90% of the providers in Massachustets. Since Medicaid is eligible for 90/10 matching funds (90% Federal/10% State), it makes great sense to do as much as we can via Medicaid. Multiplying our purchasing power by 10 is a meaningful partnership!
5. New Products - Once connectivity from every stakeholder to every stakeholder is in place, we can create novel functionality such as clinical registries and the ability to query data to support the "unconscious in the emergency department" use case.
Thus, if 2011 was the year of governance, 2012 will be the year of connectivity, 2013 the year of registries, and 2014 the year of queries.
Thanks Steve, for an approach that gives us focus and momentum. I'm completely confident our Massachustets HIE activities will succeed by embracing your 5 principles.
Monday, August 29, 2011
At Home with Hurricane Irene
For the past 2 years, I've operated a weather station which provides realtime data for Wellesley, Massachusetts to the National Weather Service, the Citizens Weather Observation Program, and Weather Underground.
If you search Google for Weather Wellesley, you'll get my data.
For graphs of the temperature, barometric pressure, wind speed, wind direction, and rainfall rate during Irene, here's a summary from Weather Underground.
To prepare for the storm, I took down flags, removed hanging bird houses, and stored every object that could become a projectile in the wind.
Interestingly, we never had sustained winds more than 10 mph. Our peak gust was 17 mph. Likely, the impact of the storm on my location was much less than the surrounding neighborhood because of the grove of old hemlocks nearby that serves as a windbreak.
However, we did have a substantial amount of rain - 2.24 inches on Sunday and 4.66 inches in 24 hours related to Irene.
I retrofitted all our gutters with extenders to push water away from the house and sandbagged the bulkhead to our basement, just in case standing water accumulated in the backyard.
The key technology that saved our house was not anything wind related, but was the disaster recovery sump pump I created last year.
At the height of rain intensity, a tree down the street collapsed. due to the weight of water on its leaf canopy, and fell through power lines. The Department of Water and Power cut power to the neighborhood to do the repair.
Water began rising in my basement drains and as designed, the battery backup sump pump worked perfectly, pumping the basement dry despite the loss of power.
Installing a battery backup sump pump makes great sense - the likelihood is that in the worst storms, you'll also lose power, so having an AC powered sump pump will not help you (unless you engineer a complete alternative power solution for your home)
If my neighborhood was typical, the storm did have a profound impact. Down the street, a tree fell into two cars. My father in law lost a portion of his entry roof. Downed limbs have impacted traffic flows throughout the area.
However, our engineered systems for power backup and water control plus our preparation for the storm made our experience of Irene, our first hurricane, uneventful.
Friday, August 26, 2011
Cool Technology of the Week
I've written about strong identity management and the use of biometrics for secure applications such as prescribing controlled substances.
Bio-key, a web-based biometric provider we have used at BIDMC, has now developed an iPhone and iPad finger print reader that does identity verification in the cloud.
Although I've argued with the FDA that SMS messages sent to clinician cell phones should be enough for 2 factor authentication, their response has been that doctors cannot use Blackberry's, they must use Barackberry's - fully encrypted highly secure devices when writing e-prescriptions.
Bio-key's approach to two factor authentication on iPhones and iPads will enable a new level of functionality and productivity for clinicians who want to use these consumer platforms for healthcare applications. Today, over 1000 physicians at BIDMC use iPads and they are becoming the mobile device of choice for clinicians.
A cloud-based biometric authentication system for iPhones and iPads. That's cool!
Bio-key, a web-based biometric provider we have used at BIDMC, has now developed an iPhone and iPad finger print reader that does identity verification in the cloud.
Although I've argued with the FDA that SMS messages sent to clinician cell phones should be enough for 2 factor authentication, their response has been that doctors cannot use Blackberry's, they must use Barackberry's - fully encrypted highly secure devices when writing e-prescriptions.
Bio-key's approach to two factor authentication on iPhones and iPads will enable a new level of functionality and productivity for clinicians who want to use these consumer platforms for healthcare applications. Today, over 1000 physicians at BIDMC use iPads and they are becoming the mobile device of choice for clinicians.
A cloud-based biometric authentication system for iPhones and iPads. That's cool!
Thursday, August 25, 2011
Preparing for the College Transition
In one week, we drop off our daughter to Tufts University so she can began the next era of her life as a college woman.
All of us have been preparing.
High School is a time of many emotions - high highs and low lows. It's about discovering independence, making choices, accepting responsibility, developing relationships, and balancing parental authority with the desire for autonomy.
More is expected of today's teens than in my generation. It's very stressful on a young person.
