#Clustering

[phoenixyfriend]

Ko-fi prompt from royaltrashpanda:

Saw your answer about why car dealerships tend to be in the same geographic area of a city. In my childhood neighborhood, we had a street with like ten used car lots all in a row on five blocks, and I’ve always wondered how that worked. They were much smaller than a standard dealership, and not all of them had repair shops attached. (Unfortunately that area has majorly gentrified and there’s none left on the original five blocks.) Based on your dealership research, what would be your take on tiny used car lots all being on the same five blocks? Also kind of related but not really, have you run into anything in your research about the history of the giant statues of men in suits that used car lots tend to have? If you have, I’d very much like to commission another question later about that topic because I’m so curious and have had no luck researching it myself!

My guess would be that they have a higher profit margin since they can probably leverage purchasing in their favor when buying those secondhand cars (especially from things like police auctions), and they can have a fairly consistent and predictable level of demand (there's almost always a new crop of teenagers getting licenses, without the cash for a brand new model), while the clustering strategy probably works even better when your business model appeals directly to a secondhand market where you might have a wide variety within one lot.

But let's see what the research says.

According to website CarEdge, some secondhand dealerships can have average profit margins as in excess of $4k. Now, that's probably skewed by some secondhand cars being luxury vehicles; there's a reason Carvana is topping that list, and most people do seem Carvana's prices on newer, low-mileage models are actually too high. The others are more like 1.5-2k profit margins, which is still respectable.

Granted, these are large dealership groups, rather than small, privately-owned businesses. Independent used car dealerships are looking at a gross profit margin of something like 10-20% depending on how well people bargain with the dealer, according to website ProfitableVenture. After the costs of owning and running the dealership (wages, mortgage, insurance, taxes, etc), there is about 2-3% left for the owner.

I actually want to quote this paragraph from them, as I feel like it's pretty informative on the issue:

The average amount of money that a car dealer makes per used car today is around $500 to $3,000 per car, with your typical run-of-the-mill used cars selling for about $2,500 to $5,000. Have in mind that profit margins on used cars are narrower than they have been in the past due to more information is available. Keeping profit margins a secret is what allows dealerships to take advantage of customers.

Now, that explains how they stay afloat, but the clustering?

...it really does come down to the same reasons as the regular car dealerships, but with the lens of anticipated costs. If you are a parent helping your teenager buy a used car, because they want your opinion and you're better at haggling than they are, then you want to make sure they get both the best possible deal, and the best/safest car possible... but also, you have work in the morning, and do not want to drive twenty minutes to each used car lot. You want to either be able to look up all the options on the internet, or hop from one lot to the next in the span of two minutes. Even with the internet, you want to do a test drive, no?

You also said that none of those dealerships exist anymore, which means they also predate the internet option. Being small means they had to sell fewer cars to stay open, but also that they didn't have the luxury of being a wide enough selection for people to do a cost-benefit analysis of coming to visit them with the expectation of finding a car when they might be able to see more options at that dealership that's only a block away from the other one. Without the internet, especially, their advertising would be limited to car commercials and newspaper ads.

(My thoughts go to Big Bill Hell's Cars and that Tobey Maguire Spidey scene where the used car from the newspaper is doing powerpoint transitions across the screen.)

So the clustering tactic is even more important, in that case. The only way to get your products in front of eyeballs is traditional media and in person, and it's a lot easier to make 'in person' happen if they're already headed to the neighbor.

[prettyvintagehouse]

[qcs01]

Optimizing Performance on Enterprise Linux Systems: Tips and Tricks

Introduction: In the dynamic world of enterprise computing, the performance of Linux systems plays a crucial role in ensuring efficiency, scalability, and reliability. Whether you're managing a data center, cloud infrastructure, or edge computing environment, optimizing performance is a continuous pursuit. In this article, we'll delve into various tips and tricks to enhance the performance of enterprise Linux systems, covering everything from kernel tuning to application-level optimizations.

Kernel Tuning:

Adjusting kernel parameters: Fine-tuning parameters such as TCP/IP stack settings, file system parameters, and memory management can significantly impact performance. Tools like sysctl provide a convenient interface to modify these parameters.

