标签：#science

The mission to Phobos, Japan’s first Mars probe launch in 28 years, may reveal new information about our closest planetary neighbor.

Bluetti doesn't want you to call the Pioneer 5000 a solar generator (SoGen), even though that's what it is. What makes it slightly different from other large power stations that can be charged off solar - aka, a SoGen - is the dolly cart and up to 18KW of instant surge power available to start […]

The success of a program linking zoos across the US has created social media stars and generated a wave of interest in how to protect the endangered great apes in the wild.

With the risk of infection rising, parents and young adults are facing agonizing choices about being out in public as school starts back up.

Turning Data Into Decisions Bar charts, histograms, scatter plots, subplots, and plotting straight from pandas Previously learned to draw a line — literally. we now know how to create a figure, style it, and save it. But real analyst work rarely stops at trends over time. You'll need to compare categories , understand distributions , spot relationships between variables , and show several views of the data at once . That's exactly what today covers. Grab a coffee — let's turn raw numbers into charts that actually tell a story. 1. Bar Charts: Comparing Categories When to use one Bar charts are your go-to whenever you're comparing discrete categories against each other — regions, products, departments, months. If someone asks "which one is bigger?", a bar chart answers it instantly. The code import matplotlib.pyplot as plt regions = [ " North " , " South " , " East " , " West " ] revenue = [ 420 , 380 , 510 , 290 ] fig , ax = plt . subplots ( figsize = ( 7 , 5 )) ax . bar ( regions , revenue , color = " teal " ) ax . set_title ( " Revenue by Region " ) ax . set_xlabel ( " Region " ) ax . set_ylabel ( " Revenue ($K) " ) plt . show () A useful variant: horizontal bars When category names are long, flip the chart with barh() — it's far easier to read than squeezing labels sideways: fig , ax = plt . subplots ( figsize = ( 7 , 5 )) ax . barh ( regions , revenue , color = " darkorange " ) ax . set_title ( " Revenue by Region " ) ax . set_xlabel ( " Revenue ($K) " ) plt . show () Rule of thumb: categories on the x-axis → bar() . Long labels or many categories → barh() . 2. Histograms: Understanding Distributions Bar chart vs. histogram — don't mix them up This trips up almost every beginner: a bar chart compares separate categories. A histogram shows how continuous numeric data is distributed by grouping values into ranges called bins . There are no gaps between histogram bars by convention, because the x-axis is continuous, not categorical. The code import matplotlib.pyplot

The discovery adds to the planet’s history of strange atmospheric phenomena that scientists don’t full understand.

I've been a die-hard Computer Science fan for as long as I can remember. Right after my 10th standard, I picked up C — that was four years ago. Around the same time, GitHub pulled me in before I even understood what was happening there. I couldn't parse a single line of what people were building, but I could tell something big was going on. That curiosity eventually pulled me into web development, and from there, into almost every corner of tech over the next few years — AI included. Diploma: The Real Lessons Weren't in the Syllabus I just finished a 3-year Diploma in Computer Engineering. Looking back, the biggest lessons weren't in the coursework. They were in hallway conversations — friends and teachers talking about where technology and the market are headed, instead of the usual teenage small talk. Watching how an organization actually runs, what really happens day to day — that taught me more than most subjects did. A Habit I Used to See as a Flaw Here's a pattern about how I work: everything I start, I start from zero — and I don't always go deep. I finish with the basics, then move on. For a long time I saw that as a bad habit. Three years and almost every major technology later, I've changed my mind — it was the fastest way to find out that "a little bit of everything" isn't who I am. What I actually need is to dig into a system until I find the reason it works. Until I do, I can't let it go. Where That Instinct Pointed Me: Cybersecurity That same need to dig eventually pointed me toward something equal parts fun and dangerous — cybersecurity. I'm about three months into this path now, and I'm moving slowly. Not because it's too hard, but because I won't move to the next topic until every dot is connected. Loose ends don't let me sleep. What I've Learned So Far This is still the floor, not the ceiling, but it's real and hands-on: Web authentication attacks — 2FA bypass, broken password-reset logic, username enumeration through timing differences, account lo