In one week, she'll make decisions on her own. She'll decide what to eat (and drink), when to study, and who to spend her time with.
Over the past few weeks, she's thought about her transition in a very spiritual way.
I did not approach my college transition formally. I packed my clothes and typewriter the night before and we drove from Los Angeles to Stanford for the drop off. That was 31 years ago this week.
She realizes that she has to prepare for this new era while bringing closure to her childhood growing up in Wellesley, Massachusetts.
She has thought about all her Wellesley relationships. She's scheduled events with every one of her friends to create positive memories and energy before they go their separate ways. She's arranged hikes, picnics, movies, meals, and sleepovers.
She's taken private walks to her favorite places in Wellesley. She's also made a conscious decision not to visit many of the places she treasured when very young so that she can remember them as they were from a child's point of view.
Yes, she'll stay in touch with friends on Facebook, but that will fade as she develops new relationships, new interests, and new goals. The closure she's bringing now will leave lasting memories among all her friends, creating a sense of optimism and energy for the future ahead.
My wife and I know that next Wednesday will be hard. We'll bring our daughter's carefully packed belongings (4 small bins that will fit perfectly in a cozy dorm room) to her new living space, set up her IT infrastructure (the home CIO at your service), and attend a formal matriculation ceremony. My wife and I will give her the space she needs to bond with her new colleagues and we'll retreat to a quiet vegan cafe to reflect on the next era in our lives.
We've already planned a few short trips together. My wife will join me for keynote addresses in Burlington Vermont, Phoenix Arizona, and London England. We've already planned a family get together on Mt. Monadnock over Columbus Day weekend. We've thought about the next few months and years as we've considered the implications of staying close to our daughter, our parents, and our jobs.
The end result is a solid plan that will launch all of us into the next stage of life. For my daughter, it's adulthood. For my wife and I, it's a refocus on each other, the world around us, and our careers. The past 18 years with our daughter have been a gift, but the next era will be positive for all of us too. Our evolution begins next Wednesday.
All of us have been preparing.
High School is a time of many emotions - high highs and low lows. It's about discovering independence, making choices, accepting responsibility, developing relationships, and balancing parental authority with the desire for autonomy.
More is expected of today's teens than in my generation. It's very stressful on a young person.
In one week, she'll make decisions on her own. She'll decide what to eat (and drink), when to study, and who to spend her time with.
Over the past few weeks, she's thought about her transition in a very spiritual way.
I did not approach my college transition formally. I packed my clothes and typewriter the night before and we drove from Los Angeles to Stanford for the drop off. That was 31 years ago this week.
She realizes that she has to prepare for this new era while bringing closure to her childhood growing up in Wellesley, Massachusetts.
She has thought about all her Wellesley relationships. She's scheduled events with every one of her friends to create positive memories and energy before they go their separate ways. She's arranged hikes, picnics, movies, meals, and sleepovers.
She's taken private walks to her favorite places in Wellesley. She's also made a conscious decision not to visit many of the places she treasured when very young so that she can remember them as they were from a child's point of view.
Yes, she'll stay in touch with friends on Facebook, but that will fade as she develops new relationships, new interests, and new goals. The closure she's bringing now will leave lasting memories among all her friends, creating a sense of optimism and energy for the future ahead.
My wife and I know that next Wednesday will be hard. We'll bring our daughter's carefully packed belongings (4 small bins that will fit perfectly in a cozy dorm room) to her new living space, set up her IT infrastructure (the home CIO at your service), and attend a formal matriculation ceremony. My wife and I will give her the space she needs to bond with her new colleagues and we'll retreat to a quiet vegan cafe to reflect on the next era in our lives.
We've already planned a few short trips together. My wife will join me for keynote addresses in Burlington Vermont, Phoenix Arizona, and London England. We've already planned a family get together on Mt. Monadnock over Columbus Day weekend. We've thought about the next few months and years as we've considered the implications of staying close to our daughter, our parents, and our jobs.
The end result is a solid plan that will launch all of us into the next stage of life. For my daughter, it's adulthood. For my wife and I, it's a refocus on each other, the world around us, and our careers. The past 18 years with our daughter have been a gift, but the next era will be positive for all of us too. Our evolution begins next Wednesday.
Wednesday, August 24, 2011
Storage Dreams
As I continue to support the infrastructure requirements of the research faculty of Harvard Medical School (in parallel with the process to find my own successor at HMS), I have a storage dream.
The scene opens to a researcher logging into "Storage Central", a browser neutral, operating system neutral website that even runs perfectly on an iPad.
