---
license: apache-2.0
base_model: answerdotai/ModernBERT-base
tags:
- sentence-transformers
- feature-extraction
- sentence-similarity
- biomedical
- embeddings
- life-sciences
- scientific-text
- SODA-VEC
- EMBO
datasets:
- EMBO/soda-vec-data-full_pmc_title_abstract_paired
metrics:
- cosine-similarity
---

# Negative Sampling PMB Model

## Model Description

SODA-VEC embedding model trained with negative sampling (MultipleNegativesRankingLoss). This is the PMB (PubMed) version, optimized for biomedical text similarity tasks using the standard sentence-transformers approach.

This model is part of the **SODA-VEC** (Scientific Open Domain Adaptation for Vector Embeddings) project, which focuses on creating high-quality embedding models for biomedical and life sciences text.

**Key Features:**
- Trained on **26.5M biomedical title-abstract pairs** from PubMed Central
- Based on **microsoft/BiomedNLP-BiomedBERT-base-uncased-abstract-fulltext** architecture
- Optimized for **biomedical text similarity** and **semantic search**
- Produces **768-dimensional embeddings** with mean pooling

## Training Details

### Training Data

- **Dataset**: [`EMBO/soda-vec-data-full_pmc_title_abstract_paired`](https://huggingface.co/datasets/EMBO/soda-vec-data-full_pmc_title_abstract_paired)
- **Size**: 26,473,900 training pairs
- **Source**: Complete PubMed Central baseline (July 2024)
- **Format**: Paired title-abstract examples optimized for contrastive learning

### Training Procedure

**Loss Function**: MultipleNegativesRankingLoss: standard negative sampling approach used in sentence-transformers

**Base Model**: `microsoft/BiomedNLP-BiomedBERT-base-uncased-abstract-fulltext`

**Training Configuration:**
- **GPUs**: 4
- **Batch Size per GPU**: 32
- **Gradient Accumulation**: 4
- **Effective Batch Size**: 512
- **Learning Rate**: 2e-05
- **Warmup Steps**: 100
- **Pooling Strategy**: mean
- **Epochs**: 1 (full dataset pass)

**Training Command:**
```bash
python scripts/soda-vec-train.py --config negative_sampling --push_to_hub --hub_org EMBO --save_limit 5
```

### Model Architecture

- **Base Architecture**: ModernBERT-base (12 layers, 768 hidden size)
- **Pooling**: Mean pooling over token embeddings
- **Output Dimension**: 768
- **Normalization**: L2-normalized embeddings (for VICReg-based models)

## Usage

### Using Sentence-Transformers

```python
from sentence_transformers import SentenceTransformer

# Load the model
model = SentenceTransformer("EMBO/negative_sampling_pmb")

# Encode sentences
sentences = [
    "CRISPR-Cas9 gene editing in human cells",
    "Genome editing using CRISPR technology"
]

embeddings = model.encode(sentences)
print(f"Embedding shape: {embeddings.shape}")

# Compute similarity
from sentence_transformers.util import cos_sim
similarity = cos_sim(embeddings[0], embeddings[1])
print(f"Similarity: {similarity.item():.4f}")
```

### Using Hugging Face Transformers

```python
from transformers import AutoTokenizer, AutoModel
import torch
import torch.nn.functional as F

# Load model and tokenizer
tokenizer = AutoTokenizer.from_pretrained("EMBO/negative_sampling_pmb")
model = AutoModel.from_pretrained("EMBO/negative_sampling_pmb")

# Encode sentences
sentences = [
    "CRISPR-Cas9 gene editing in human cells",
    "Genome editing using CRISPR technology"
]

inputs = tokenizer(sentences, padding=True, truncation=True, return_tensors="pt")
with torch.no_grad():
    outputs = model(**inputs)
    
# Mean pooling
embeddings = outputs.last_hidden_state.mean(dim=1)

# Normalize (for VICReg models)
embeddings = F.normalize(embeddings, p=2, dim=1)

# Compute similarity
similarity = F.cosine_similarity(embeddings[0:1], embeddings[1:2])
print(f"Similarity: {similarity.item():.4f}")
```

## Evaluation

The model has been evaluated on comprehensive biomedical benchmarks including:

- **Journal-Category Classification**: Matching journals to BioRxiv subject categories
- **Title-Abstract Similarity**: Discriminating between related and unrelated paper pairs
- **Field-Specific Separability**: Distinguishing between different biological fields
- **Semantic Search**: Retrieval quality on biomedical text corpora

For detailed evaluation results, see the [SODA-VEC benchmark notebooks](https://github.com/source-data/soda-vec).

## Intended Use

This model is designed for:

- **Biomedical Semantic Search**: Finding relevant papers, abstracts, or text passages
- **Scientific Text Similarity**: Computing similarity between biomedical texts
<!-- - **Information Retrieval**: Building search systems for scientific literature
- **Downstream Tasks**: As a base for fine-tuning on specific biomedical tasks
- **Research Applications**: Academic and research use in life sciences
 -->
## Limitations

- **Domain Specificity**: Optimized for biomedical and life sciences text; may not perform as well on general domain text
- **Language**: English only
- **Text Length**: Optimized for titles and abstracts; longer documents may require chunking
- **Bias**: Inherits biases from the training data (PubMed Central corpus)

## Citation

If you use this model, please cite:

```bibtex
@software{soda_vec,
  title = {SODA-VEC: Scientific Open Domain Adaptation for Vector Embeddings},
  author = {EMBO},
  year = {2024},
  url = {https://github.com/source-data/soda-vec}
}
```

## Model Card Contact

For questions or issues, please open an issue on the [SODA-VEC GitHub repository](https://github.com/source-data/soda-vec).

---

**Model Card Generated**: 2025-11-10