Every charting tool eventually gets the same feature request: "show me other times this stock looked like this." It sounds like a lookup. It is not. The retrieval is the easy half. The hard half is that a correct implementation can still produce results that are quietly meaningless, and nothing in the code will tell you. Here is the method, and the failure modes worth knowing before you ship it. No claims about predictive power anywhere in this piece — the last section explains why that is a deliberate choice, not a hedge. The naive version, and why it fails immediately The obvious first attempt: take the last 30 days of closing prices as a query vector, slide it across history, compute Euclidean distance, return the closest matches. import numpy as np def naive_search ( history , query , k = 5 ): m = len ( query ) windows = np . lib . stride_tricks . sliding_window_view ( history , m ) dists = np . linalg . norm ( windows - query , axis = 1 ) idx = np . argsort ( dists )[: k ] return idx , dists [ idx ] Run this and you get garbage — but instructively specific garbage. Every match comes from whatever period had a similar price level . Query a stock trading at $180 and you get back the other times it traded near $180. The shape is irrelevant to the metric; the offset dominates it. Scale is the same problem in a different coat. A stock that moved 2% over the window and one that moved 40% can trace an identical shape, and raw distance calls them unrelated. Normalize per window, not globally The fix is to z-normalize each window independently: def znorm ( x , axis =- 1 , eps = 1e-8 ): mu = x . mean ( axis = axis , keepdims = True ) sd = x . std ( axis = axis , keepdims = True ) return ( x - mu ) / ( sd + eps ) Per-window is the load-bearing part. Normalizing the whole series once preserves the relative offsets you were trying to remove. Each candidate window has to be centered and scaled on its own terms before it's compared. There's a satisfying identity waiting here.

Have you ever wondered how your smartwatch actually knows you're stressed? Most of us treat the "Stress Score" on our wrists as a source of truth, but the logic remains hidden behind proprietary algorithms. Today, we are pulling back the curtain. We are going beyond basic heart rate tracking to perform PPG signal processing and HRV frequency domain analysis using Python. By the end of this guide, you’ll know how to ingest raw data via Bluetooth Low Energy (BLE) , apply digital filters with SciPy , and calculate the elusive LF/HF ratio to determine autonomic nervous system balance. If you are interested in advanced biometric algorithms or Python signal analysis , you’re in the right place. 🚀 The Architecture: From Photons to Stress Metrics Unlike standard heart rate (BPM), which just counts peaks, Stress Scores rely on Heart Rate Variability (HRV) —the millisecond-level variations between heartbeats. We'll be moving from raw light intensity data to a frequency-based stress index. graph TD A[Wearable Sensor / PPG] -->|Raw BLE Stream| B[Data Acquisition - Bleak] B --> C[Preprocessing - Bandpass Filter] C --> D[Peak Detection - Find R-R Intervals] D --> E[Cubic Spline Interpolation] E --> F[Fast Fourier Transform - FFT] F --> G[LF/HF Ratio Calculation] G --> H[Final Stress Score] 🛠 Prerequisites To follow this advanced tutorial, you’ll need: Hardware : A pulse oximeter or wearable that exposes raw PPG via BLE (e.g., Polar OH1, MAX30102 with an ESP32). Stack : NumPy & SciPy : For heavy-duty math and signal processing. Bleak : For cross-platform Bluetooth Low Energy communication. Matplotlib : To visualize the pulse waves. Step 1: Capturing the Raw PPG Stream (BLE) Photoplethysmography (PPG) works by shining green or red light into the skin and measuring the light absorption. First, let's grab that raw stream. import asyncio from bleak import BleakClient # UUID for the Raw PPG Characteristic (Device specific) PPG_CHAR_UUID = " 00002a37-0000-1000-8000-00805f9b34fb " def no

Gene-edited pig kidneys could offer a lifeline to patients stuck waiting for a human donor.

Stryker says its SportSuite Vision software for the headset received De Novo authorization from the FDA in July.

Insect-inspired "sparse coding" does fast learning, avoids catastrophic forgetting.