Utilizing kernel patches: Keeping abreast of the latest kernel patches and updates can address performance bottlenecks and security vulnerabilities. Techniques like kernel live patching ensure minimal downtime during patch application.

File System Optimization:

Choosing the right file system: Depending on the workload characteristics, selecting an appropriate file system like ext4, XFS, or Btrfs can optimize I/O performance, scalability, and data integrity.

File system tuning: Tweaking parameters such as block size, journaling options, and inode settings can improve file system performance for specific use cases.

Disk and Storage Optimization:

Utilizing solid-state drives (SSDs): SSDs offer significantly faster read/write speeds compared to traditional HDDs, making them ideal for I/O-intensive workloads.

Implementing RAID configurations: RAID arrays improve data redundancy, fault tolerance, and disk I/O performance. Choosing the right RAID level based on performance and redundancy requirements is crucial.

Leveraging storage technologies: Technologies like LVM (Logical Volume Manager) and software-defined storage solutions provide flexibility and performance optimization capabilities.

Memory Management:

Optimizing memory allocation: Adjusting parameters related to memory allocation and usage, such as swappiness and transparent huge pages, can enhance system performance and resource utilization.

Monitoring memory usage: Utilizing tools like sar, vmstat, and top to monitor memory usage trends and identify memory-related bottlenecks.

CPU Optimization:

CPU affinity and scheduling: Assigning specific CPU cores to critical processes or applications can minimize contention and improve performance. Tools like taskset and numactl facilitate CPU affinity configuration.

Utilizing CPU governor profiles: Choosing the appropriate CPU governor profile based on workload characteristics can optimize CPU frequency scaling and power consumption.

Application-Level Optimization:

Performance profiling and benchmarking: Utilizing tools like perf, strace, and sysstat for performance profiling and benchmarking can identify performance bottlenecks and optimize application code.

Compiler optimizations: Leveraging compiler optimization flags and techniques to enhance code performance and efficiency.

Conclusion: Optimizing performance on enterprise Linux systems is a multifaceted endeavor that requires a combination of kernel tuning, file system optimization, storage configuration, memory management, CPU optimization, and application-level optimizations. By implementing the tips and tricks outlined in this article, organizations can maximize the performance, scalability, and reliability of their Linux infrastructure, ultimately delivering better user experiences and driving business success.

For further details click www.qcsdclabs.com

[dnagenealogy]

Can a 6 cM connection be meaningful?

When it comes to small DNA segments, we’ve heard the “glass half empty” version of the story many times. Here’s the other side of that story.

Submitted for your consideration: A pair of third cousins twice removed and their 6 cM connection…

According to AncestryDNA, Bryan Smith and his cousin, K, share 6 cM of DNA across 1 segment. And according to Ancestry’s ThruLines, Bryan and Cousin K share a pair of third great grandparents, Reuben Willis Smith and his wife Mary Connell.

The cM value is certainly consistent with the identified relationship but did Bryan and Cousin K inherit their shared DNA from the Smith ancestry as shown? Is the 6 cM segment even valid or could it be an artifact of an imperfect DNA matching algorithm?

Let’s start with an easy evaluation: the shared match list.

Among Bryan and K’s list of shared matches at AncestryDNA:

HG, a descendant of Reuben and Mary’s son, Charles Thomas Smith (HG shares 57 cM with Bryan)

RR, a descendant of Reuben and Mary’s daughter, Fannie Janes Smith (RR shares 47 cM with Bryan and 38 cM with K)

IG, another descendant of Reuben and Mary’s son, Charles Thomas Smith (IG shares 47 cM with Bryan and 71 cM with K)

And at least three other descendants of Reuben and Mary are on the shared match list.

So we’re off to a promising start. In addition to the fact that Bryan and K share DNA and a paper trail leading to Ruben and Mary, this group of matches gives us more evidence suggesting that Bryan and K might be related as suspected.

But what about that 6 cM segment shared by Bryan and K? Is it valid? Did it come from the shared Smith ancestors or did it originate elsewhere?