After thoughtful analysis of faculty needs, Harvard Medical School will have concluded that there are 3 different directory types in 3 different storage workflows
Directory types
a. Massive numbers of small files (i.e. next generation sequencing) that needs solid state metadata management (i.e Isilon 32000X SSD)
b. Small numbers of really large files (i.e. image processing) that needs high I/O throughput (i.e. Isilon 72000X)
c. Average numbers of average sized files that can use lower performance technologies (i.e. Isilon 72NL)
Workflows
a. Files with a high turnover rate (scratch space) that are created and destroyed daily. No snapshot or archival tier is needed
b. Files with a low turnover rate that do not need replication because the data is easy to regenerate. Snapshots are needed to protect the data against drive failure.
c. Files with a low turnover rate that need to be retained for years due to compliance requirements and the difficulty of regenerating the data. An archival tier is needed. (i.e. arrays of inexpensive 2 Terabyte drives)
The researcher sees a visual representation of her storage use in each directory and workflow, both currently and monthly over the past year. Data on primary storage, snapshots used to protect the data, and archival copies of the data are shown separately.
The researcher oversees several post docs. By clicking on a link, the researcher can see the storage use of all those she supervises.
Each directory type has a fixed three year cost per terabyte. Workflows with snapshots or archives have an incremental cost. These costs are well known and accepted by all the users.
The researcher can set their own quotas for directory types and workflows. A calculation of cost for current storage and total quota is shown. The researcher can type in a grant number or departmental account number to reserve the directory types and workflows they need.
The departmental administrator oversees many researchers. She can view the storage use of all her faculty with historical, current, and projected costs shown on screen.
She can discover who is likely to exceed their budget and who is responsible for the largest amount of storage growth over time.
An IT storage concierge is assigned to each department to help researchers and administrators move data among directory types and workflows to balance performance and cost. There is complete transparency between the demand created by the users and the supply provided by the IT department.
The Dean knows the total costs charged to departments, the IT department, and the school (as overhead components in indirect costs).
The CIO and the infrastructure team receive daily summary reports which forecast growth so that additional storage can be added as necessary, ensuring that each directory type and workflow always has 20% unused capacity. Storage vendors can ship nodes to expand each directory type and workflow within 1 week of receiving a PO, so storage can be expanded just in time without risking over or under provisioning.
The chargeback model is NIH compliant and motivates researchers to maintain files via the easy to use move/deletion tools in the web interface.
The research community, school administration, and IT are deliriously happy. Storage challenges are a solved problem. The governance committees have turned their attention to cool applications that advance science instead of infrastructure limitations that impede it.
We're assembling industry experts to work on this dream. My hope that is that I can report back in 2012 that the dream is now the Harvard Medical School reality.
Tuesday, August 23, 2011
Experience with Lion Part II
I recently wrote about my first experiences with Mac OSX Lion.
Now that I've been running Lion exclusively for a few weeks, I've learned a lot about my Macbook Air and the lifecycle of Apple products.
There are 4 variations of the Macbook air in use today:
Generation 1 - the 2008 Air with a sluggish 1.8" hard drive or an equally slow but expensive Toshiba SSD drive with 50 MB/s reads and 14MB/s writes. It had a real world battery life of 2.5 hours.
Generation 1.5 - the 2009 Air that replaced the Intel GMA X3100 integrated Graphics Processing Unit with a Nvidia GeForce 9400M to support a 1280x800 pixel display. The Toshiba SSD drive was replaced with a slightly faster Samsung 128 SSD.
Generation 2 - the 2010 Air that was SSD-only (Samsung 128C). SSD performance improved beyond that of magnetic spinning hard disk drives. A new Nvidia GeForce 320M GPU enhanced graphics performance and the Air's screen resolution was increased to 1440x900 pixels. The CPU was slower than in the previous models, but in practice it often performed better, because, unlike the old Airs, the newer ones didn't have to throttle down the CPU speed to keep the system from overheating. Generation 2 included two USB ports, but peripherals were still limited by the maximum performance of the 480Mbps USB connections. In addition, Apple introduced an 11.6" model.
Generation 3 - the 2011 Air is based on the latest Intel Sandy Bridge Core i5 and i7 CPUs, which include hardware support for AES encryption and a Graphics Processing Unit on the CPU silicon. The Mini DisplayPort connector which supported external displays in previous generations was transformed into a Thunderbolt port, which drives external displays and provides I/O at 10 Gig/s.
I purchased my Macbook Air at the end of 2009, so I have a Generation 1.5 - a 2.13 Ghz Core 2 duo with 2G of RAM and a Samsung 128 SSD.