Google is rolling out an updated AI weather model that's supposed to be more accurate, especially when it comes to predicting rain and snowfall. In the announcement today, the company says it's now able to make forecasts with "unprecedented resolution" using its new WeatherNext 3 AI model. It can produce a global picture that's five […]

Every backtest has to answer a boring question: when the strategy says "buy," what price does it actually get? Most backtesting frameworks answer this question badly by default, and the badness is almost always in the strategy's favor. Here are the four assumptions that do the most damage, roughly in order of how often they show up. Mid-price fills If your backtest fills orders at the midpoint of the bid-ask spread, you are assuming you trade for free. You don't. A market order pays at least half the spread to cross it; a marketable limit order pays something close to that too, once you're honest about how often it actually gets hit versus sitting unfilled while the market moves away. Mid-price fills are the single most common way a backtest manufactures edge that doesn't exist, because the effect compounds with trade frequency — a strategy that trades often looks great on mid-price fills and mediocre-to-negative once it pays the spread on every round trip. Zero slippage Slippage is the gap between the price your signal fired at and the price your order actually executed at, and it's not just a queuing artifact — it's partly information. If your strategy is buying because something changed, other participants are reacting to the same thing, and the price you wanted is often gone by the time your order reaches the book. A backtest with zero slippage is quietly assuming the market waits for you. Unlimited size at the touch Backtests routinely assume you can execute your full position size at the best bid or ask, no matter how large the order is relative to the visible size there. In practice, a large order walks the book, and the average fill price is worse than the touch price by an amount that depends on how thin the book is. This one is invisible until you try to size up, which is exactly when a strategy that looked fine in testing starts bleeding. Commissions omitted or averaged Commissions and fees are usually small per trade and therefore easy to skip or fold in

An underground detector recorded a strange interaction pointing to a particle with some properties that signify dark matter. The detection is small but promising.

Common sense is of no help in studying reality at the atomic scale.

While companies promise they can help users monitor gut health, experts suggest that smart toilets provide little in the way of benefits to the average person.

Anker's SleepLab speaker promises to track and enhance sleep without a wearable. It uses millimeter-wave radar (60GHz) blasting from your nightstand to track micro-movements in your chest and body to continuously monitor your heart rate and breathing to enhance whatever sleep stage you're in. It also embeds lots of hippie shit. If I'm understanding things […]

The World Meteorological Organization is warning that the climate phenomenon that has the Pacific running a fever will last until at least February, with dire consequences for weather worldwide.

Is a blank cell signal, or just missing? Sometimes an empty cell is the most informative thing in the row. The trouble is that you usually only know which case you're in by reading the data dictionary — and that doesn't scale to 800 columns named f_0347 . So we measure it instead, then check the answer against the literature. Ames housing · 1,460 sales · 79 columns · 19 of them contain blanks "Drop any column that's more than 70% missing." I've written that line into more pipelines than I can count. On Ames it deletes four columns — and three of them have real price signal sitting in the gap. The blanks in this dataset are structural . A blank GarageQual doesn't mean the value was lost; it means the house has no garage. A blank Alley means no alley access. The emptiness is the measurement. That's easy to see here because the columns have English names and a published data dictionary. It is not easy to see on a vendor feed of anonymised features, which is what most real projects look like. So the question worth answering isn't "does missingness carry signal" — it's can you tell, without knowing what the column means? 0.41 R² from the blank/not-blank pattern alone — every value discarded 1.00 AUC recovering the garage blanks from other columns' values ±0.9% Total spread across five strategies — inside a ±1.5% CV noise band 1 · A blank cell has a price tag Start with the crude check: does sale price differ between rows where a column is blank and rows where it isn't? Columns that go blank on the same rows describe one fact, so the five garage columns collapse into one. Fig 1. Median sale price, blank rows vs. valued rows. No garage is a $68k median discount on a $163k median house. Note the sign flip: houses that have an alley or fence are the cheaper ones — those features mark older, denser blocks. "Blank = worse" is not a rule you can assume. Then the harder test. Throw away every value in the table and keep only a 19-column matrix of True / False — was this cell emp