To get the most comprehensive help in answering these questions, we turn to GEDmatch. As indicated in the ThruLine image above, both Bryan and his father are related to DNA Cousin K through their Smith line. And because K is on GEDmatch, we can see that Bryan and his father both share DNA with K on a specific portion of Chromosome 12:

Further investigation reveals that two other descendants of Reuben and Mary, Cousins I and G, share DNA with Bryan and his father on Chromosome 12 in roughly the same location. In fact, all of the matches in question match each other on Chromosome 12:

This is what we call a Triangulation Group. It brings the possible genetic connections into sharper focus.

The common segment shared by all of the members of this Triangulation Group indicates that they all share a common ancestor. And we’ve already identified shared ancestry through the Smith line. Cousins I and G are first cousins once removed and they are descendants of Reuben and Mary’s son Charles Thomas Smith...

A review of the pedigrees of the matches in question reveals no lines of shared ancestry other than the known shared Smith line. This investigation is summarized briefly in the table below, listing 2nd great grandparent surnames and shared ancestors (blue for paternal names and surnames, light red for maternal names and surnames):

Although we cannot say with perfect certainty that there is no additional common ancestry that conceivably could account for the shared segment of DNA on Chromosome 12, the known evidence doesn’t leave room for much doubt.

For completeness, here’s a chart summarizing the amount of DNA shared by the relatives in question:

And cluster analysis for Cousin G yields a cluster with eight descendants of Reuben Willis Smith, including Bryan Smith and Cousin K:

Not everyone will feel the need to go this far to investigate a 6 cM connection. But this post provides examples of ways to investigate the validity of an ordinary small segment and to determine whether the shared DNA legitimately belongs with the presumed paper trail source of the DNA.

Discussion

Skepticism regarding small segments of shared DNA is appropriate. In comparison to larger shared segments, such segments are more likely to be IBS (false).  Additionally, even when small segments can be shown to be reliable, we have to grapple with the fact that small segments can be too old to fall within the reach of reliable historical documentation. 

With the exponential growth of the DNA matching databases, the impetus to explore distant matches waned. Reluctance to do the strenuous work involved in using small segments grew. With access to strong genetic connections leading back to target ancestors, why bother with low cM connections?

The sentiment is understandable!

On the other hand, I believe that excessive skepticism has impeded progress in genetic genealogy.  As databases have grown, our opportunities for research have multiplied and our research techniques have improved. But at the same time, goalposts for small segment success have been moved to poorly-defined and very unreasonable points. 

[From the skeptics: Your success with a small segment doesn’t count if you find a larger segment in a relative! I don’t want to hear about triangulation! Visual phasing is not allowed!]

If we applied such arbitrary restrictions to all areas of genealogy, we’d struggle to get our work done!

Even with our luxuriously large DNA databases, distant genetic connections are the only connections available in some areas of investigation (or to people who hail from less heavily-tested populations). Defeatist refusal to accept low cM matches as evidence in genetic genealogy needlessly limits our potential. 

Don’t get me wrong, I’m fully in favor of scholarly rigor. But let’s not allow skepticism to pave the way for denialism! 

When distant genetic connections are found to be of dubious quality, they should be set aside. But shared segments should not be judged on the basis of size alone. Even the most fervent opponents of small-segment research will admit that small segments are often valid (IBD). And while these opponents frequently cite IBD/IBS percentages, they ironically fail to see that our ability to find these percentages points directly to a practical method for sorting distant matches on an individual basis. 

We are privileged to have access to enormous databases of incredibly valuable genetic information. More than a statistical hiccup that can lead us serendipitously to more reliable information, small DNA segments are  messages we carry with us every day, testifying to our connections with our ancestors. Genetic information, even in small amounts, can be just as valuable as any other form of information. We should be good stewards of that information and we should invest good faith effort in understanding how our distant matches can inform us about our rich ancestral history. 

I’ll close with this analogy for small segments: 

You want some refreshing water but the glass is only half-full. Drink it or toss it out?

Posted with Bryan Smith’s permission. 17 May 2023

[i-3at-s0ap]

Elon Musk isn't a sociopath Trump isn't a narcissist Jeff Bezos isn't a psycho they are terrible racist bigoted assholes but I'm begging y'all to fucking give a shit about people with personality disorders. PLEASE.