I installed Lion and fully encrypted the filesystem with Filevault2.
In practice Generation 1.5 does not have the CPU power and I/O necessary to sustain Filevault2 and application performance for I/O intensive operations such as Mail 5.0.
Here's a study of the I/O degradation caused by Filevault2 on the Generation 2 Air - a 44% decrease. Generation 2 lacks the hardware AES encryption support (used by Filevault2) of Generation 3.
Generation 1.5 is even worse.
The end result is that Mail 5.0 on my Macbook Air could not process the typical 1500+ emails I receive each day and encrypt/decrypt the filesystem simultaneously. Deleted emails reappeared. Emails that I moved between folders unmoved. Only a reboot brought my Inbox up to date.
The solution - I reinstalled Lion without encryption and now Mail 5.0 works well, but running I/O intensive applications simultaneously like Skype 5.3 and Mail 5.0 is still problematic.
I do not store protected health information (or even personally identified information) on my laptop, so encryption is optional.
The Generation 3 Macbook Air with its I5 or I7, hardware AES support, and faster SSD drive is absolutely good enough for Lion, encryption, and I/O intensive applications. However, the Generation 1.5 is not. Running Lion and one application at a time is about all it can support.
Moore's law is alive and well at Apple, with doubling of CPU capabilities every 18 months. You should upgrade to Lion warily if you are running anything but the latest Air.
Now that I've been running Lion exclusively for a few weeks, I've learned a lot about my Macbook Air and the lifecycle of Apple products.
There are 4 variations of the Macbook air in use today:
Generation 1 - the 2008 Air with a sluggish 1.8" hard drive or an equally slow but expensive Toshiba SSD drive with 50 MB/s reads and 14MB/s writes. It had a real world battery life of 2.5 hours.
Generation 1.5 - the 2009 Air that replaced the Intel GMA X3100 integrated Graphics Processing Unit with a Nvidia GeForce 9400M to support a 1280x800 pixel display. The Toshiba SSD drive was replaced with a slightly faster Samsung 128 SSD.
Generation 2 - the 2010 Air that was SSD-only (Samsung 128C). SSD performance improved beyond that of magnetic spinning hard disk drives. A new Nvidia GeForce 320M GPU enhanced graphics performance and the Air's screen resolution was increased to 1440x900 pixels. The CPU was slower than in the previous models, but in practice it often performed better, because, unlike the old Airs, the newer ones didn't have to throttle down the CPU speed to keep the system from overheating. Generation 2 included two USB ports, but peripherals were still limited by the maximum performance of the 480Mbps USB connections. In addition, Apple introduced an 11.6" model.
Generation 3 - the 2011 Air is based on the latest Intel Sandy Bridge Core i5 and i7 CPUs, which include hardware support for AES encryption and a Graphics Processing Unit on the CPU silicon. The Mini DisplayPort connector which supported external displays in previous generations was transformed into a Thunderbolt port, which drives external displays and provides I/O at 10 Gig/s.
I purchased my Macbook Air at the end of 2009, so I have a Generation 1.5 - a 2.13 Ghz Core 2 duo with 2G of RAM and a Samsung 128 SSD.
I installed Lion and fully encrypted the filesystem with Filevault2.
In practice Generation 1.5 does not have the CPU power and I/O necessary to sustain Filevault2 and application performance for I/O intensive operations such as Mail 5.0.
Here's a study of the I/O degradation caused by Filevault2 on the Generation 2 Air - a 44% decrease. Generation 2 lacks the hardware AES encryption support (used by Filevault2) of Generation 3.
Generation 1.5 is even worse.
The end result is that Mail 5.0 on my Macbook Air could not process the typical 1500+ emails I receive each day and encrypt/decrypt the filesystem simultaneously. Deleted emails reappeared. Emails that I moved between folders unmoved. Only a reboot brought my Inbox up to date.
The solution - I reinstalled Lion without encryption and now Mail 5.0 works well, but running I/O intensive applications simultaneously like Skype 5.3 and Mail 5.0 is still problematic.
I do not store protected health information (or even personally identified information) on my laptop, so encryption is optional.
The Generation 3 Macbook Air with its I5 or I7, hardware AES support, and faster SSD drive is absolutely good enough for Lion, encryption, and I/O intensive applications. However, the Generation 1.5 is not. Running Lion and one application at a time is about all it can support.
Moore's law is alive and well at Apple, with doubling of CPU capabilities every 18 months. You should upgrade to Lion warily if you are running anything but the latest Air.
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