[webtodayteche]

[totoshappylife]

Wasserstein-based Kernels for Clustering: Application to

Excerpt from PDF: Wasserstein-based Kernels for Clustering: Application to Power Distribution Graphs Alfredo Onetoa, Blazhe Gjorgieva, Giovanni Sansavinia,∗ aReliability and Risk Engineering Lab, Institute of Energy and Process Engineering, Department of Mechanical and Process Engineering, ETH Zurich, Switzerland Abstract Many data clustering applications must handle objects that cannot be…

[faulknerluvr]

[autopsyfreak]

more products of my chronic boredom.

edit: since so many of you are completely misconstruing the purpose of this meme, the reason why HPD isn’t mentioned on this post is because this is specifically talking about the personality disorders that i have been diagnosed with and the demonisation i’ve experienced.

[carnage-cathedral]

btw guys managing your symptoms also means apologizing for things you didn't mean to do. sometimes you do things because of your disorders that you genuinely didn't mean to do, but if it hurt someone you still have to take accountability and make up for the hurt you caused

[happyherringbonkpickle]

[chronicsymptomsyndrome]

*displays textbook symptomatic behavior of my own disorder that I am well educated on* what’s my deal why am I like this

[fuerst-von-plan1]

Effiziente KI-Methoden zur Betrugserkennung in Versicherungen

In der heutigen schnelllebigen Welt des Versicherungsmarktes ist die Betrugserkennung eine zunehmend kritische Aufgabe. Betrugsversuche nehmen in Komplexität und Häufigkeit zu, was Versicherungsunternehmen vor erhebliche Herausforderungen stellt. Die Integration effizienter künstlicher Intelligenz (KI) Techniken hat sich als Schlüssel zur Verbesserung der Betrugsüberwachung und -bekämpfung…

[ohara-n-brown]

As a late diagnosed autist I will say one of the most damaging but transformative experiences I've ever had was being misdiagnosed with BPD.

Everyday my heart goes out to people with BPD.

The amount of stigma and silencing they face is astonishing and sickening.

I took DBT for years. Therapists use to turn me away because of my diagnosis.

I would be having full blown autistic meltdowns, crying for help literally - but because I was labeled as BPD ANY time I cried I was treated as manipulative and unstable.

As if the only reason I could be crying was if I was out to trick someone.

95% of the books out there with Borderline in the title are named shit like 'How to get away from a person with Borderline', 'How to stop walking on eggshells (with a person who has BPD)'

I was never allowed to feel true pain or panic or need.

That was 'attention seeking behavior', not me asking for help when a disability was literally inhibiting my ability to process emotions.

There were dozens of times where I had a full meltdown and was either threatened with institutionalization or told I was doing it for attention.

My failing relationships weren't due to a communication issue, or the inability to read social cues. No, because I was labeled borderline, my unstable relationships were my fault. Me beggong nuerotypicals to just be honest and blunt with what they meant was me pestering them for validation.

Borderline patients can't win.

And the funny thing is - I asked my therapist about autism. I told her I thought I was on the spectrum.

BPD is WILDLY misdiagnosed with those with autism and I had many clear signs.

Instead - she told me 'If you were autistic we wouldn't be able to have this conversation'. She made me go through a list of autistic traits made clearly for children, citing how I didn't fit each one.

And then she told me that me identifying with the autism community was the BPD making me search for identity to be accepted - and that I wasn't autistic, just desperate to fit in somewhere.

I didn't get diagnosed for another ten years. For ten years I avoided the autism community - feeling as if I were just a broken person who wanted to steal from people who 'really needed it'.

Because of my providers - I began to doubt my identity MORE, not less.

Ten years of thinking I was borderline and being emotionally neglected and demonized by a system meant to help me.

To this day, I still don't trust neurotypicals. Not fully.

I know I'm not borderline now - but my heart aches for them. Not for the usual stuff. But for the stigma. And the asshole doctors. And the dismissiveness and threatening and the idea of institutionalization hanging over their head.

I love Borderline people. I always will. I'm not Borderline but if you are I love you and I'm sorry.

You're not a bad person. You're not a therapists worst nightmare, you are a human with valid feelings and fears.

Borderline people I'm sorry.

[nofuckingideawho]

I have this silly little feeling in my chest that's making me want to die